July 28, 2025Jul 28 I currently have 2 strings of 5 (550w artsolar panels). I'm planning on adding 2 more panels (one each per string) Artsolar changed their specs on the latest 550w panel so the new one is different.
July 28, 2025Jul 28 2 hours ago, Jeppe said:Artsolar changed their specs on the latest 550w panel so the new one is different.If the total Voltage for the string is still within specs of you MPPT/Charge controller, then it should be fine, the current on the new panels might restrict the power a little bit, but its probably ignorable... 13.18A STC vs 13.1A STC, the voltage is higher, though, 39.8V vs 42V, but I'd imagine you hardly ever, if ever, see the 13.18A MP, so I doubt you'd notice this... I am assuming your existing 2 strings are series strings and thus they potentially have 47.1V * 5 as ocV, which is 235.5V, with another new panel added in series you have an ocV of 285.35V or so, as long as this is still within specs, you'd be good to go...
July 28, 2025Jul 28 I agree with Kalahari Meerkat. Your Maximum power will be limited by your worst performing panel in the series arrangement, in this case the 13.1A panel. You likely will never such current (you probably already know based on past performance how much current your PV array outputs). It should be fine. Typically currents must be matched in series arrangements, voltages are matched in parallel.
July 28, 2025Jul 28 6 hours ago, Denns said:I agree with Kalahari Meerkat. Your Maximum power will be limited by your worst performing panel in the series arrangement, in this case the 13.1A panel. You likely will never such current (you probably already know based on past performance how much current your PV array outputs). It should be fine. Typically currents must be matched in series arrangements, voltages are matched in parallel.Considering this, would it be better to slightly over spec an additional panel, assuming the total remains within the inverter specs, if you cant find exact matches?
July 28, 2025Jul 28 I guess you could but looking at the specs you will lose out on 39.8V*0.08A = 3.184W. (Since the existing array will operate at 13.1A rather than 13.18A. Over 10 existing panels that is a loss of 31.84W. This is very inconsequential in my opinion.
July 29, 2025Jul 29 15 hours ago, Kalahari Meerkat said:If the total Voltage for the string is still within specs of you MPPT/Charge controller, then it should be fine, the current on the new panels might restrict the power a little bit, but its probably ignorable... 13.18A STC vs 13.1A STC, the voltage is higher, though, 39.8V vs 42V, but I'd imagine you hardly ever, if ever, see the 13.18A MP, so I doubt you'd notice this... I am assuming your existing 2 strings are series strings and thus they potentially have 47.1V * 5 as ocV, which is 235.5V, with another new panel added in series you have an ocV of 285.35V or so, as long as this is still within specs, you'd be good to go...This right here.I had the same question a while back, my panels specs were a little further apart than yours ( it was 500w panels and I added 2 595w panels) so my setup is 4 x 500w and 2 x 595w all connected in series, and the mppt behaves exactly like Meerkat said.
July 29, 2025Jul 29 I'd still be cautious, more curious actually. The current seems to diverge more at the lower irradiation of NOCT and maybe you are more likely to spend more time in the lower ranges.If you have an inverter that clips MPPT current at 13A the difference at STC is moot anyway.Can you post a link to the full spec sheets including the Current/Voltage graphs? Edited July 29, 2025Jul 29 by GreenFields
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