Flouw Posted June 30, 2023 Share Posted June 30, 2023 Hi All. some opinion/advise needed. PV capability of the OG3.24 inverter is as follow. MAX power 1500w VOC 145V MPPT Range: 30VDC - 115VDC Max Solar Curret 60A the panels i currently have, and what i will be adding more of (STC Spec) Power 560w VOC 50.47 Max Power current 13.41 ISC 14.15 (NOCT) Power 421w VOC 39.25V Max Power current 11.42 ISC 11.42 so, i have been running one of these panels on my smaller Mecer (600w) to monitor the PV array. the panel has been "mobile". moving it around, aimed at the sun nicely. and the most power i was able to get was 420w. taking in consideration, the PV voltage is then sitting at 29.5v. panels mounted, during the winter in Gauteng will obviously not give as much as what ive been able to get from it now. but in the Summer that will definitely change. my question... im mounting the new inverter this weekend, two panels i will obviously put them in Series, as it just makes more sense. now that is where im stuck, i cant string 3, as that will exceed the VOC. if i would like to go 3 panels to get slightly over the 1500w mark. do i connect them 3 in parrelel? OR can i go 4 panels, 2s2p, not to exceed the VOC, according to me the max power current will also be below the max of the inverter. i would appreciate any and all advice and input. PS, my roof is a 23 deg slope. tile roof. im considering making the frame with adjustable support legs at the back to angle the panels better for winter. summer it should be OK - I think Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted June 30, 2023 Share Posted June 30, 2023 (edited) The 60A from solar would be the charge current to the batteries. Working from the 1500w PV give about 17A from panels if 2 in series at about 90V is used. Yes 2 in series is fine but using 2S2P you adding 2240W on a 1500W MPPT. Edited June 30, 2023 by Scorp007 Quote Link to comment Share on other sites More sharing options...
Flouw Posted June 30, 2023 Author Share Posted June 30, 2023 (edited) 33 minutes ago, Scorp007 said: The 60A from solar would be the charge current to the batteries. Working from the 1500w PV give about 17A from panels if 2 in series at about 90V is used. Yes 2 in series is fine but using 2S2P you adding 2240W on a 1500W MPPT. and using 3 panels? will that have to be 3p? EDIT: for argument sake, what is more efficient? 4 x 500w panels in series? 4 x 500w panels in parallel? 4 x 500w panels in 2s2p? this information im unable to find anywhere Edited June 30, 2023 by Flouw adding more information Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted June 30, 2023 Share Posted June 30, 2023 26 minutes ago, Flouw said: and using 3 panels? will that have to be 3p? EDIT: for argument sake, what is more efficient? 4 x 500w panels in series? 4 x 500w panels in parallel? 4 x 500w panels in 2s2p? this information im unable to find anywhere Normally one would not want to over panel the inverter MPPT. 3 is a now go as it will far exceeded the Voc of 145V on a cold day. Try to not go higher than 130V on the panels in series. Even 4x500W is too high to my liking. I would stick to about up to 1800W which will be quite a bit lower at NOCT which is fine if you use NOCT of below 1500W. On these smaller inverters it is a lot of times easier to get to close to max by using 355+W panels than the highest rating you can get. Using 330W should get you to 3S but it does not help if you try to get to 1500W. Quote Link to comment Share on other sites More sharing options...
Flouw Posted June 30, 2023 Author Share Posted June 30, 2023 3 minutes ago, Scorp007 said: Normally one would not want to over panel the inverter MPPT. 3 is a now go as it will far exceeded the Voc of 145V on a cold day. Try to not go higher than 130V on the panels in series. Even 4x500W is too high to my liking. I would stick to about up to 1800W which will be quite a bit lower at NOCT which is fine if you use NOCT of below 1500W. On these smaller inverters it is a lot of times easier to get to close to max by using 355+W panels than the highest rating you can get. Using 330W should get you to 3S but it does not help if you try to get to 1500W. @Scorp007 so if i have to use 3 panels. 560w max rating per panel, that will add up to 1680w. use all 3 in parallel. that will have VOC at 50v. which will be within the working voltage of the mppt. will 3p be as efficient as 2s? Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted June 30, 2023 Share Posted June 30, 2023 4 minutes ago, Flouw said: @Scorp007 so if i have to use 3 panels. 560w max rating per panel, that will add up to 1680w. use all 3 in parallel. that will have VOC at 50v. which will be within the working voltage of the mppt. will 3p be as efficient as 2s? Ignore efficiency for such small strings. Using 3x560W in series can cause the Voc to reach 160V on cold days and your MPPT goes up in smoke. Not worth it. 3S2P of 275W or up to 330W could work but you have to caution against the Voc and will be panel specific. Most 60 cell panels could be the better group of panels to look at. Quote Link to comment Share on other sites More sharing options...
Flouw Posted June 30, 2023 Author Share Posted June 30, 2023 3 minutes ago, Scorp007 said: Ignore efficiency for such small strings. Using 3x560W in series can cause the Voc to reach 160V on cold days and your MPPT goes up in smoke. Not worth it. 3S2P of 275W or up to 330W could work but you have to caution against the Voc and will be panel specific. Most 60 cell panels could be the better group of panels to look at. i think i have asked on all 3 of my above posts. why cant i use 3 x 560w panels in PARALLEL. Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted June 30, 2023 Share Posted June 30, 2023 24 minutes ago, Flouw said: i think i have asked on all 3 of my above posts. why cant i use 3 x 560w panels in PARALLEL. The maximum current to the MPPT is not specified and I will not take a guess. I did calculate it using 2 panels in series at 90V. Those 3 panels in parallel could potentially provide over 45A and will leave a clear answer on that for other members with the experience. I will never push these inverters to their maximum. Just as no car is made to run at maximum speed and revs 24/7. Noem my maar bang Jan Quote Link to comment Share on other sites More sharing options...
GreenFields Posted June 30, 2023 Share Posted June 30, 2023 34 minutes ago, Flouw said: i think i have asked on all 3 of my above posts. why cant i use 3 x 560w panels in PARALLEL. Just try it out. You won't be exceeding the maximum solar charge current of 60A. Your biggest risk is going below the operating Voltage range, and losing efficiency/operation in lower sunlight conditions. You didn't explicitly state the Vmp spec of the panel, but you did indicate that you were producing the most power at 29V, which is just outside the 30-115VDC range. Quote Link to comment Share on other sites More sharing options...
Flouw Posted June 30, 2023 Author Share Posted June 30, 2023 Attached a data sheet from the panels. Aswell as from the inverter. @Scorp007 the calculations you did at 90v seems to be correct for 2 panels. However. If i install 3 panels on 3p. They wont be running that high voltage. So the maths are rather different. My thinking. And perhaps im wrong. 2s will have the voktage range much higher in the working range. And on bad/cloudy weather there will me alot more room for the inverter to operate and get enough amps out. As with running 3p. The voltage will be towards the lower working range. And will dip below the working range when its cloudy. Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted June 30, 2023 Share Posted June 30, 2023 1 hour ago, Flouw said: Attached a data sheet from the panels. Aswell as from the inverter. @Scorp007 the calculations you did at 90v seems to be correct for 2 panels. However. If i install 3 panels on 3p. They wont be running that high voltage. So the maths are rather different. My thinking. And perhaps im wrong. 2s will have the voktage range much higher in the working range. And on bad/cloudy weather there will me alot more room for the inverter to operate and get enough amps out. As with running 3p. The voltage will be towards the lower working range. And will dip below the working range when its cloudy. Thanks for more PV specs. Still not sure if the MPPT can handle 45A from the panels if you use 3P x 560W as it it not indicated. Quote Link to comment Share on other sites More sharing options...
Flouw Posted June 30, 2023 Author Share Posted June 30, 2023 24 minutes ago, Scorp007 said: Thanks for more PV specs. Still not sure if the MPPT can handle 45A from the panels if you use 3P x 560W as it it not indicated. Inverter states 60amp max solar. Quote Link to comment Share on other sites More sharing options...
Flouw Posted June 30, 2023 Author Share Posted June 30, 2023 For experimental purposes. Im connecting 2 in series tomorow. Will monitor it for 3 days. Then connect in parallel. And monitor for 3 day. If the weather plays along. And i can report back findings on micro scale. Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted June 30, 2023 Share Posted June 30, 2023 (edited) 47 minutes ago, Flouw said: Inverter states 60amp max solar. That 60A is for charging and is at 24V not from the panels which at higher volts like 50V could be a lot lower. That's how I see it. The same with the AC charging is not 60A at 230V but at battery voltage. Edited June 30, 2023 by Scorp007 Quote Link to comment Share on other sites More sharing options...
TaliaB Posted June 30, 2023 Share Posted June 30, 2023 (edited) 56 minutes ago, Scorp007 said: That 60A is for charging and is at 24V not from the panels which at higher volts like 50V could be a lot lower. That's how I see it. The same with the AC charging is not 60A at 230V but at battery voltage. @Scorp007You are 100% correct in your above statement pictures attached to show this on a 12v system using Epever Mppt and 2x330w panels in series, charging 12v 300ah Lfp. This was @09h30 Edited June 30, 2023 by TaliaB Quote Link to comment Share on other sites More sharing options...
Coulomb Posted July 1, 2023 Share Posted July 1, 2023 3 panels in parallel should be fine as it is a nominally 24 V system. The total panel power of 1680 W is 112% of rated (25 V x 60 A = 1500 W). So that should be fine. Scorp007 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.