Panel only generates half rated watts

[Madbison]

Hello

I have a camper trailer with 220 Ah batteries, and a separate portable 110 Ah battery. I have 4 x 100 watt fold up solar panels for my away trips.

I just purchased two 250 watt solar panels with the intent to put them on the roof of my shed, and power two separate solar chargers to keep the two sets of batteries charged while at home. The two fridges on these two batteries will likely be running all year long.

So, the question is, are the solar panels i just purchase duds? Given 220 a Redarc 30 Amp solar charger, and 220 Ah battery, battery is at 70% SOC, so, solar charger will put in max amps available. I had both 250 watt solar panels propped up, ponting directly at the sun, at 12:10 pm. No clouds. 6 B&S cable to the charger (way overrated, no voltage drop). The solar charger was putiing in 6.8 amp to the battery with one 250 watt panel. I then switched to the other panel. Again, 6.8 amp. I then put both panels in with a y splitter. 13.6 Amp. The charger was recording 13.3 volt at the battery at the time, so 13.3 x 13.6 = 181 watts. That's a LONG way from the rated 500 watts with these two panels connected. And the conditions were all ideal setup.

Given a 250 watt panel, what should i expect going into the battery? About 90% of that rated wattage?

Thank you
David

 

[shavermcspud]

Is the SCC configured correctly for your battery bank?

 

[Ampster]

Given a 250 watt panel, what should i expect going into the battery? About 90% of that rated wattage?

No, 90% is optimistic. A lot depends on orientation and temperature.

 

[boondox]

No, 90% is optimistic. A lot depends on orientation and temperature.

And time of year and location.

Where are you, are the panels mounted flat? This is a bad time of year for flat panels in the northern hemisphere. The further north you are the worse it is.

To test the panels, do a short circuit test. Angle the panels for the best output. This time of year on a sunny day in the northern hemisphere you might see (at a guess) 60 to 70% of the rated output. There are calculators out there that you can use to determine what you should be getting.

 

[omanolo]

Are the panels new or used?