Micro inverters are nice in other ways, you can build out your system over a long time whereas string inverters can't support adding a panel or two as your needs grow. The wiring is simpler and it is AC which does quench an arc better than 300 to 600 VDC. As you mentioned you have more freedom to place micro inverter panels. You can implement AC producing microinverter panels to off grid use and ignore a lot of the issues that come up with EV generating panels. In fact you could start small with some microinverters, and go to a string inverter system later and they would not conflict.
There are advantages and disadvantages to everything, optimal designs for one situation that are suboptimal in others. It takes a bit of homework to finds what works. This is pretty much OT so maybe better cease and desist. I wonder why you bring such harshness to conversations. It seems unnecessary, definitely unpleasant. On Jun 6, 2016 10:13 AM, "Robert Bruninga via EV" <ev@lists.evdl.org> wrote: > There are other better ways of avoiding inefficiency, I think. > One is that many panels are set up in series, which means > that if any one cell is covered by shade, the output of the > entire system is reduced RANT ON: True in paper-theory, but this is oft' repeated hogwash sales pitch by salesmen of microinverters is complete BS. Every, and I repeat EVERY solar panel, has not just ONE , but THREE or more bypass diodes that will automatically bypass any section (of 3) of a solar panel that is shaded. SO if you have a string of 10 panels in series, and one cell is completely shaded, you only lose 1/3rd of 1/10th of the array or only 3%. Not the 100% that the salesmen promote. This 3% is the EXACT same power you would lose with a microinverter! The microinverter operates at the panel level, and it too will see the 1/3rd drop when any one cell is blocked in one of its 3 sections. And there is no way whatsovever that panels do not have bypass diodes. THEY ARE ABSOLUTELY required. Because solar cells cannot tolerate a reverse bias more than about 10 volts or they DESTROY themselves. This is why the back of every 30 volt panel has THREE sections and each section has its OWN bypass diode. This it to protect that third of the panels cells from never seeing a reverse voltage greater than 10 volts. [ and as a side benefit, it also removes that shaded section from the string so that the rest of the array can still produce at full output. > . (Use a different inverter technology, > and set up your cells in parallel, to avoid this) No, that accomplishes nothing but to multiply your COPPER costs by a factor of 100! If you connect them in parallel, then you need wires to carry TEN times the current, and loss is a factor of CURRENT SQUARED. Hence you need 100 times the copper to have the same loss. No, the best array is simply to wire them all in series up to 13 or 14 panels and operate the entire string at only 7 to 8 Amps using #12 wire and a single central inverter. Also this ELIMINATES the totally irresponsible RFI emissions from having dozens of high power siwitching microinverters all over your roof generating RF emissions totally destroying the weak signal potential of radio communications in the area of your house. The ONLY time microinverters have any value is when you cannot arrange at least 10 panels all facing the same way and generally in clear sun. But if you have shade, then use a chai saw, not microinverters to solve the problem. There is one other place where microinverters can bebnefit, and that is when your large series string array becomes more than half shaded. At that point, then yes, the central inverter may just drop out due to low voltage. But again, the evening shade only lasts a half h our or so and the suna angle is so poor that hardly any power is lost, and/or, if you have that much shade, then you have a poor solar design and again, need a chain saw, not more expense of microinverters. Microiinvertesa may have made sense when they cost $200 and solar panels cost $1200 each in 2008, but now when solar panels cost under $200 and even less than a microinverter, the microinverteres make no sense generally. RANT off. Bob, WB4APR Another is that high temperature reduces the efficiency of cells. (One way is to put the entire system on top of water, which will limit how hot it gets) On Sun, Jun 5, 2016 at 7:29 PM, Larry Gales via EV <ev@lists.evdl.org> wrote: > 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? > > Thanks, > > -- > Larry Gales > -------------- next part -------------- An HTML attachment was > scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20160605/ac5 > 420ed/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... 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