Brand New to Solar, need a bit of assistance Please

I am looking to install a system on my RV. I will be using the Epever Tracer-BN Series MPPT charge controller. I have a chance to get two, 250W used panels for $100 each. Their Open circuit Voltage is rated at 37.6, voltage at pmax is 30.3, max system voltage is 600 and fuse rating is 15A... The question is, will the Epever Tracer-BN Series MPPT charge controller work with these panels and a 12V system.

Any assistance is GREATLY appreciated!

I think you overpaid a bit for those panels, though still better than retail. Please note that Epever makes a lot of different models of controllers, all varying in the amperage and voltage they can handle. Assuming you are at 12V as you say, the math works out to be (250W X 2 panels)/13V charging = 38.5A. So, a 40A Epever controller would handle the amps. The 20A or 30A models might not.

Assuming you wire the panels in series, your max Voc is going to be 37.6Voc + 37.6Voc = 75.2V. At freezing that might go up to 75.2Voc X 1.12X =84.2V, still safely below the limits of Epever's cheaper controllers (100V max).

So, the answer is yes, it will work, assuming you select the right controller. Get the 20A Epever, and the answer changes to no.

Thanks for the information. I passed up on the deal, the panels were polycrystalline, from the research I have done, monocrystalline are better, and I figure if I buy new, I will know they haven't been abused or anything. I am looking to get a system installed on my RV as we go to the mountains and camp without hookups quite a bit.

Wendell42 said:

Thanks for the information. I passed up on the deal, the panels were polycrystalline, from the research I have done, monocrystalline are better, and I figure if I buy new, I will know they haven't been abused or anything.

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I think the discussion on the differences between mono and poly panels is a waste of time. Now I solely focus my attention on Watts/$. What I do exclusively now is shop locally on Craigslist and only buy with local pickup. Some of my very best performing panels buys were used panels pulled back off someone's house. They performed better than new panels I paid retail for. Find a seller online, then drive over to them. Bring a volt meter to test with if you have any questions about quality.

I second that, the difference between mono and poly is not that big and sometimes poly perform even better under certain circumstances. If you have a MPTT already, you can also hook it up to your 12 V battery and the panel to quickly test it before buying it.

No idea where you’re located but SanTanSolar.com often has used 250w panels for around $35 each.

Shipping is a problem cost wise for only 2 panels though

I couldn’t agree more on paying attention to cost per watt as a primary spec.

Under 20 cents/ watt is a very good price.