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 heating. In this case, a liquid is being used to store the > heat > >> instead of rocks or sand. > >> > >> While not perfect, the idea is that PV will take care of local EV > driving > >> needs and the solar thermal will address a lot of winter heating needs. > The > >> more cloud cover and colder winter temperatures, the less energy it will > >> provide. > >> > >> On 1/10/2015 3:09 PM, Ben Goren via EV wrote: > >> > >>> On Jan 10, 2015, at 9:21 AM, tomw via EV <ev@lists.evdl.org> wrote: > >>> > >>> His book, Solar Hot > >>>> Water Heating, describes (among other systems) using solar hot water > >>>> collectors to heat a 2 ft thick layer of sand which is insulated > inside > >>>> the > >>>> house foundation with a concrete slab floor on top of it, giving over > >>>> one > >>>> hundred of metric tons of thermal mass for radiant floor heating. > Water > >>>> is > >>>> circulated through the sand with PEX tubing, starting around mid > August > >>>> to > >>>> heat it up for the winter. > >>>> > >>> Similarly, the most effective method of cooling for locations such as > >>> Arizona where I am also uses the Earth as an heat sink...and, of > course, > >>> also similarly only really make sense for new construction. But, yes -- > >>> done right, and you can live in arctic frigidity in the middle of > August > >>> for pennies per day. If whoever built the building had the foresight > to do > >>> things right.... > >>> > >>> But the good news is that there's insane amounts of energy available > >>> from the Sun such that simply covering a suitable fraction (and > generally a > >>> minority) of your roof space with generic PV panels results in a net > >>> surplus. And, if the grid is available to use as the equivalent of a > >>> battery, you can make an handsome profit that way if you've got > available > >>> capital to invest. Most can still make a profit, though nowhere near so > >>> handsome and with much more capital, going off the grid entirely. > >>> > >>> 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/20150110/fd0a3ee8/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) > >>> > >>> > >>> > >> _______________________________________________ > >> 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) > > > > > > > -- > Put this question to yourself: should I use everyone else to attain > happiness, or should I help others gain happiness? > *Dalai Lama * > > Tell me what it is you plan to do > With your one wild and precious life? > Mary Oliver, "The summer day." > > To invent, you need a good imagination and a pile of junk. > Thomas A. Edison > <http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> > > A public-opinion poll is no substitute for thought. > *Warren Buffet* > > Michael E. Ross > (919) 550-2430 Land > (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google > Phone > (919) 631-1451 Cell > (919) 513-0418 Desk > > michael.e.r...@gmail.com > <michael.e.r...@gmail.com> > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150111/a00a67ec/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) > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150112/9f5640ea/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)
