Solar panels

[Boomer]

I have some questions regarding 12v solar panels. First how are they used? Do they just charge the batteries or are they used for lights and appliances? Where are they wired in? Living in California we get sun most of the year and I was considering using them when the unit is parked to keep the batteries charged. Is anyone doing this or using these panels?

 

[gary.l]

My wife and I have been using them for at least 15 years. We got one when we had our Aliner when our camping was at state and national forest campgrounds with no hook-ups and run on battery power only. One night when it got cold we ran the furnace all night and when we got up in the morning the battery was down to 8 volts. It was a sunny morning and the battery was back up to full charge by 11 am. That was with a 15 watt panel. The panels now are up to 160 watts and you can even run small appliances off them with a big enough battery supply and an inverter. They will work on cloudy days but take longer to work. They say they will even work under 1 inch of snow. We plan on getting a new one for our reflection as when we go out west this year some of our camping will be dry.

We asked them at the factory during our tour and they told us that if we had them installed on the roof it would void our roof warranty. We have a frame for it and have it wired with a long 12 gauge wire and can stretch it out to the sunlight.

Here is a useful link and a good site with both info and supplies http://www.solarblvd.com/

 

[Jeff K]

Hi Boomer,

I don't know anything about solar, but very interested in what others have to say. I'm just excited to see another Grand Design owner from California. We are near Sacramento. So far, we haven't seen another GD on the road, how about you? Enjoy the trailer!

 

[Boomer]

We are down near Turlock and went all the way to Nipomo (great dealer and service) to pick it up and on the way home we saw a Solitude going south on 101.
I don't plan on drilling any holes anywhere, I want to buy or build something portable.

 

[Sandi]

I am a fan of solar chargers especially the battery tender units. Having said that I want to offer one word of advice. I bought the 10 watt unit for our TT for the same purpose you are speaking of. I attached the unit by the two upper corner mounting holes. I used wire ties through the holes and attached them to the propane cover tie downs. After a few windy weeks the corners got loose and allowed the panel to fly up and fracture on the tongue jack handle. The unit was great just be aware the corners are not adhered to the panel. They are just friction fit in place.

 

[Timon0x31]

I've been researching solar, again the engineer in me, for a long time for homes but now I'm looking at the issues for RVs and do fine that they present unique challenges. One thing I've come to the conclusion about however is it that you really should not mix your house 12V battery with your solar system used to produce AC power. There are many reasons for this.

• First if you run your solar batteries down and they are also your house batteries then you totally out of power. If they are separate then you've only lost your AC power.
• Inverters run much more efficiently on higher battery voltage. A 48V input inverter is more efficient than a 12V one. If you can run at 72V that's even better but at 72V you need to shield the connections as it's considered hazardous by UL. For most a 48V system is best.
• Running the panels at higher voltage prior to the chargers is again much more efficient. Since the panels are already rated to 600V as are the cables running from the panels to the charger it's quite safe. In addition since you're running at a higher voltage the wire gauge is smaller as are the losses. This does require running 6 or 7 panels in series. If you want more power then you have to double that. BTW, this can also be done with a 12V system.
• You can leave your house battery charger in place. True this is not as efficient as charging directly from the panel but it makes the entire system much simpler and more redundant. If you really want to charge the house batters directly from solar then use a single solar panel and charger just for the house battery. That panel would be separate from the AC system.

Currently I'm working the numbers to see just how much solar one needs to get by and if you can power one air conditioner during part of the day incase you happen to be in a really hot area.

Still the biggest issue right now with solar is which panels and how the heck to mount them for best efficiency.

Sometime in the future I'll post a diagram on this. Hopefully by the time we get our rig I'll have this worked out.