I am finding I need more panels above my current four. I have found I get better performance running 24v and since I only have 12v panels I have them in series. I have plenty of room for the fifth panel its the sixth one that is the problem. I have a area with my black and gray roof vents that are only 3" tall. My panels are set at 4" so it would clear the vents. Is there any problem from this? They are a T style vents so they would still get air from under the panel.

This message has been edited. Last edited by: timkelco,

It should probably work OK. I've had a panel over a vent for years and never had any issues. I'll be interested in others comments.

An Idle thought - With the panels 4" above the roof, an air gap as you will, does this cut down on solar infution of heat? Is the roof /ceiling cooler with panels above them? Anyone ever 'shot' the area with a heat gun and sent out results?

Might cut down on the A/C load.

If you do, Thanx in advance.

Going over a vent isn't a problem, it could even be seen as a plus since you'll be keeping the sun off the vent cap and protecting it from limbs.

Raising the panels has one nice advantage especially with an MPPT controller, it keeps them a bit cooler allowing more voltage to be available that boost charging watts.

As to cooling the rig I'd guess it is about a wash between a plain white roof absorbing sun and a dark panel re-radiating heat to the same roof. I didn't measure temperatures but I never noticed the roof under the panels being noticeably warmer or cooler than the rest of the roof when I was up there washing it.

And the panel being that much closer to the sun would absorb more energy......right???
Vern

It is interesting that you mention the voltage drop during the heat of the day. I have noticed my amps are steady and my volts drop the hotter it gets(95* cost me 2-3 volts yesterday). Good to know I did not mess up on my install. I think that is why I am seeing better boost out of the 24v wiring.

Looks like two more panels are going on the roof. I think I am addicted. I have been the power cop trying to use as little as possible and were on 50amps . Just trying to train the group for the real thing. Even with all that, we just use to much power. I have just enough amps to sustain us through the day and very few if any for charging before night fall. I have two generators(Onan and Honda) and do not what to use either for charging when the time comes.

Between the panels and the new batteries this is an expensive hobby. So far it is paying off. It is just going to take some time. I just have to hold off the DW from the real numbers, if she knew

quote:

Originally posted by Vern & Sue:
And the panel being that much closer to the sun would absorb more energy......right???
Vern

LOL!!!

Kinda reminds me of the old George Carlin schtick about his "Rice Crispies". I wouldn't write it all out here, but the part that made me chuckle when I read your post was:

"Have you notice that the Rice Crispies highest on the bowl dry first? It's because they're closer to the sun."

Leave it to George... he was quite the character...

Brian

quote:

Originally posted by Vern & Sue:
And the panel being that much closer to the sun would absorb more energy......right???
Vern

Yes, roughly it would be .000000000000678831323992614315194960% more power, you'd do better by shooing a gnat off the panel one day a year!

Gee You mean it won't do me any good to back my TT up on a couple of extra boards. Ha! Nice to read a little humor while dealing with techie stuff.

I know one place you can put a solar panel that will lower the temp inside the RV. If you have a skylight over the shower, or somewhere else, mount a solar panel over it to shade from direct sun. You'll still get some light but minus a lot of the heat.

Haven't done this myself, but I did block off our skylight from inside with a 1/2 inch insulation board covered in fabric to match our ceiling.

timkelco, we're adicted to solar too! It's expensive to start out, but we're going on 4 years now, the panels are still "young" and the batteries are only "middle aged". Haven't spent anything more since buying the system. They just sit up there and make power; silent, odorless, and without any effort from me

Mac

quote:

without any effort from me

Well aside from the initial learning curve where you have to absorb the limitations and minimal maintenance requirements of the system there isn't much ongoing effort. An occasional panel cleaning on a cool morning and regular battery watering is about it.

quote:

Yes, roughly it would be .000000000000678831323992614315194960% more power, you'd do better by shooing a gnat off the panel one day a year!

Stan...you need a hobby...you obviously have tooooo much time on your hands...

Regards
Gemstone

Aww come on I trimmed several thousand digits off the raw result from my computer calculator... :-)

I was actually interested in how many leading zeros I'd come up with for a 1000 foot change in altitude. Still was a lot and I'd bet atmospheric absorption would be a larger factor than distance in power production since you are looking at fractions of 93,000,000 miles. Running the numbers for a space based geosynchronous solar satellite still gives little increased power at opposite ends of its orbit.

Hmmm, Maybe I do have too much time on my hands. Don't tell Trudy, she has a list!