can you have too much solar?

atlasb · September 2020

Just wondering at what point is too much solar capacity. You can only recharge/ charge your batttery so fast and with so much current/ volts so at what point is enough capacity enough? Your charge controller limits the voltage charge if I understand its function so if your generate more than needed what happens?

ChrisFix · September 2020

Solar charging capacity and battery storage should be sized to 'match' each other...so yes, you can have more solar capacity than battery storage to send it to, but how much is too much depends greatly on your individual use case.
If you generate more energy than you have battery storage for it to go to, nothing happens except the lost opportunity to store more energy. It's like your house wiring...you probably have 200 amp service coming into your house, but at any given time only utilize a fraction of that.

4ncar · September 2020

The only thing I can think to add is, with a larger solar array, you are able to collect more energy on cloudy days, then you would with a smaller array, meaning that you might be able to charge your battery(íes) on a cloudy day vs not...

Sharon_is_SAM · September 2020

A PWM controller can not limit the current output. They just pass the panel current through to the batteries. So, an over-sized panel output or undersized controller can damage the controller. So, the PWM charge controller should be rated for the maximum combined panel output plus a safety margin of about 25%.

And here is a quote from Renogy re the MPPT controller:

“MPPT charge controllers limit their current output, so technically you can make the solar array as large as you want and the charge controller will limit the output current to the maximum allowable. There is a practical limit though, if the solar array is too large then the power is just wasted, since the charge controller is always limiting the output.“ As Chris said - power is wasted.

MarkAl · September 2020

I agree w/ ChrisFix about matching your charging w/ storage. But (always one of these) w/ solar, camp surroundings and weather require other alternatives. Do you go w/ generator or more panels to capture some energy from less light as 4ncar said. Probably a generator makes the most sense as our trailers / TV don't have a lot of extra space and I have better things to do than re-position panels to avoid shadows or put in the best position. That said I added 2 additional panels but I'm pretty sure the 15 watts (10 Amp*Hrs) during the day I may pick up is too low to justify setting up the panels. Though I haven't given up the fight, I just dislike the thought of running a generator. For me it's more of an engineering challenge. Though the reality of 1 week of heavy overcast in the woods ... refrigerator is going off. But I may have moved on by then.

ADRawli · September 2020

I’d say this guy was probably testing your premise...

... but to be fair, its also an electric drive vehicle, so maybe more cool than funny.

4ncar · September 2020

@MarkAl 1 week, no sun!😳 that’s when I point the panel towards the fire, and hope for the best! Lol

GatorEgg · September 2020

Not trailer but related. I had solar on our sailboat. 600 watts with 1000 amp hours of batteries. But I had modified my water heater to eliminate the power waste. I redirected the excess power from the solar controller heat sink to our boats water heater. The water heatEr was originally either 120 ac or heated by engine hot water. I exchanged one of the heating elements for a dc element. So if I had excess solar power it heated my hot water. Needless to say cruising the Caribbean we had abundant sun and always hot water.

can you have too much solar?

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