I would agree. Lower priced mass produced commodity AC appliances and lower wiring/switch/outlet costs will make up for the inverter inefficiencies. Keep in mind the amount of useful energy that you need to get out of a system and then choose components that will get you there. Max technical efficiency (kWh usefully used vs kWh produced by array, or kWh produced/sq. m) is unlikely to match max economic efficiency ($/kWh), rather there will be a range of choices with tradeoffs, some large, some small.
Even if you increase the size of your PV array by 10% to offset the inverter...you're only talking two extra 250 watt modules (500 W total) on 5 kW system. Parts cost can be under $1000 here ($2/watt). (You could also try increasing the array size to offset the losses from using a bit smaller DC wiring, if you really didn't want AC involved. There is going to be a financial sweet spot between various array sizes and the losses associated with a chosen wire size.) Another consideration: future inspectors and owners will likely appreciate the use of standardized equipment and techniques. The math may be a bit different if the electric loads are minimal (e.g. only efficient lights) and/or distances short (small cabin/trailer). On June 7, 2016 11:10:49 AM CDT, Larry Gales via EV <ev@lists.evdl.org> wrote: >Thanks, I was somewhat aware of the increased use of copper, but not to >the >extent that you specify, so it looks like AC is the way to go, even for >off-grid solar. > >On Tue, Jun 7, 2016 at 9:06 AM, robert winfield via EV ><ev@lists.evdl.org> >wrote: > >> my inverter (Omnion 2200) has 2 legs. +/- 186v DC (~370v) small >wires., >> inverted to 110v AC about ~8 amps with a 20 amp circuit breaker (made >back >> around 1995 - 1997 or so) >> >> From: Robert Bruninga via EV <ev@lists.evdl.org> >> To: Electric Vehicle Discussion List <ev@lists.evdl.org> >> Sent: Tuesday, June 7, 2016 10:39 AM >> Subject: Re: [EVDL] Off-grid solar house and electric car charging >> >> > If you build an off-grid solar house and use it for both your house >> > and charging your electric car, are there any disadvantages for >using >> > DC current (household appliances can all be converted to DC) and >> > avoiding AC since you are off the grid? You avoid the cost, >> > maintenance, and (slight) inefficiency of inverters, but are there >> > significant disadvantages to this approach? >> >> A big question is what voltage. Home solar typically uses high >voltage >> 300 to 600 VDC so that currents are less and smaller copper wire can >be >> used (think #12 standard wire). >> >> Remote, Off -grid DC systems typically operate no higher than 48 >volts. >> Right there is a 10 to 1 drop in voltage so a 100 to 1 increase in >cable >> losses. Now think big battery cables everywhere and a huge >investment in >> copper. >> >> Some people then drop to 12v to use many common 12 camping >accessories to >> live by. That then further multiplies wire losses by another eight >to one >> factor, or almost 800 times more losses for the same wire. >> >> So In most cases, it is far, far easier to accept the 5% Inverter >lossess >> and keep your house at the 120 VAC standard so you can use all >existing >> home wiring techniques and all existing home appliances and all >existing >> electrical things in the home than to deal with ALL specialized much >more >> expensive DC appliances and HUGELY expensive specialized wiring. >> >> Bob >> _______________________________________________ >> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >> http://lists.evdl.org/listinfo.cgi/ev-evdl.org >> Read EVAngel's EV News at http://evdl.org/evln/ >> 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/20160607/76fd9acb/attachment.htm >> > >> _______________________________________________ >> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >> http://lists.evdl.org/listinfo.cgi/ev-evdl.org >> Read EVAngel's EV News at http://evdl.org/evln/ >> Please discuss EV drag racing at NEDRA ( >> http://groups.yahoo.com/group/NEDRA) >> >> > > >-- >Larry Gales >-------------- next part -------------- >An HTML attachment was scrubbed... >URL: ><http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20160607/42526ed5/attachment.htm> >_______________________________________________ >UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub >http://lists.evdl.org/listinfo.cgi/ev-evdl.org >Read EVAngel's EV News at http://evdl.org/evln/ >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/20160607/579e4fd4/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
