Dual inverter setup with 2 battery banks 12v system

[luvrbus]

I never saw the sunshine on the Oregon coast 1 winter when we were there lol

[Oregonconversion]

 So I have decided to put 400 W of solar power on my two battery Banks.  Even in Oregon weather that should keep them charged. 

[Iceni John]

So I have decided to put 400 W of solar power on my two battery Banks.  Even in Oregon weather that should keep them charged. 

Er, no, it won't!   Not even close!   At best, that amount of PV will just about be a trickle-charge to prevent the batteries from self-depleting  -  FLA batteries by themselves (i.e. with no loads at all) lose about 5% a month.   Anything less than a 5% charge rate is essentially useless, and that's assuming you have consistent strong sunshine for many hours a day, something that Oregon in winter is not known for.   To give you some idea what I'm talking about, I have eight big grid-tie 255W panels on my bus, and they can charge my eventual eight golfcart batteries at about the maximum 13% charge rate.   The reason I have a lot of PV for less than 1000aH battery bank is simply because bus roofs often are not oriented ideally compared to a house's, so their solar production will always be less than a stationery installation where panel placement can be optimized for maximum harvest.   And my panels can be tilted to face the sun  -  most mobile installations cannot do so, reducing their output even further.   To effectively charge all your batteries will require well over 3kW of PV, and that many panels will occupy the entire roof of a 40-foot bus;  my eight panels occupy 22 feet of roof length.

Here's the solar radiation data for various locations in Oregon:   http://rredc.nrel.gov/solar/pubs/redbook/PDFs/OR.PDF   For your location you can see how much power you could expect to produce.   And this article explains the benefits of tilting the panels:  http://www.solarpaneltilt.com/

Good luck, John

[Oregonconversion]

 Yes John, that's what I meant. It will keep my batteries charged when they are not in use.  A wind generator where I am at ( near the coast )  would be much more sufficient for creating power though.

[Oregonconversion]

 I'm guessing on cloudy days I could get about 5 A with a 400 W set up.

[Oregonconversion]

 Is there a way to have a generator start up once a week for an hour or so to charge all of my batteries? It seems that would be a lot less costly.
Even though I got these batteries for free, doesn't mean I want them to go dead  if I'm not there for a few months.  Renogy 100 watt mono panels look great for the cost.  It's too bad that they will get most of their use during the summer, when you need them the least.  Seriously thinking  about wind generators instead. Anyone know a good one?  My property is  about 40 miles from the coast, it does get quite windy.

Maybe a combination of wind and solar should meet my needs a little better.

[Iceni John]

I'm guessing on cloudy days I could get about 5 A with a 400 W set up.

400W of solar is theoretically able to provide about 27A at the voltage needed to charge a 12V battery bank.   I say theoretically, because the nameplate rating of PV is not what it usually produces, unless you're in Alaska in the winter or experiencing an edge-of-cloud effect.   The experts at NAWS derate PV at 77% to give usable real-world output, i.e  400W of panels will really give about 300W of useful output, and that's in good sunlight.   This means that you'll get at most about 20A at 14.7V going into the batteries, or less (a lot less) if you have PWM charge controllers.   At only 10A into each battery bank, that's about a 1% charge rate.   That's called deficit charging, and unless you fully charge your batteries every day or so with a generator or shore power, you will kill them in a short time.   If it's overcast or raining (I've heard that it's sometimes like that in the Pacific Northwest in winter . . .) forget about any useful PV power output at all.

Wind power on a bus has been tried by several folk, but I've not heard of anyone having much success with it.   Jerry Campbell had one on his Crown, but I think he's not using it any more, and there was a Fishbowl conversion with a wind turbine which didn't work too well either.  The wind generator has to be quite high off the ground, at least 25 or 30 feet to get clean airflow, and obviously cannot be in the lee of any buildings or trees.   However, most small wind turbines are rated at only 400W maximum, and usually produce much less than that.   The Oregon coast in winter may be one of the few places it could maybe work  -  when I rode my bicycle down the Oregon coast some years ago I noticed all the trees growing bent the opposite way to my travel, and the winds coming off the Pacific were strong enough that I was pedaling hard downhill, and watching other cyclists freewheeling up those same hills with the wind behind them!

Please take the time to read and learn all you can about PV and other RE  -  the NAWS and Solar Panel Talk forums are a good place to start.   If the folk there say that something will or won't work, trust their advice!

John  

[Oregonconversion]

 Looks like I will have to learn more about this.  Apparently I need much larger of a solar array.  After briefly look into it I noticed that wind generators these days are you going up to 1500-1600 max watts.

[lostagain]

The simplest, least costly way to charge batteries in a motor home is a generator. They can be made very quiet too.

JC

[Oonrahnjay]

Looks like I will have to learn more about this.  ... 

     Voodoo, I tell you, voodoo! 

[OneLapper]

I have two inverters.

The main one connected to 4 T-125s, the second is connected to the start batteries. The second one lets me charge the start batteries if they need it, and keep them charged when I use the general lights or reading lights too long (when the engine is not running).

[Oregonconversion]

Interesting setup OneLaper. I think I'm going to install a gas furnace and connect my water heater to propane. Sad but true. It's what I need.