The best way, and no-tech way to do grid-assist without a battery is similar to what I posted earlier. But here is a nutshell summary:
Electric Waterheater. Disconnect lower coil from AC mains. Connect to three solar panels in series (~100v) via the lower thermostat AND BYPASS CONTACTS with a 10 ohm +XuF capacitor arc suppression snubber. This will drive the 4800W (1 hour recovery) heater coil into an 800W (6 hour recovery) system. This then will fully use 6 hours worth of sun everyday. Done. Leave the top coil connected to the mains so that you always have the top half of hot water care-free whether the bottom half is heated by solar or not. Portable Heatpump/AC unit (120 VAC). Simply take two 275W solar panels pointed SE and two pointed SW wired in parallel to a 600W cheap grid-tie inverter. Connect the output of that inverter to the AC compressor wires. This way, it is never backfeeding the grid except when the thermostat turns on the compressor, and then the compressor absorbs all of the GT energy. The reason for splitting the array into SE and SW panels is so that you can provide the same 600W or so for twice as long and still not overload the inverter. Then you keep this portable heatpump/AC unit running all the time when the sun is up. Either for pre-cooling the house, or pre-warming it. The only thing that keeps this from being 100% use of your solar investment is when you don’t use the unit. But the energy is free, so having this unit in the main room of the house and having it on a timer to always run when the sun is shining, is an easy way to get grid-assisted free solar energy without being net-metered and without the hassle of a battery. WARNING: If you do not get the waterheater DC snubber circuit right, the arc when the thermostat opens will burn the contacts (into a short), overheat the waterheater on a day you don’t use any hot water and blow up the water heater (if the over pressure valve fails) and blow the thing through the roof of your house. The fail-safe solution to this is the same as for the portable AC/heatpump. First run the solar panels through a small GT inverter and connect the output of that to the heater coil after the thermostat. Then y ou can wire the line side of the thermostate to 120 VAC and have the advantage that even on cloudy days, the bottom of the heater will heat seamlessly from the main (over 6 hours). The added cost of $175 for the GT inverter (now needs to be a 1 kW GT microinverter to absorb 3 panels of energy) is worth the automatic always-have-hot-water mode. Bob, WB4APR *From:* Robert Bruninga <[email protected]> *Sent:* Sunday, July 14, 2019 5:38 PM *To:* Electric Vehicle Discussion List <[email protected]> *Cc:* Robert Bruninga <[email protected]> *Subject:* Re: [EVDL] Solar off grid with an EV? (DC AC/heatpumps and waterheating) These days, most new Air conditioners are variable speed for maximum efficiency. This means they rectify line voltage to DC and then run everything internally off of DC. This means you can run them on high voltage DC just as well as AC. Some manufacturers even advertise them that way. You can hook up 3 or 4 solar panels to them (DC at 90 to 120 VDC) and they will parallel into the DC system and run on sunshine or grid. And these are NOT special systems. They are regular low cost mini-split AC/Heatpump units that simply happen to run internally on rectified DC. These are an ideal use of solar in a non-grid tied system. But again, only of 50% value,because in the spring and fall, you dont need AC or heat and so your 4 solar panels are doing nothing. But using about 4 Solar panels for the bottom coil in a water heater are a good idea. You need hot water every day, and so this gives you 100% effectiveness of these 4 or so panels. Just be sure you fully understand the consequences of a switch (plazma) when switching DC. These are just some of the DIY uses of solar panels in the ARRL book http://aprs.org/Energy-Choices.html Bob On Mon, Jul 15, 2019 at 2:20 PM paul dove via EV <[email protected]> wrote: That's good, all the inverters I have seen disconnect the solar panels when the grid goes down so you loose power from your own system to protect line workers. I never liked that configuration. The last time we had a 3 day power outage was in August in Alabama. It was hot and muggy and no hot water.... oh and the gas pumps were out so you couldn't buy gasoline because the had electric fuel pumps. Some of the stations got generators and were pumping gas after a day but not all. On Monday, July 15, 2019, 8:40:54 AM CDT, Robert Bruninga via EV < [email protected]> wrote: > a $250 generator won’t power your house. Maybe a few appliances. > Can do mine. I need about 100W to power all the lights in the house that I need (20 or so LED's) I need about 250W to power the refrigerator (50% duty cycle) A small generator can do that nicely! I do not need anything else during grid down. But then I have not used a generator in years. I just plug the house into the 2 kW available from My Chevy Volt. Or the 1 kW from the Prius. Dont need no stinkin generator. Oh, and while the sun is up, I have 16 kW of solar power...(DC, but the Sunny Boy inverters now include 1.5kW of grid-down AC as well per inverter)... Bob, Wb4APR > > > On Jul 13, 2019, at 6:15 PM, Robert Bruninga via EV <[email protected]> > wrote: > > > > WHen you go grid-tie solar, nothing changes. you do the same thing you > did > > before. A $250 generator and a $15 can of gas is far more cost > effective > > to produce a few dollars worth of power outage comapred to a $13,000 > > battery to produce $2 worth of power (a 14 hour outage)... Bob > > > >> On Sun, Jul 14, 2019 at 7:05 PM paul dove <[email protected]> wrote: > >> > >> One thing I haven’t seen mentioned is power outage. If the grid goes > down > >> with net metering so does you solar. > >> > >> You have to be off-grid to stay powered when the grid fails. > >> > >> Sent from my iPhone > >> > >>> On Jul 14, 2019, at 11:16 AM, Robert Bruninga via EV < > [email protected]> > >> wrote: > >>> > >>> But why are you so determined to use batteies when the cost of grid > power > >>> is ditrt cheap. > >>> > >>> a 1kwh deep cycle lead acid battery might cost $100. It will store 10 > >>> cents of electricity per day. > >>> After one year it is SHOT. that is $100/365 days or about 27 cents per > >>> kWh. So you are paying TRIPLE the cost of electricity just for a > battery > >>> compared to just getting it from the grid? And this does not even > >> mention > >>> the cost of solar panels. This is purely battery storage costs. > >>> > >>> Even if you find magic battteries that can do 1000 discharges before > >>> replacement, that still is 10 cents per kWh storage cost and still does > >> not > >>> even count the cost of solar to get the energy inthe first place. > >>> > >>> AND, unless you do a full cycle of thebattery everyday, to use y our > >>> incoming solar, then you are not fully using your array.investment. > Sure > >>> you can throw away all kinds of money at this problem, but nothing > >> canbeat > >>> being grid-tied and a net meter. Just do it. Do a small system at > >>> contractor prices... then add panels at your leisure and at 20% of the > >> cost. > >>> > >>> bob > >>> On Sun, Jul 14, 2019 at 10:50 AM Peri Hartman via EV < > [email protected]> > >>> wrote: > >>> > >>>> Actually, I am proposing something simpler than a power wall - that > does > >>>> not feed back to the grid. Maybe that simplification doesn't reduce > the > >>>> cost of the battery system much, but it would reduce the legal paper > >>>> work down to a normal electrical permit. > >>>> > >>>> Peri > >>>> > >>>> ------ Original Message ------ > >>>> From: "Willie via EV" <[email protected]> > >>>> To: [email protected] > >>>> Cc: "Willie" <[email protected]> > >>>> Sent: 14-Jul-19 7:30:58 AM > >>>> Subject: Re: [EVDL] Solar off grid with an EV? (transformers) > >>>> > >>>>> > >>>>> > >>>>>> On 7/14/19 9:06 AM, Peri Hartman via EV wrote: > >>>>>> How hard would it be to build a battery system that normally > supplies > >>>> 100% of the domestic power but, when depleted, switches over to supply > >>>> domestic power from the grid ? Also, I think it would be safe > >> assumption, > >>>> or at least a reasonable simplification, to assume that the battery is > >>>> always sufficient for the load, except when depleted. The battery > would > >>>> always be charging from a solar array, never from the grid. > >>>>>> > >>>>>> It seems to me, a system like this would completely circumvent any > >>>> negative conditions imposed by power companies. Of course, once the > >> solar > >>>> panels fill the battery, excess production is lost. > >>>>> > >>>>> You have described a PowerWall. The battery is one or more units > that > >>>> will supply or charge 5kw and holds 13-14kwh. If about 11kwh will > carry > >>>> you over night and if you don't use more than 5kw over night, a single > >>>> battery unit will serve you. With good sun, day time self power use > >> can be > >>>> around 20kw, including car charging. > >>>>> > >>>>> In 5 or so months, I have bought less than 10kwh from my utility and > >> sold > >>>> them something like 10,000 kwh. That is with one battery unit. > >>>>> > >>>>> Cost installed was about $13k. For smooth operation, I am highly > >>>> dependent on the utility to accept my excess power. > >>>>> > >>>>> _______________________________________________ > >>>>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > >>>>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org > >>>>> Please discuss EV drag racing at 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 > >>>> Please discuss EV drag racing at 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/20190714/9cbd7158/attachment.html > >>> > >>> _______________________________________________ > >>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > >>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org > >>> Please discuss EV drag racing at 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/20190713/f4fdb073/attachment.html > > > > _______________________________________________ > > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > > Please discuss EV drag racing at 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 > Please discuss EV drag racing at NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > -------------- next part -------------- An HTML attachment was scrubbed... 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