solar panels ( 4) 250 watt panels in series/parallel
- Thread starter sparkyv
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sunshine_eggo
Happy Breffast!
No. There's only a problem if you're testing them at high noon with the sun directly overhead during the time of year you get the most and intense sunshine.
It was under stc. 25 degrees f. Amps should be 16. 2 series strings in parallel. 30voc 8sc each
sunshine_eggo
Happy Breffast!
So you tested the panels with a known 1000W/m^2 hitting them? How did you measure that?
Bud Martin
Solar Wizard
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Are you sure the Voc is only 30V?
Vmp * Imp = panel Wattage.
Full spec of the panel?
Make and model of the SCC?
Batteries type?
Vmp * Imp = panel Wattage.
Full spec of the panel?
Make and model of the SCC?
Batteries type?
Last edited:
The panels are 4 trina 250 watt. I am getting the 60vdc. But only 3 to 4amps. Measured by a victron 150 /35. Charge controller. 2 series strings in parallel.
Battery is a 12v 200ah
The Trina 250W panels (TSM-250PA05) have a Vmp of 30.3V, Imp of 8.27A, Voc of 37.6V, and Isc of 8.85A.
Your panels are in 2S2P (FYI - that's the clearer notation).
sunshine_eggo
Happy Breffast!
sunshine_eggo
Happy Breffast!
No. Refer back to my original post. You only get max output when you have 1000W/m^2 of irradiance on the panel. That happens when it's peak solar season, high noon, etc.
Yes, you'll get a boost from lower panel temp, but that depends on the panel temp, not ambient. Panels warm in the sun, so they're always warmer than ambient.
A 1000W array should be giving you between 0W and 1000W at midday depending on the arrangement (series/parallel), the angle they are mounted, the direction they face, any shading, sky conditions, and temperature. And it also depends on the battery SOC. If the battery is nearly full you'll get very little out the panels no matter what the conditions.
STC is at 25ºC (77ºF), not 25ºF.
sunshine_eggo
Happy Breffast!
It depends completely on conditions.
If you provide details like:
Geographic location (to determine solar and weather effects)
Panel tilt (degrees from horizontal)
Panel orientation (does it face south)
Shading implications
Battery state of charge (a battery that is near full won't take any more power than it needs to hold voltage)
If you provide details like:
Geographic location (to determine solar and weather effects)
Panel tilt (degrees from horizontal)
Panel orientation (does it face south)
Shading implications
Battery state of charge (a battery that is near full won't take any more power than it needs to hold voltage)
sunshine_eggo
Happy Breffast!
It depends on where the state of charge info is being derived. If it's the % on the charge controller, it is almost certainly incorrect as those are typically voltage based, and they mean nothing.
The battery determines it, not a SoC measurement. The battery NEEDS X amps to hold it at the absorption voltage.
If you understand it, then you're the best judge as to whether 3-4A is what you should be getting or not.
3-4A may be completely normal for the conditions/array facing. Without divulging that extra info to us, we can only guess.
As an example, my 3000W array was only putting out 506W today when it was putting out 2550W yesterday. The difference was:
1) less solar today.
2) Yesterday would have been higher, but it was limited by being in absorption mode.
506W today was normal.
I obviously should not use the term STC loosely. I was simply trying to make understood the conditions were very good, i.e. full sun, good angle, low temp. lower temp being better than stc.
sunshine_eggo
Happy Breffast!
One way to eliminate the potential restriction of a battery in absorption mode is to deliberately apply loads > your array power.
Consider repeating the test at high noon under the best solar conditions possible and draw >1000W from the system.
Consider repeating the test at high noon under the best solar conditions possible and draw >1000W from the system.
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