Re: [EVDL] EV Demand Response - (solar-thermal-NOT-2)
I've had solar hot water and I currently have solar pool heating and solar PV. Solar hot water wasn't good in winter. Sure, modern systems are better at that but you end up needing to boost it with instant or storage heating in winter. Solar for your pool is great because you want it when the sun shines. Mine adds a month of extra usable pool time to each end of the season. Occasionally I use the spa heater to heat the pool but that's a $50 hit every day I do it vs a few dollars a day for the pump for the solar. John Lindsay On 18 Jan 2015, at 2:16 pm, Michael Ross via EV ev@lists.evdl.org wrote: Pool heating does indeed work - because the system does not have to meet the same requirements. It is not a sanitary system and there is no need to protect from backfeeding the potable water supply of the municipality. The equipment - all of it, is significantly less expensive. The customers are generally more well to do - they can afford a swimming pool, and so on. The payback comes more quickly and the customer may not even care about it. ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT-2)
there is 1 place at least solar thermal wins. Heating swimming pools! I accidentally got my 19,000+ gallon pool up to 99 degrees F last labor day using only rooftop solarotherwise, i agree about PV, having PV since 1999 From: Robert Bruninga via EV ev@lists.evdl.org To: ev@lists.evdl.org Sent: Wednesday, January 14, 2015 1:34 PM Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT-2) My point was that if the energy source is FREE, people don't care how much it takes or what its efficiency is. They'll use whatever is cheapest; not the most efficient. Well, we completely disagree. We are talking about rooftop solar. The system to use that solar energy is NOT free. It costs, and it costs big. And only someone with tightly held obsolete beliefs would cling to outdated inefficient conversion of that solar energy only to heat. Solar Thermal is really, really dead for the average homeowner. You were correct 10 years ago, but by 2006 PV broke even with solar water heating and now PV wins hands down. Remember, in the last decade PV solar has come down in cost 10-to-1. How much usable energy you get out of the roof divided by how much solar energy falls on that roof is a definition of EFFICIENCY. Most single-family homes probably *do* have enough roof area to provide all their energy needs. Simply *not* true in most places! You are talking about all. When you consider that all of our energy needs includes ELECTRICITY, HEATING, COOLING, and EV CHARGING, then there are VERY FEW average homes in America that can meet all of their energy needs only on their roof. Period. Go start covering your availalable roof with in-efficinent expensive thermal system, and STOP BURNING ANY OTHER FOSSIL FUEL for HEAT or DRIVING cars, and see how quickly you run out of space. You'll want PV if you do the numbers right on a year-round basis. Solar THERMAL costs more, is harder to install, requires more maintenance and delivers less (on an annual basis) in every way than the same area of today's PV (and heatpump technology). Do the math. Bob, Wb4APR -Original Message- From: Lee Hart [mailto:leeah...@earthlink.net] Sent: Wednesday, January 14, 2015 10:15 AM To: Robert Bruninga Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT) Lee Hart wrote: I think the word you want is return on investment; not efficiency. Robert Bruninga wrote: Nope. Most people only have so much roof available for solar energy. And it is not enough for our total energy needs. So it is very important how much of that surface area you turn into retail value energy and is very much an efficiency determination. You are still using efficiency in place of other figures of merit. Here, you're talking about economics; not efficiency. What does it COST, versus how much money can I GET for it. That's return on investment. Most single-family homes probably *do* have enough roof area to provide all their energy needs, regardless of the PV cell's efficiency. Efficiency measures how much energy you get out divided by how much energy YOU put in. Yes, how much do you get out VERSUS how much the SUN puts in. My point was that if the energy source is FREE, people don't care how much it takes or what its efficiency is. They'll use whatever is cheapest; not the most efficient. They decide based on economics; not efficiency. Solar thermal makes sense if you want heat. It's really GOOD at making heat! Which I don't need 7 months of the year. But I do! I live in Minnesota, where we spend more on heat than we do on electricity. Do not assume that what is best for you is best for everybody. There is a place for both PV to make electricity, and solar thermal to make heat. -- Ingenuity gets you through times of no money better than money will get you through times of no ingenuity. -- Terry Pratchett -- Lee Hart, 814 8th Ave N, Sartell MN 56377, leeah...@earthlink.net ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) -- next part -- An HTML attachment was scrubbed... URL: http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150117/5a4bf6b7/attachment.htm ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT-2)
there is 1 place at least solar thermal wins. Heating swimming pools! But all that rooftop thermal energy is doing nothing during fall, winter and spring? Does it help power the EV? It might be interesting to do some numbers. Im curious... You may be right. Pool thermal heat simply needs a lot of pipe on the roof and are pretty low cost.. But could we make these assumptions... Lets assume 19,000 gallons X 7 lbs/gal X 20 degrees = 2,660,000 BTu divided by 3400 Btu per kWh and we get about 780 kWh needed to heat that water over about 3 months?. (doing not much the other 9 months, nor doing much once the water is already hot). Now, a modest 600 watt solar PV array (just three panels) can also produce about 780 kWh per year. And cost about $600 (DIY) or about $2000 contractor installed. So how does the cost of the pool heater compare? How does the roof area of the thermal pipes compare to the 50 sqft of the PV? If PV and a heatpump water heater were used, you could heat the pool to that same amount with a SINGLE 18 sqft solar panel. How does that compare? Add another $1500 to the cost for the heatpump. The point is that the same roof area as the pool heater when used instead for PV, would not only heat the pool, but also power the EV's and power some of the house too (maybe). Im curious...? Thanks BOb, WB4APR On Sat, Jan 17, 2015 at 10:37 AM, robert winfield winfield...@yahoo.com wrote: there is 1 place at least solar thermal wins. Heating swimming pools! I accidentally got my 19,000+ gallon pool up to 99 degrees F last labor day using only rooftop solar otherwise, i agree about PV, having PV since 1999 -- *From:* Robert Bruninga via EV ev@lists.evdl.org *To:* ev@lists.evdl.org *Sent:* Wednesday, January 14, 2015 1:34 PM *Subject:* Re: [EVDL] EV Demand Response - (solar-thermal-NOT-2) My point was that if the energy source is FREE, people don't care how much it takes or what its efficiency is. They'll use whatever is cheapest; not the most efficient. Well, we completely disagree. We are talking about rooftop solar. The system to use that solar energy is NOT free. It costs, and it costs big. And only someone with tightly held obsolete beliefs would cling to outdated inefficient conversion of that solar energy only to heat. Solar Thermal is really, really dead for the average homeowner. You were correct 10 years ago, but by 2006 PV broke even with solar water heating and now PV wins hands down. Remember, in the last decade PV solar has come down in cost 10-to-1. How much usable energy you get out of the roof divided by how much solar energy falls on that roof is a definition of EFFICIENCY. Most single-family homes probably *do* have enough roof area to provide all their energy needs. Simply *not* true in most places! You are talking about all. When you consider that all of our energy needs includes ELECTRICITY, HEATING, COOLING, and EV CHARGING, then there are VERY FEW average homes in America that can meet all of their energy needs only on their roof. Period. Go start covering your availalable roof with in-efficinent expensive thermal system, and STOP BURNING ANY OTHER FOSSIL FUEL for HEAT or DRIVING cars, and see how quickly you run out of space. You'll want PV if you do the numbers right on a year-round basis. Solar THERMAL costs more, is harder to install, requires more maintenance and delivers less (on an annual basis) in every way than the same area of today's PV (and heatpump technology). Do the math. Bob, Wb4APR -Original Message- From: Lee Hart [mailto:leeah...@earthlink.net] Sent: Wednesday, January 14, 2015 10:15 AM To: Robert Bruninga Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT) Lee Hart wrote: I think the word you want is return on investment; not efficiency. Robert Bruninga wrote: Nope. Most people only have so much roof available for solar energy. And it is not enough for our total energy needs. So it is very important how much of that surface area you turn into retail value energy and is very much an efficiency determination. You are still using efficiency in place of other figures of merit. Here, you're talking about economics; not efficiency. What does it COST, versus how much money can I GET for it. That's return on investment. Most single-family homes probably *do* have enough roof area to provide all their energy needs, regardless of the PV cell's efficiency. Efficiency measures how much energy you get out divided by how much energy YOU put in. Yes, how much do you get out VERSUS how much the SUN puts in. My point was that if the energy source is FREE, people don't care how much it takes or what its efficiency is. They'll use whatever is cheapest; not the most efficient. They decide based on economics; not efficiency. Solar thermal makes sense if you want heat. It's really GOOD at making heat
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
... I question the value of a heat pump H/W heater in winter. If it's taking heat from your garage or basement, that is ultimately taking some heat from your heated spaces... Yes, one has to think about where it is. But my garage is not heated, nor is my basement. Therefore it is taking the heat from the environment which is taking it from outside (if it is your unheated garatge or fromteh ground if it is my basement. The temperature in my below ground basement never gets below 55F even during the winter no matter how much heat I pump out of it into the water heater. Nor the 10,000 BTu of heat I pump out of it via an old A/C unit serving as a heat pump by placing its cool side in the basement and its warm side into the follor of the room above. The surface area of the basement is about 2000 sqft includgint eh walls and crawlspace area. That is a huge source of latent heat, even in the winter. So I call them modest ground source heatpump systems since that is where the heat is actually coming from when I draw it from the basement. But I agree. If you put the heat pump water heater in a closet or in a heated portion of the house, one really needs to think it through.In the summer, it is great almost anywherer you put it, but if it is in a conditioned space, it should probably be exhaust vented outdoors in the winter. Bob, WB4APR which means you're simply using more energy elsewhere. If you could somehow duct the air intake from outside during winter, then it would be doing the best job it could. In summer, no doubt a true benefit. Before you argue that I'm wroing, consider this. If the air outside your garage is colder than inside and the H/W tank is cooling the garage air in exchange for heating the water, either the garage temp will drop to less than the outside or warm air will be drawn from the home's heated spaces. If you are truly insulated, then the former will happen and you will have the equivalent of ducting intake from outside. I doubt that the normal case. Peri -- Original Message -- From: Mike Nickerson via EV ev@lists.evdl.org To: Ben Goren b...@trumpetpower.com; Electric Vehicle Discussion List ev@lists.evdl.org Sent: 15-Jan-15 9:04:35 PM Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT) I have one of the heat pump water heaters. It basically looks like a normal water heater with a small heat pump on top. They blow the cooler air out the top of the heat pump, so they can indeed be used to help with cooling in the summer. You need airflow around the area of the water heater to take advantage of the cooler air coming from the heat pump. Mike On January 14, 2015 9:39:18 AM MST, Ben Goren via EV ev@lists.evdl.org wrote: On Jan 12, 2015, at 8:35 PM, Robert Bruninga bruni...@usna.edu wrote: Compare the 60% efficiency of the PV/Heatpump water heater to the 50% losses half the year of the 70% thermal panels and higher cost and the PV panels with heatpump water heating win hands down. I hadn't heard of heat pump water heaters before this discussion. Something like that could, indeed, tip the balance. What happens to the cold side of the heat pump? Can that be used to reduce air conditioning load in summer? As of a few years ago, the return on investment, the payback time, for solar hot water was better than that of PV -- and that included maintenance every few years, electricity to heat the water on cloudy days (though much less electricity since you still get a substantial amount of warming), and so on. But it's obviously a rapidly-evolving field. If heat pumps really are coming to water heaters, that's huge not just for PV adopters but energy efficiency across the spectrum. If my own system lasts a few more years -- and there's no reason it shouldn't last a few times a few more years -- then it'll have paid for itself. Be nice to make a sizable profit off of it by getting it to last that few times a few more years, but, if it dies prematurely, I suppose an all-electric replacement will have to be on the short list as well as a drop-in equivalent replacement. b ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/ group/NEDRA) ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/ group/NEDRA) -- next part -- An HTML attachment was scrubbed... URL: http://lists.evdl.org/private.cgi/ev
Re: [EVDL] EV Demand Response - (solar-thermal-NOT-2)
Isn't it 8 LBS per gal? If I am not mistaken - the biggest factor in heating a pool is not the initial temp step (which is what you calculated) but the continuous and extremely large loss of heat to ambient due to evaporation and simply no insulation (unless you apply a cover every time you do not use it, which makes sense) but even then there is only a tiny bit of insulation, you are mostly removing the evaporation losses. Note that evaporation losses can cause the water temp to be *lower* than ambient if not constantly heated, similar to wind chill factor. Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: cwa...@proxim.comPrivate: http://www.cvandewater.com Skype: cor_van_de_water XoIP: +31877841130 Tel: +1 408 383 7626Tel: +91 (040)23117400 x203 -Original Message- From: EV on behalf of Robert Bruninga via EV Sent: Sat 1/17/2015 8:12 AM To: robert winfield Cc: Electric Vehicle Discussion List Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT-2) there is 1 place at least solar thermal wins. Heating swimming pools! But all that rooftop thermal energy is doing nothing during fall, winter and spring? Does it help power the EV? It might be interesting to do some numbers. Im curious... You may be right. Pool thermal heat simply needs a lot of pipe on the roof and are pretty low cost.. But could we make these assumptions... Lets assume 19,000 gallons X 7 lbs/gal X 20 degrees = 2,660,000 BTu divided by 3400 Btu per kWh and we get about 780 kWh needed to heat that water over about 3 months?. (doing not much the other 9 months, nor doing much once the water is already hot). Now, a modest 600 watt solar PV array (just three panels) can also produce about 780 kWh per year. And cost about $600 (DIY) or about $2000 contractor installed. So how does the cost of the pool heater compare? How does the roof area of the thermal pipes compare to the 50 sqft of the PV? If PV and a heatpump water heater were used, you could heat the pool to that same amount with a SINGLE 18 sqft solar panel. How does that compare? Add another $1500 to the cost for the heatpump. The point is that the same roof area as the pool heater when used instead for PV, would not only heat the pool, but also power the EV's and power some of the house too (maybe). Im curious...? Thanks BOb, WB4APR On Sat, Jan 17, 2015 at 10:37 AM, robert winfield winfield...@yahoo.com wrote: there is 1 place at least solar thermal wins. Heating swimming pools! I accidentally got my 19,000+ gallon pool up to 99 degrees F last labor day using only rooftop solar otherwise, i agree about PV, having PV since 1999 -- *From:* Robert Bruninga via EV ev@lists.evdl.org *To:* ev@lists.evdl.org *Sent:* Wednesday, January 14, 2015 1:34 PM *Subject:* Re: [EVDL] EV Demand Response - (solar-thermal-NOT-2) My point was that if the energy source is FREE, people don't care how much it takes or what its efficiency is. They'll use whatever is cheapest; not the most efficient. Well, we completely disagree. We are talking about rooftop solar. The system to use that solar energy is NOT free. It costs, and it costs big. And only someone with tightly held obsolete beliefs would cling to outdated inefficient conversion of that solar energy only to heat. Solar Thermal is really, really dead for the average homeowner. You were correct 10 years ago, but by 2006 PV broke even with solar water heating and now PV wins hands down. Remember, in the last decade PV solar has come down in cost 10-to-1. How much usable energy you get out of the roof divided by how much solar energy falls on that roof is a definition of EFFICIENCY. Most single-family homes probably *do* have enough roof area to provide all their energy needs. Simply *not* true in most places! You are talking about all. When you consider that all of our energy needs includes ELECTRICITY, HEATING, COOLING, and EV CHARGING, then there are VERY FEW average homes in America that can meet all of their energy needs only on their roof. Period. Go start covering your availalable roof with in-efficinent expensive thermal system, and STOP BURNING ANY OTHER FOSSIL FUEL for HEAT or DRIVING cars, and see how quickly you run out of space. You'll want PV if you do the numbers right on a year-round basis. Solar THERMAL costs more, is harder to install, requires more maintenance and delivers less (on an annual basis) in every way than the same area of today's PV (and heatpump technology). Do the math. Bob, Wb4APR -Original Message- From: Lee Hart [mailto:leeah...@earthlink.net] Sent: Wednesday, January 14, 2015 10:15 AM To: Robert Bruninga Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT) Lee Hart wrote: I think the word you want is return on investment; not efficiency. Robert Bruninga wrote: Nope. Most people only have so much
Re: [EVDL] EV Demand Response - (solar-thermal-NOT-2)
Pool heating does indeed work - because the system does not have to meet the same requirements. It is not a sanitary system and there is no need to protect from backfeeding the potable water supply of the municipality. The equipment - all of it, is significantly less expensive. The customers are generally more well to do - they can afford a swimming pool, and so on. The payback comes more quickly and the customer may not even care about it. On Sat, Jan 17, 2015 at 10:37 AM, robert winfield via EV ev@lists.evdl.org wrote: there is 1 place at least solar thermal wins. Heating swimming pools! I accidentally got my 19,000+ gallon pool up to 99 degrees F last labor day using only rooftop solarotherwise, i agree about PV, having PV since 1999 From: Robert Bruninga via EV ev@lists.evdl.org To: ev@lists.evdl.org Sent: Wednesday, January 14, 2015 1:34 PM Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT-2) My point was that if the energy source is FREE, people don't care how much it takes or what its efficiency is. They'll use whatever is cheapest; not the most efficient. Well, we completely disagree. We are talking about rooftop solar. The system to use that solar energy is NOT free. It costs, and it costs big. And only someone with tightly held obsolete beliefs would cling to outdated inefficient conversion of that solar energy only to heat. Solar Thermal is really, really dead for the average homeowner. You were correct 10 years ago, but by 2006 PV broke even with solar water heating and now PV wins hands down. Remember, in the last decade PV solar has come down in cost 10-to-1. How much usable energy you get out of the roof divided by how much solar energy falls on that roof is a definition of EFFICIENCY. Most single-family homes probably *do* have enough roof area to provide all their energy needs. Simply *not* true in most places! You are talking about all. When you consider that all of our energy needs includes ELECTRICITY, HEATING, COOLING, and EV CHARGING, then there are VERY FEW average homes in America that can meet all of their energy needs only on their roof. Period. Go start covering your availalable roof with in-efficinent expensive thermal system, and STOP BURNING ANY OTHER FOSSIL FUEL for HEAT or DRIVING cars, and see how quickly you run out of space. You'll want PV if you do the numbers right on a year-round basis. Solar THERMAL costs more, is harder to install, requires more maintenance and delivers less (on an annual basis) in every way than the same area of today's PV (and heatpump technology). Do the math. Bob, Wb4APR -Original Message- From: Lee Hart [mailto:leeah...@earthlink.net] Sent: Wednesday, January 14, 2015 10:15 AM To: Robert Bruninga Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT) Lee Hart wrote: I think the word you want is return on investment; not efficiency. Robert Bruninga wrote: Nope. Most people only have so much roof available for solar energy. And it is not enough for our total energy needs. So it is very important how much of that surface area you turn into retail value energy and is very much an efficiency determination. You are still using efficiency in place of other figures of merit. Here, you're talking about economics; not efficiency. What does it COST, versus how much money can I GET for it. That's return on investment. Most single-family homes probably *do* have enough roof area to provide all their energy needs, regardless of the PV cell's efficiency. Efficiency measures how much energy you get out divided by how much energy YOU put in. Yes, how much do you get out VERSUS how much the SUN puts in. My point was that if the energy source is FREE, people don't care how much it takes or what its efficiency is. They'll use whatever is cheapest; not the most efficient. They decide based on economics; not efficiency. Solar thermal makes sense if you want heat. It's really GOOD at making heat! Which I don't need 7 months of the year. But I do! I live in Minnesota, where we spend more on heat than we do on electricity. Do not assume that what is best for you is best for everybody. There is a place for both PV to make electricity, and solar thermal to make heat. -- Ingenuity gets you through times of no money better than money will get you through times of no ingenuity. -- Terry Pratchett -- Lee Hart, 814 8th Ave N, Sartell MN 56377, leeah...@earthlink.net ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA ( http://groups.yahoo.com/group/NEDRA) -- next part -- An HTML attachment was scrubbed... URL: http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150117/5a4bf6b7/attachment.htm
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
Peri Hartman via EV wrote: Lee, you're always so spot on but this time I'm going to disagree - a little. Efficiency of PV does matter. You have to buy the units, so the more efficient they are the less space they will take to generate the same amount of watts. Most people don't have unlimited space, so space does make a difference. It could also make a difference in purchase cost. Fewer panels mean less mounting hardware and less electrical work. Also fewer units could mean less overall cost for the PV units, themselves. Oh, I agree! I just think that if you're buying based on price, then look at *price* (not efficiency). Of course, this should be the installed price, and not just that of the panels alone. Or, you may want to buy based on other factors. Maybe they have to fit within a certain maximum size, or you need to generate a certain amount of power. Then efficiency becomes more important. When people make a big purchase, they need to be very clear about their goals. It's all too easy to kid ourselves, or rationalize, or oversimplify. (I *say* I bought this car to save gas, but I really bought it because I always wanted a red sports car). -- You never change things by fighting the existing reality. To change something, build a new model that makes the existing model obsolete. -- R. Buckminster Fuller -- Lee Hart, 814 8th Ave N, Sartell MN 56377, leeah...@earthlink.net ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
On Jan 14, 2015, at 6:13 AM, Robert Bruninga via EV ev@lists.evdl.org wrote: Most people only have so much roof available for solar energy. And it is not enough for our total energy needs. On the contrary. To within back-of-the-envelope precision, the residential rooftop surface area in the US alone receives enough solar energy, at today's off-the-shelf hardware store efficiencies, to provide all the energy needs for the entire planet. Electricity and transportation and manufacturing and everything else included for the whole population, just from residential US rooftops. Of course, it's not hard to find examples of homes that fall far short. An apartment in a skyscraper in the middle of Manhattan, for example, or somebody at the bottom of a canyon in the middle of a forest in Alaska. But the general rule is for people to have at least a few times as much surface area as they need for themselves, with lots and lots having several times as much as they need. Here's a good article on the subject, including a map that shows half a dozen hypothetical 8% efficiency PV installations, each of which by itself is enough for the entire planet: http://physics.ucsd.edu/do-the-math/2011/12/wind-fights-solar/ So, though there will certainly be edge cases where photovoltaic efficiency is the biggest concern -- with NASA leading the charge -- in the overwhelming majority of situations, it's the financial return on investment that's going to decide how best to make use of this particular abundant resource. Solar thermal makes sense if you want heat. It's really GOOD at making heat! Which I dont need 7 months of the year. Your tap water is 120°F for seven months of the year? And which I do need in the winter when it is producing HALF the heat for its size. Even if your solar thermal unit is only able to raise the temperature in the tank to 80°F, it takes much, much less electricity to heat 80°F water to 120°F than it does to heat 40°F water to 120°F. Again, the efficiency of new generations of heat pump water heaters may well change the financial equation, but, even if it does, it's not for the reasons you're giving. Cheers, b -- next part -- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 801 bytes Desc: Message signed with OpenPGP using GPGMail URL: http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150115/053a15a7/attachment.pgp ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
On 01/14/2015 11:39 AM, Ben Goren via EV wrote: I hadn't heard of heat pump water heaters before this discussion. Something like that could, indeed, tip the balance. What happens to the cold side of the heat pump? Can that be used to reduce air conditioning load in summer? Certainly, depending on where it's located. Mine is in the basement where, unfortunately now, it's keeping it quite chilly. It was 56 down there yesterday. But in the summer it helps keep it cool and helps dehumidify it. I have a dehumidifier that runs almost constantly all summer. The water heater generates about 5 gallons of water every 2 weeks so that's got to be helping. As of a few years ago, the return on investment, the payback time, for solar hot water was better than that of PV -- and that included maintenance every few years, electricity to heat the water on cloudy days (though much less electricity since you still get a substantial amount of warming), and so on. But it's obviously a rapidly-evolving field. If heat pumps really are coming to water heaters, that's huge not just for PV adopters but energy efficiency across the spectrum. Absolutely. My GE GeoSpring has a 2.4 energy factor. (You can also buy stand-alone heat pumps that you plumb inline with a standard resistance water heater.) I think, as others have said, that the plummeting price of PV has really tipped the scale and when you add in the improving efficiency of heat pumps it really falls over. --Rick ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
I agree that the improvements in air source heat pumps over the last couple decades, with operation down to as low as -25 F (albeit at low COP) has been a game changer. For one thing, I think they have made ground source heat pumps non-competitive due to their much higher cost. But I am not so sure they are always the best solution. I've looked at this for my house, and this specific case illustrates some of the variables. I can build a solar thermal system, collectors, pumps, insulated storage tank and plumbing, with 200 ft^2, collector area for less than $3k. This system will provide about 33kWh, 112,600 BTU, of heat to the storage tank per day (50% efficiency, measured), and about 30kWh into the house assuming a small amount of loss in the plumbing to the liquid-air heat exchangers. Using a cost of around $2.00 per Watt owner-installed, including racks, inverter, wiring, etc), this $3k would purchase about a 1.5kW PV system (example prices: http://www.wholesalesolar.com/gridtie.html#SolarSkySolarWorld). In my area that would supply about 7kWh electric per day yearly average, based on 6 years of data on my 5.6kW system. Heat pumps have to be purchased to turn this into heat into the house. An 8kW (27,000 BTU) heat pump is around $3k (for example: https://www.acwholesalers.com/Fujitsu-Air-Conditioners/AOU24RLXFZ-ASU9RLF-ASU9RLF-ASU9RLF-27000-BTU-18-SEER-Ductless-HeatPump/14513.ac?gclid=CLb7ifC5lsMCFdgHgQod_7UAIg). With COP of 3 this would deliver about 21kWh of heat using the 7kWh of electric per day, about 30% less than the solar thermal. But as someone said, I may use that power year around, but not the heat from the solar thermal. In our area we need to heat about 7 months of the year. The 200 ft^2 collector would only supply part of the energy required to heat the house over most of the winter, so I would use the full output over at least 5 of the 7 months. So for 5 months of the year I get 30kWh from solar thermal, and about 20kWh from PV. For the other 7 months I get nothing from solar thermal (not quite, some used for about 2 months) and 7kWh per day, or about $0.84 per day ($.12/kWh) from solar PV, or about $175.00 per year. I had to pay an additional $3k for the solar PV and heat pump system, which would be paid back in about 17 years at current utility rates. After that the PV/heat pump system would save me $175 per year in electric costs at current rates if I use its full output year round, or the utility pays me retail rate for surplus electric I supply. But I am not going to use that full output over the rest of the year unless I run AC enough during the 7 months to use the same energy I used from the system for heating during the 5 months of winter. I don’t. I just open the windows at night. In addition, we have net metering in my state, balanced over a year. So any surplus I have supplied at the end of the year is tossed out, I get no payment for it, so I wouldn’t gain $175 per year to pay back the $3k high cost of the PV/heat pump system and bank after that. In this case I pay twice as much for the solar PV/heat pump system and get less roi from it over a year since I won’t get paid for most of the surplus electric. In my specific case the solar thermal looks like a better roi. It also can be set up to run the pumps off of batteries which are charged by solar, so independent of the grid. A consideration where I live since the power goes out around a half dozen times per year. With grid tied PV and heat pump I would not have heat at these times unless I purchase a backup generator, or a different inverter and battery backup, further increasing cost. I think this is a complex calculation with many dependencies, such as available solar insolation, type of dwelling, type of metering by the utility, use of AC, installation costs (diy or not), etc, which can vary greatly with user and location. It is impossible to give a simple answer that is accurate for most users in most areas. Each case needs to be examined in detail. -- View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Re-EV-Demand-Response-solar-thermal-NOT-tp4673447p4673482.html Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com. ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
Not that it would make a huge difference, but I question the value of a heat pump H/W heater in winter. If it's taking heat from your garage or basement, that is ultimately taking some heat from your heated spaces, which means you're simply using more energy elsewhere. If you could somehow duct the air intake from outside during winter, then it would be doing the best job it could. In summer, no doubt a true benefit. Before you argue that I'm wroing, consider this. If the air outside your garage is colder than inside and the H/W tank is cooling the garage air in exchange for heating the water, either the garage temp will drop to less than the outside or warm air will be drawn from the home's heated spaces. If you are truly insulated, then the former will happen and you will have the equivalent of ducting intake from outside. I doubt that the normal case. Peri -- Original Message -- From: Mike Nickerson via EV ev@lists.evdl.org To: Ben Goren b...@trumpetpower.com; Electric Vehicle Discussion List ev@lists.evdl.org Sent: 15-Jan-15 9:04:35 PM Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT) I have one of the heat pump water heaters. It basically looks like a normal water heater with a small heat pump on top. They blow the cooler air out the top of the heat pump, so they can indeed be used to help with cooling in the summer. You need airflow around the area of the water heater to take advantage of the cooler air coming from the heat pump. Mike On January 14, 2015 9:39:18 AM MST, Ben Goren via EV ev@lists.evdl.org wrote: On Jan 12, 2015, at 8:35 PM, Robert Bruninga bruni...@usna.edu wrote: Compare the 60% efficiency of the PV/Heatpump water heater to the 50% losses half the year of the 70% thermal panels and higher cost and the PV panels with heatpump water heating win hands down. I hadn't heard of heat pump water heaters before this discussion. Something like that could, indeed, tip the balance. What happens to the cold side of the heat pump? Can that be used to reduce air conditioning load in summer? As of a few years ago, the return on investment, the payback time, for solar hot water was better than that of PV -- and that included maintenance every few years, electricity to heat the water on cloudy days (though much less electricity since you still get a substantial amount of warming), and so on. But it's obviously a rapidly-evolving field. If heat pumps really are coming to water heaters, that's huge not just for PV adopters but energy efficiency across the spectrum. If my own system lasts a few more years -- and there's no reason it shouldn't last a few times a few more years -- then it'll have paid for itself. Be nice to make a sizable profit off of it by getting it to last that few times a few more years, but, if it dies prematurely, I suppose an all-electric replacement will have to be on the short list as well as a drop-in equivalent replacement. b ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
Mine has a button that can switch it to simple resistive heat. I usually push that in the winter. Mike On January 16, 2015 5:47:20 PM MST, Peri Hartman via EV ev@lists.evdl.org wrote: Not that it would make a huge difference, but I question the value of a heat pump H/W heater in winter. If it's taking heat from your garage or basement, that is ultimately taking some heat from your heated spaces, which means you're simply using more energy elsewhere. If you could somehow duct the air intake from outside during winter, then it would be doing the best job it could. In summer, no doubt a true benefit. Before you argue that I'm wroing, consider this. If the air outside your garage is colder than inside and the H/W tank is cooling the garage air in exchange for heating the water, either the garage temp will drop to less than the outside or warm air will be drawn from the home's heated spaces. If you are truly insulated, then the former will happen and you will have the equivalent of ducting intake from outside. I doubt that the normal case. Peri -- Original Message -- From: Mike Nickerson via EV ev@lists.evdl.org To: Ben Goren b...@trumpetpower.com; Electric Vehicle Discussion List ev@lists.evdl.org Sent: 15-Jan-15 9:04:35 PM Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT) I have one of the heat pump water heaters. It basically looks like a normal water heater with a small heat pump on top. They blow the cooler air out the top of the heat pump, so they can indeed be used to help with cooling in the summer. You need airflow around the area of the water heater to take advantage of the cooler air coming from the heat pump. Mike On January 14, 2015 9:39:18 AM MST, Ben Goren via EV ev@lists.evdl.org wrote: On Jan 12, 2015, at 8:35 PM, Robert Bruninga bruni...@usna.edu wrote: Compare the 60% efficiency of the PV/Heatpump water heater to the 50% losses half the year of the 70% thermal panels and higher cost and the PV panels with heatpump water heating win hands down. I hadn't heard of heat pump water heaters before this discussion. Something like that could, indeed, tip the balance. What happens to the cold side of the heat pump? Can that be used to reduce air conditioning load in summer? As of a few years ago, the return on investment, the payback time, for solar hot water was better than that of PV -- and that included maintenance every few years, electricity to heat the water on cloudy days (though much less electricity since you still get a substantial amount of warming), and so on. But it's obviously a rapidly-evolving field. If heat pumps really are coming to water heaters, that's huge not just for PV adopters but energy efficiency across the spectrum. If my own system lasts a few more years -- and there's no reason it shouldn't last a few times a few more years -- then it'll have paid for itself. Be nice to make a sizable profit off of it by getting it to last that few times a few more years, but, if it dies prematurely, I suppose an all-electric replacement will have to be on the short list as well as a drop-in equivalent replacement. b ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
Since the Water Heater is a storage tank type, it also leaks heat back to its environment and needs regular re-heating. Since that is essentially a closed system, your garage may both be cooled (de-humidified!) by the heat pump and subsequently warmed up by the heat leaking from the vessel back into its ambient. Of course there is a net flow of heat out of your garage/basement when you open a hot water tap somewhere in the home, but there is also the loss in the heatpump that is adding to the heating of your garage/basement. It is simple to look at your garage as a closed system and calculate the energy in and out. If the amount of energy as hot water that you pull out of the garage is larger than the energy going into the garage as electric power, then the garage is cooled by the heat pump WH. If not, the garage is heated up by the WH, because there must be a balance of energy. Cor van de Water Chief Scientist Proxim Wireless Corporation http://www.proxim.com Email: cwa...@proxim.comPrivate: http://www.cvandewater.com Skype: cor_van_de_water XoIP: +31877841130 Tel: +1 408 383 7626Tel: +91 (040)23117400 x203 -Original Message- From: EV on behalf of Peri Hartman via EV Sent: Fri 1/16/2015 4:47 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT) Not that it would make a huge difference, but I question the value of a heat pump H/W heater in winter. If it's taking heat from your garage or basement, that is ultimately taking some heat from your heated spaces, which means you're simply using more energy elsewhere. If you could somehow duct the air intake from outside during winter, then it would be doing the best job it could. In summer, no doubt a true benefit. Before you argue that I'm wroing, consider this. If the air outside your garage is colder than inside and the H/W tank is cooling the garage air in exchange for heating the water, either the garage temp will drop to less than the outside or warm air will be drawn from the home's heated spaces. If you are truly insulated, then the former will happen and you will have the equivalent of ducting intake from outside. I doubt that the normal case. Peri -- Original Message -- From: Mike Nickerson via EV ev@lists.evdl.org To: Ben Goren b...@trumpetpower.com; Electric Vehicle Discussion List ev@lists.evdl.org Sent: 15-Jan-15 9:04:35 PM Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT) I have one of the heat pump water heaters. It basically looks like a normal water heater with a small heat pump on top. They blow the cooler air out the top of the heat pump, so they can indeed be used to help with cooling in the summer. You need airflow around the area of the water heater to take advantage of the cooler air coming from the heat pump. Mike On January 14, 2015 9:39:18 AM MST, Ben Goren via EV ev@lists.evdl.org wrote: On Jan 12, 2015, at 8:35 PM, Robert Bruninga bruni...@usna.edu wrote: Compare the 60% efficiency of the PV/Heatpump water heater to the 50% losses half the year of the 70% thermal panels and higher cost and the PV panels with heatpump water heating win hands down. I hadn't heard of heat pump water heaters before this discussion. Something like that could, indeed, tip the balance. What happens to the cold side of the heat pump? Can that be used to reduce air conditioning load in summer? As of a few years ago, the return on investment, the payback time, for solar hot water was better than that of PV -- and that included maintenance every few years, electricity to heat the water on cloudy days (though much less electricity since you still get a substantial amount of warming), and so on. But it's obviously a rapidly-evolving field. If heat pumps really are coming to water heaters, that's huge not just for PV adopters but energy efficiency across the spectrum. If my own system lasts a few more years -- and there's no reason it shouldn't last a few times a few more years -- then it'll have paid for itself. Be nice to make a sizable profit off of it by getting it to last that few times a few more years, but, if it dies prematurely, I suppose an all-electric replacement will have to be on the short list as well as a drop-in equivalent replacement. b ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
On Jan 16, 2015, at 8:20 PM, Cor van de Water via EV ev@lists.evdl.org wrote: If the amount of energy as hot water that you pull out of the garage is larger than the energy going into the garage as electric power, then the garage is cooled by the heat pump WH. Seems like the proper answer is ducting to the outside with a reversible fan. When you want to cool your indoors, draw air from outside and vent it inside. When you want to heat your indoors, draw air from inside and vent it outside. Or, if it's excessively cold outside, draw air from inside and also vent it inside and / or switch to resistive heating. Having never even heard of heatpump water heaters until a day or three ago, I wouldn't begin to speculate on how suited off-the-self models are to such a configuration. b -- next part -- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 801 bytes Desc: Message signed with OpenPGP using GPGMail URL: http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150116/ab2d1d29/attachment.pgp ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
On Jan 12, 2015, at 8:35 PM, Robert Bruninga bruni...@usna.edu wrote: Compare the 60% efficiency of the PV/Heatpump water heater to the 50% losses half the year of the 70% thermal panels and higher cost and the PV panels with heatpump water heating win hands down. I hadn't heard of heat pump water heaters before this discussion. Something like that could, indeed, tip the balance. What happens to the cold side of the heat pump? Can that be used to reduce air conditioning load in summer? As of a few years ago, the return on investment, the payback time, for solar hot water was better than that of PV -- and that included maintenance every few years, electricity to heat the water on cloudy days (though much less electricity since you still get a substantial amount of warming), and so on. But it's obviously a rapidly-evolving field. If heat pumps really are coming to water heaters, that's huge not just for PV adopters but energy efficiency across the spectrum. If my own system lasts a few more years -- and there's no reason it shouldn't last a few times a few more years -- then it'll have paid for itself. Be nice to make a sizable profit off of it by getting it to last that few times a few more years, but, if it dies prematurely, I suppose an all-electric replacement will have to be on the short list as well as a drop-in equivalent replacement. b ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
Lee, you're always so spot on but this time I'm going to disagree - a little. Efficiency of PV does matter. You have to buy the units, so the more efficient they are the less space they will take to generate the same amount of watts. Most people don't have unlimited space, so space does make a difference. It could also make a difference in purchase cost. Fewer panels mean less mounting hardware and less electrical work. Also fewer units could mean less overall cost for the PV units, themselves. Peri -- Original Message -- From: Lee Hart via EV ev@lists.evdl.org To: Electric Vehicle Discussion List ev@lists.evdl.org Sent: 13-Jan-15 9:03:42 AM Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT) Robert Bruninga via EV wrote: Solar Thermal makes no sense anymore. Compare 70% efficiency (ONLY 5 months of the year) for a net of 29% to: PV that is 18% year round AND when used to drive a Heatpump with a COP of 2.5 gives a net efficiency of producing 45% HEAT. Or look at it this way. Every single day that your house is not using 100% of every BTU available, you are losing solar energy that could be generating electricity at full market rates! I think the word you want is return on investment; not efficiency. Efficiency measures how much energy you get out divided by how much energy YOU put in. When you're getting the energy for free (the sun), it doesn't really matter what your conversion efficiency is. The energy you didn't collect isn't costing you anything, and it isn't lost -- it's doing what it always does and is heating the environment. Solar thermal makes sense if you want heat. It's really GOOD at making heat! Solar PV makes sense if you want electricity. It's not all that efficient (10-15%); but that's still better than using some other method (wind, thermal) that then needs a second conversion process to give you electricity. -- Ingenuity gets you through times of no money better than money will get you through times of no ingenuity. -- Terry Pratchett -- Lee Hart, 814 8th Ave N, Sartell MN 56377, leeah...@earthlink.net ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
Solar Thermal makes no sense anymore. Compare 70% efficiency (ONLY 5 mos of the year) for a net of 29% to PV that is 18% year round AND when used to drive a Heatpump with a COP of 2.5 gives a net efficiency of producing 45% HEAT. AND the other 7 months provides COOLING or retail value for the electricity. I think the word you want is return on investment; not efficiency. Nope. Most people only have so much roof available for solar energy. And it is not enough for our total energy needs. So it is very important how much of that surface area you turn into retail value energy and is very much an efficiency determination. Efficiency measures how much energy you get out divided by how much energy YOU put in. Yes, how much do you get out VERSUS how much the SUN puts in. The energy you didn't collect isn't costing you anything, and it isn't lost -- it's doing what it always does and is heating the environment. I'd rather be getting 15 cents per kWh for evrey square foot I have, than throwing it away on square footage that only produces usable heat for only a few months a year and then wastes it all the rest. Solar thermal makes sense if you want heat. It's really GOOD at making heat! Which I dont need 7 months of the year. And which I do need in the winter when it is producing HALF the heat for its size. And which produces DOUBLE the heat in the summer when I need it NOT AT ALL and which I cannot STORE for 6 months until I do. With PV you get full retail value for every kWh every month of they year and you can save 100% of the excess you get in the summer for when you might need it in the winter. And with a heat pump, you get 2 to 4 times the heat that you stored! AND you can charge your EV for free from the excess electricity. You cant do that with heat. Forget it. WIth the 10-to-1 reduction in PV costs over the last decade, it is time to let go of solar thermal. It makes no economical sense for the investment. PASSIVE solar design of buildings does make sense but that is direct sun to the inside. Not Solar Thermal. For solar energy collection, only PV makes sense since it can be used for ANYTHING. Not just heat in the winter. Bob, WB4APR. Solar PV makes sense if you want electricity. It's not all that efficient (10-15%); but that's still better than using some other method (wind, thermal) that then needs a second conversion process to give you electricity. -- Ingenuity gets you through times of no money better than money will get you through times of no ingenuity. -- Terry Pratchett -- Lee Hart, 814 8th Ave N, Sartell MN 56377, leeah...@earthlink.net ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/ group/NEDRA) -- next part -- An HTML attachment was scrubbed... URL: http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150114/afe0413f/attachment.htm ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
Robert Bruninga via EV wrote: Solar Thermal makes no sense anymore. Compare 70% efficiency (ONLY 5 months of the year) for a net of 29% to: PV that is 18% year round AND when used to drive a Heatpump with a COP of 2.5 gives a net efficiency of producing 45% HEAT. Or look at it this way. Every single day that your house is not using 100% of every BTU available, you are losing solar energy that could be generating electricity at full market rates! I think the word you want is return on investment; not efficiency. Efficiency measures how much energy you get out divided by how much energy YOU put in. When you're getting the energy for free (the sun), it doesn't really matter what your conversion efficiency is. The energy you didn't collect isn't costing you anything, and it isn't lost -- it's doing what it always does and is heating the environment. Solar thermal makes sense if you want heat. It's really GOOD at making heat! Solar PV makes sense if you want electricity. It's not all that efficient (10-15%); but that's still better than using some other method (wind, thermal) that then needs a second conversion process to give you electricity. -- Ingenuity gets you through times of no money better than money will get you through times of no ingenuity. -- Terry Pratchett -- Lee Hart, 814 8th Ave N, Sartell MN 56377, leeah...@earthlink.net ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
On Jan 12, 2015, at 6:32 AM, Robert Bruninga via EV ev@lists.evdl.org wrote: Solar Thermal makes no sense anymore. Not for living space, but it makes plenty of sense for hot water. b ___ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
Solar Thermal makes no sense anymore. Compare 70% efficiency (ONLY 5 months of the year) for a net of 29% to: PV that is 18% year round AND when used to drive a Heatpump with a COP of 2.5 gives a net efficiency of producing 45% HEAT. Or look at it this way. Every single day that your house is not using 100% of every BTU available, you are losing solar energy that could be generating electricity at full market rates! RELATED TO EV's, that's why EV's are adding heatpumps instead of resistance heat. Bob, WB4APR On Sun, Jan 11, 2015 at 7:08 PM, Michael Ross via EV ev@lists.evdl.org wrote: A few years now, my business at NC State has been to test solar thermal collectors for certification. We also offer installation training and other CE classes for the industry: wind, PV, etc. To summarize, I don't there is much future for residential solar thermal. It is easy and efficient to collect heat from the sun in water, most collectors are 70% efficient, not much better, not much worse (except if they are total crap). The temperature of the fluid is not much use for anything but offsetting costs of water or space heating by other means. Simple as the collector is, the solar thermal system is far more complicated than a PV system: you have an electrical and control systems, plumbing, holes in the roof, maybe a heat exchanger (for a glycol circuit) instead of regular hot tank for wash water, or you have a drainback system that empties the collector when it it is not sunny. There is enough complication that the cost of installation is high, and many households simply don't need enough hot water to get any payback. Consider my home with just two people gone half the day; $20 to insulate the hot water tank is a much better value than $4k or $5k to get a collector and system installed. As PV gets more efficient and cost drops, it will be come much simpler and more cost effective to run the electric element in the hot tank. Residential solar thermal is dying. Eventually, PV my be comparable to the various solar space heating options. There is one nice simple solar thermal idea that gets oddly little attention and that is solar air heating collectors. We worked with a fellow in Florida who has a nice well thought out air collector's system. The front glass is a standard double pane picture window. All the materials were chosen for ready availability and cost - typical construction materials mostly. The system couldn't be simpler - it has a simple bimetallic thermostat that turns the fan on above 90F and off below. On Sun, Jan 11, 2015 at 3:43 PM, Peri Hartman via EV ev@lists.evdl.org wrote: I think a combo of PV panels and solar collectors would generally be the best solution, assuming you have the sun exposure. Currently PVs are not very efficient. I don't have any numbers of solar collectors but I'm pretty sure they can beat PVs several times over. Since home heating doesn't require electricity, that could be done more effectively with collectors. The EV and home appliances could be powered by PVs, to the extent possible. How much reduction in fossil fuel use would depend on how your power is generated and how you currently heat. In my case, home heating comes from natural gas (don't have any A/C) and almost all the electricity comes from hydro. Thus, the best way for me to reduce my carbon use (and reduce fracking) is to switch my home heating to a solar collector system. If your case is, say, electricity from 50% coal and 50% nuke, where as your heating is natural gas and cooling is electricity, then you may be better of prioritizing the electricity generation before the heating. Either way, the amount of area required to capture kWh-equivalents is going to be smaller for heating than for generating electricity until we have better PV technology. So, don't overlook installing collectors. Peri -- Original Message -- From: Peter Eckhoff via EV ev@lists.evdl.org To: Ben Goren b...@trumpetpower.com; Electric Vehicle Discussion List ev@lists.evdl.org Sent: 11-Jan-15 10:21:19 AM Subject: Re: [EVDL] EV Demand Response - (now Home solar) When I took a Solar Energy course way back when, my instructor said there was a rule of thumb for solar thermal heating. He said to take the square footage of the heated **area** and divide by 3 to produce a storage **volume** estimate. At the time, fist sized rocks were used to store the heat. Of course insulation, angle of the collectors to due south, etc. mattered. The idea was to pump a liquid through the collectors to the storage volume and then have a separate (or 3-way valve) to direct any heat from the storage volume to pipes radiating heat under the subflooring. Recently, I ran a parameterized commercial solar energy program with a similar system and the system came back saying I needed a 600 gallon tank for optimum
