Has anyone experimented with high-voltage solar panels on their RV? I'm thinking along the lines of the 250-300+ watt panels that output 40-60 volts, versus the little 25-100 watt 12 volt panels typically used in RV systems?Residential and commercial demand has really lowered the price of these big panels, there are many choices for under $1/watt compared to $2 to $3 per watt for the small panels.I can see several downsides, like dangerous high-voltage DC current, and the need for an MPPT type charge controller versus the inexpensive linear / pwm units used on 12v panels.But the flip side, two 250 watt panels versus five 100 watt panels - less glass to clean, less wiring to maintain and... fewer holes in the roof.

Lots of people running high voltage panels with MPPT controllers. Not unusual at all. I not currently but my next RV setup will likely be that setup

Gads nothing that low. 675w, about 90 volts on mine.Forum Members Solar Installations With Pics

One regular poster on this forum (Jim - HiTech) even suggested that if the cost of an MPPT controller is too high for you right now, maybe use one or two of the higher voltage panels with a PWM controller to start with. If you need more solar power, you can just upgrade to MPPT controller and harvest more of the power generated by the panel(s).The economic reasoning is that a 250W 24V panel costs not too much more than a 140W 12V panel. So why not "pre-pay" for part of your next solar upgrade with a small incremental up-front cost. Plus the 24V panel will deliver more power early and late in the day when the sun is low.Plus the cost of MPPT controllers will likely drop in the future.Ed

high voltage solar panels? | Good Sam Community

65 Replies

mena661
Explorer
Oct 06, 2013
RVUSA wrote:

I do try and not stub my toe in the dark. :B
LOL! Thanks all, great thread.
bdosborn
Explorer
Oct 06, 2013
2oldman wrote:
I'm not concerned about a few percent of efficiency.

Amen to that! Chasing the rabbit down the hole makes my head hurt. :B Besides, I still haven't figured out what keeps the electricity from spilling out of the wall into a puddle on the floor. :h

Bruce
KJINTF
Explorer
Oct 06, 2013
Agreed slap another flat mounted panel up top and call it good

Have to disagree with the previous posted efficiency graphs - from my real world experience I see <2% conversion loss from my 40Volt array to the 12 Volt battery bank

I posted several graphs a while back - overall MPPT conversion effiecieny was in the very high 90's all the time from low current demand to high current demands
CA_Traveler
Explorer III
Oct 06, 2013
Losses from wiring, controller, shadows and non tracking panels for a RV lead to consideration of another panel. Especially in these days of lower panel prices.
2oldman
Explorer II
Oct 06, 2013
bdosborn wrote:
Yeah, but don't you need a converter to run typical RV 12V loads? That eats up any efficiency gains.
Yes, I have a small DC-DC converter. What's kinda cool about that is that the voltage never varies from 12.5-12.6 v.

I'm not concerned about a few percent of efficiency. Just adding another perspective.
bdosborn
Explorer
Oct 06, 2013
2oldman wrote:
bdosborn wrote:
Add on the efficiency losses incurred by transforming from a high voltage to 12V battery voltage and it seems self defeating to run high voltage panels.
It can be.. that's why it's better to have a 24v or higher BB.

Yeah, but don't you need a converter to run typical RV 12V loads? That eats up any efficiency gains.

Bruce
2oldman
Explorer II
Oct 06, 2013
bdosborn wrote:
Add on the efficiency losses incurred by transforming from a high voltage to 12V battery voltage and it seems self defeating to run high voltage panels.
It can be.. that's why it's better to have a 24v or higher BB.
bdosborn
Explorer
Oct 06, 2013
wintersun wrote:
There is a reduction in current loss with higher voltages but for the runs involved in a RV this is not a factor of any significance once you get up to 34 volts. I optimized my setup to have a total current loss of under 3% but afterwards realized how silly it was to have done so.

Add on the efficiency losses incurred by transforming from a high voltage to 12V battery voltage and it seems self defeating to run high voltage panels.

You may drop your copper losses by a percent or two but overall MPPT efficiency is down by as much as 6% for this controller.

Bruce
RVUSA
Explorer
Oct 06, 2013
mena661 wrote:
GordonThree wrote:
Lots and lots of things to be afraid of out there.
Xforever, I don't worry myself over such things honestly. I just make sure I'm not careless.

I do try and not stub my toe in the dark. :B
mena661
Explorer
Oct 06, 2013
GordonThree wrote:
Lots and lots of things to be afraid of out there.
Xforever, I don't worry myself over such things honestly. I just make sure I'm not careless.

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high voltage solar panels?

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