Posted January 7, 20232 yr Hi guys. Need a bit of help here. I have decided to upgrade from my trusty old Infini V 5k to a Deye 8.8kw Inverter with Lithium batteries. Here comes my problem. I decided to stick with my current pv panels (350w Mono Art Solar x 10). the installer said it would be fine to put them all on one MPPT in one string. Here comes the question: VOC of the panels are 47V. This would then be 470V for the ten panels. Inverter states Max pv input is 500vdc and Max MPPT voltage is 425vdc. Am I going to have a problem or should it be fine?
January 7, 20232 yr 47 minutes ago, Lionheart said: Am I going to have a problem or should it be fine? I wouldn't, I'd run 5S and depending on the current for the panels 2P, which I asume to be around 9A, so 5S2P should be ok with the Deye 8k8 inverter, I believe it has 20A for the 1st MPPT and 10A or so for the second... just check the specs for your inverter on this. I suggest keeping the Voltage well below the limits and I would suggest not to exceed 400Voc for the panel string... to ensure the magic smoke stays where it does its best work...
January 7, 20232 yr 10 minutes ago, Kalahari Meerkat said: I wouldn't, I'd run 5S and depending on the current for the panels 2P, which I asume to be around 9A, so 5S2P should be ok with the Deye 8k8 inverter, I believe it has 20A for the 1st MPPT and 10A or so for the second... just check the specs for your inverter on this. I suggest keeping the Voltage well below the limits and I would suggest not to exceed 400Voc for the panel string... to ensure the magic smoke stays where it does its best work... I have never seen specs indicating the 2nd MPPT to have a lower current than the 1st one. Part of the specs sheet.
January 7, 20232 yr Author 3 minutes ago, Scorp007 said: I have never seen specs indicating the 2nd MPPT to have a lower current than the 1st one. Part of the specs sheet. That is correct
January 7, 20232 yr 7 minutes ago, Lionheart said: That is correct The 10 panels won't exceed the 500V max for Voc even on cold days. The Vmp should also not be above 425V for the MPPTs.
January 7, 20232 yr Author 21 minutes ago, Scorp007 said: The 10 panels won't exceed the 500V max for Voc even on cold days. The Vmp should also not be above 425V for the MPPTs. Thank you. If the voltage goes over the 425V but stays under 500V what would happen? Just want to confirm what the best configuration would be with what I have.
January 7, 20232 yr The absolute safest would be 5S2P on one MPPT. I mean, you could push it closer to 500V and hope you never get any abnormal behaviour, no spikes, etc. But why even go close? I'd rather consider additional 9A panels in series on each string.
January 7, 20232 yr 15 minutes ago, GreenFields said: The absolute safest would be 5S2P on one MPPT. I mean, you could push it closer to 500V and hope you never get any abnormal behaviour, no spikes, etc. But why even go close? I'd rather consider additional 9A panels in series on each string. Why would one use 5S2P when you have a 2nd MPPT being unused?
January 7, 20232 yr 2 hours ago, Scorp007 said: Why would one use 5S2P when you have a 2nd MPPT being unused? Precisely. Put 5S onto each MPPT.
January 7, 20232 yr I have a friend with 10 panels on each string on a Sunsynk 8 kW inverter, hasn’t had an issue, he is in Cape Town where winter temperatures don’t usually dip very low. The maximum I install is 9 panels in one string ( Voc 49 volts ), just so that I don’t have problems with warranty, if the need arose.
January 8, 20232 yr 8 hours ago, Scorp007 said: Why would one use 5S2P when you have a 2nd MPPT being unused? Single point of surge protection for the PV strings? Beyond that, flexibility to use different panels on MPPT2 later due to availability, or just to use an 11A panel, maybe even a wind turbine. I'm thinking in part of future expansion, but I suppose it might not be an issue.
January 8, 20232 yr 10 hours ago, GreenFields said: Single point of surge protection for the PV strings? Beyond that, flexibility to use different panels on MPPT2 later due to availability, or just to use an 11A panel, maybe even a wind turbine. I'm thinking in part of future expansion, but I suppose it might not be an issue. We are on the same page. I would rather use each MPPT now on low power and only go 5S2P later if one wants to go beyond the 10 panels. Less cost without a combiner box. 2 x SPD's. Edited January 8, 20232 yr by Scorp007
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