I am new to solar. I have an IEE P2400 portable power station which has a solar voltage input range of 12-60V, and 500 W, and a maximum charging current of 10 amps. When I connect two 400 W solar panels (18V/22 amps each) in series, the station charges, showing about about 360 W. But when I add a 200W panel (18V/11 amp) to the series, the station shows 0 W charging. I assume the unit is protecting itself, but I don't know why, since the total voltage (18 V x 3 panels = 54 V) is within the station's 60 V limit. Perhaps the three panels are delivering slightly more than 500 W, but I didn't think that would cause the station to not accept any current from the panels...or would it? When we kept the two 400 W panels in series, and added the 200W panel in parallel, rhe station also stopped charging. Thank you for your help!
Portable Power Station Charges with 2 Solar Panels, But Not With 3, Within Voltage Limit
- Thread starter BKH
- Start date
azazel1024
Solar Enthusiast
What is the actual maximum short circuit voltage of the panels? Most 18v panels are actually 18-22v for maximum power voltage (Vp), but even higher maximum short circuit voltage.
Generally, that maximum short circuit voltage is going to be 3-5v higher than the maximum power voltage. Even without knowing true Voltages here, I am positive that yes, that is what is happening, is the panel voltages are too high and the MPPT is shutting down.
Not sure on the two 400w in series and adding a 200w in parallel. What should happen is that the input voltage is going to get limited to the 200w panel's voltage. You don't want to mix series and parallel panels of differing total voltage. The maximum voltage of the input is going to be limited to the voltage of the lowest voltage panel/string.
Thank you very much for the fast reply. The open circuit voltage for the panels is 21.6V. I couldn’t find the maximum short circuit voltage, but if the voc is applicable, for the three panels in series, that would add up to 64.8V--greater than the 60V solar input limit.
Because the power station has a max charging current of 10 amps, does that mean that it will throttle the solar charging amps down to 10 amps? If so, putting panels in parallel will reduce the number of charging watts, since in parallel, the volts would only be 18 V ( or perhaps 21.6), but the amps which would theoretically be added in parallel, will be limited to 10 amps, correct?
azazel1024
Solar Enthusiast
Yes and yes. The Voc is the short circuit voltage. Many MPPTs can take in a little over their rated, but usually it is 2-3v over (and also not recommended).
Yes, no matter the voltage, the maximum amps it'll draw is 10. So, if you put them all in parallel, 10 amps is all you'll get, probably at 21.6v (since the MPPT is still going to find the maximum power point, and if being clipped at 10 amps, it'll seek maximum volts.
Your best bet would probably be to grab another 200w panel that matches the other one and put them in 2S+2P configuration. That way you are over paneling in a way that the MPPT can use.
That said, with a maximum of 500w, you'd need 50v, and that is going to be extremely hard to achieve with most realistic panels/combinations and also stay under the 60v maximum of the MPPT. At least with a 10amp max. You are realistically going to be facing more like 400 some watts with those panels, or with most configurations of panels.
Yes, no matter the voltage, the maximum amps it'll draw is 10. So, if you put them all in parallel, 10 amps is all you'll get, probably at 21.6v (since the MPPT is still going to find the maximum power point, and if being clipped at 10 amps, it'll seek maximum volts.
Your best bet would probably be to grab another 200w panel that matches the other one and put them in 2S+2P configuration. That way you are over paneling in a way that the MPPT can use.
That said, with a maximum of 500w, you'd need 50v, and that is going to be extremely hard to achieve with most realistic panels/combinations and also stay under the 60v maximum of the MPPT. At least with a 10amp max. You are realistically going to be facing more like 400 some watts with those panels, or with most configurations of panels.
Please correct me if I'm wrong, but because all of the panels are 18V (maybe up to 21.6V), both series of two panels would generate up to 36- 43.2V, which would be the max voltage in parallel. Then if the power station throttles down the amps to 10 despite receiving more in parallell, the max number of watts the unit will accept is 36- 43.2V x 10 amps = 360 - 432 W in a 2S+2P configuration, which is the same as if I have the two 400W panels in series by themselves? Thank you again for helping with this!
azazel1024
Solar Enthusiast
Thank you again for your help!
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