> Since I really wanted a battery back-up... Everyone's situation is different, but I had to ask myself, how often do I lose power (and how quickly can I rig emergency power?)? Around here it is 99.95% reliable (average 4 hours per year outage). My typical home (1 kW average) then loses about 80 cents of electricity per year. Now how many thousands of dollars and maintenance and replacement of batteries for the rest of my life is worth 80 cents a year?
To me, its ludicrous to have home batteries... But, of course, I do. (Wife insists on it). SO I have 4 small marine batteries and a 2 kW inverter (total cost about $500) to power all the lights and the refrigerator overnight. (Though I have not used it EVER in the 4 years I have had solar). And since it may on average only happen once a year, I don't even bother with a charging system. If I ever used the system, and needed to charge those 48v worth of batteries, I have two clip leads that I will just clip from the 450v solar panels directly to the battery. The solar panels of course are current limited to about 7 amps, so they will drop to the 48 volts for charging just fine (human in the loop to disconnect when full). The only excitement is when I disconnect the clip lead and draw a nice welding arc. With 16 kW of solar panels (6 strings at 450v or so) I have 6 strings of 7 amps or 42 amps of DC suitable for charging ANY battery (of any voltage) during an Armageddon event indefinitely. And although I have done designs of an automatic switch over system and charge regulator... I just cannot justify the time investment to replace 80 cents of electrticity per year... Again, everone's situation is different. But there is nothing I hate worse in life than batteries. (except the one in the EV of course!) Oh, another reason I have never used the "home backup" is simply because I have a 1500W inverter in the Prius, and the few times I needed power, I just plug stuff into it. See http://aprs.org/FD-Prius-Power.html P.S. The above availability of LOTS of kW of DC solar is why I have encourage DIY folks to wire their 400-500v SERIES Strings PV with a center-tap so that with loss of grid, they can parallel the two halves and then get DOUBLE the current. In my case, that could make over 80 Amps of DC (at any voltage from 12 to over 200v) available for charging. Even on cloudy days, the 80 amps worth of solar will still produce 8 amps of charging (sun rise to sunset) which is alos fine for my 4 marine batteries. SO I never need more than overnight 12 hour battery storage for the refer and lights. Bob, WB4aPR -----Original Message----- From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of len moskowitz via EV Sent: Monday, May 04, 2015 8:26 PM To: Cor van de Water Cc: Electric Vehicle Discussion List Subject: Re: [EVDL] virtual power plant Cor wrote: > that is why - next week, someone will come to inspect my home > to > establish whether he wants to make a bid on delivering me a system > and I have already received a bid from SolarCity. I've had SolarCity and SunPower quote grid-tie PV systems for our home. Provided you have the cash available, it didn't make sense to do anything but buy the systems outright. They both came in at $4/watt installed, with SunPower offering a higher capacity system for our limited roof size. That was the main difference between them. Since I really wanted a battery back-up system like the one we had in our previous home, I asked SunPower if they could provide just their high efficiency solar panels, and I'd have a local contractor provide the rest of the system based on the Outback Radian inverters, charge controllers and monitors. The pricing they offered for panels-only was not at all competitive. It seems to me that they don't want to just sell panels. They want that $4/watt. Maybe now with the Tesla battery units becoming available, I can get SolarCity to quote a battery backup system. I still don't expect them to be price competitive. My impression is that they don't think that they need to be competitive. Len Moskowitz _______________________________________________ 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)
