Ethan Posted April 10 Share Posted April 10 (edited) Hi Guys, I'm new to the forum and the solar DIY thing. Recently, I add a small PV array to my Axpert invert in order to prolong the battery running time during the extreme power outage, i.e. stage 6 load shedding in day time. PV setup as following: 5 panels in series total 500w max Vmp 85v max Imp 6A The system is working fine but there is an interest finding when I had time to look at the perform carefully. My invert is reporting a set of mismatching figures. for example, when PV voltage is 76.8v, current is 6A, the total PV input watt is only 340w. I know the Amp value is reported as integer (with a potential round up/down), but even though, use 5A to calculate a conservative value, my PV input watt is expected at 384w or above. Anyone has a clue of what is happening here? BR, Ethan PS: I use power watch app to display PV voltage and watt, Amp reading is from the inverter, so that all three figures could be showing in the same photo. Edited April 10 by Ethan Quote Link to comment Share on other sites More sharing options...
Vaal Posted April 10 Share Posted April 10 (edited) 5 panels in series. At what is the panels Voc per panel and I max? What length and size is your pv cable? Do you have access to a multimeter to test the pv V? What is the max pv input V of your inverter? Edited April 10 by Vaal Quote Link to comment Share on other sites More sharing options...
Ethan Posted April 11 Author Share Posted April 11 Hi Vaal, I use 6mm2 cables throughout, +/-15m length between PV and inverter. I think you are right, I could identify the "over counted" figure/s by measuring each panel individually. Thanks for the advice, I will make the measure once I returned, just left for a trip. For now, I'm more interesting to find out whether other people also seeing the same inverter behaviour, or just only me. ------------------- Quote Link to comment Share on other sites More sharing options...
Ethan Posted April 11 Author Share Posted April 11 PS: I do admit that producing 340w from a 500w array isn't the optimal setup. This is due to the limited space in my backyard to play around the directions and angles, after all, it is a temporary setup anyway. Therefore, my purpose to initial this thread is not try to optimise my PV setup but other to understand my inverter better. Quote Link to comment Share on other sites More sharing options...
Calvin Posted April 11 Share Posted April 11 I believe that the PV input current reported is the current from the SCC to the main board, which is at (approx.) battery voltage. So, the 6A is approx. 300W. Coulomb 1 Quote Link to comment Share on other sites More sharing options...
Ethan Posted April 22 Author Share Posted April 22 (edited) Finally, got chance to do the measurement after a hectic week. In a nutshell, the Voltage & Amp from PVs align with the value reported by the Inverter. The question is around the value of "PV input power". I felt this value seems to be an "usable PV input power" as it fits the equation of "grid+pv = battery + consumption" perfectly. In other words, MPPT received ± 420w from PV but only feed ±350w to the bus bar. Is this ratio (350/420) reasonable? watt meter measurement Energy flow Edited April 22 by Ethan Quote Link to comment Share on other sites More sharing options...
Coulomb Posted April 25 Share Posted April 25 In your first post, I note that the PV current is 6 A, which lines up with your PV power: 56.7 V (battery) * 6 A = 340 W. So many people assume that PV current is the panel current; like most battery chargers, it's the current at the output of the charger, not the input (panel) current. Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted April 25 Share Posted April 25 On 2024/04/11 at 3:25 PM, Ethan said: PS: I do admit that producing 340w from a 500w array isn't the optimal setup. Don't be so harsh on your system. Although 2 days have full sunshine the production can vary. Take for instance yesterday the irradiance was much lower in Gauteng than normal days. This is on a north facing 1300W string. Quote Link to comment Share on other sites More sharing options...
Antonio de Sa Posted April 25 Share Posted April 25 26 minutes ago, Scorp007 said: Don't be so harsh on your system. Although 2 days have full sunshine the production can vary. Take for instance yesterday the irradiance was much lower in Gauteng than normal days. This is on a north facing 1300W string. @Scorp007 as you said, yesterday nice sunny day but sun eradiation a bit on the low side. I usually get my system to produce about 4.3 KW at midday. Yesterday max at 3.57. Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted April 25 Share Posted April 25 40 minutes ago, Antonio de Sa said: @Scorp007 as you said, yesterday nice sunny day but sun eradiation a bit on the low side. I usually get my system to produce about 4.3 KW at midday. Yesterday max at 3.57. What is interesting is on the bad day like yesterday there is less of a drop after 12h00 when I get some shade from the apex of a roof. This string is nearly flat on a car port. Quote Link to comment Share on other sites More sharing options...
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