DIY solar panels.

Thread Starter

Cobynew

Joined Sep 17, 2021
2
A1FDB1E9-4190-4A3B-882D-EEEF04AA1AFC.pngI have 16 of these bp3125j panels, and I bought a grid tie inverter that requires 45-90vDC input. Everything I can find online about these panels says they have a 600v maximum system voltage, yet on the bottom left corner it says it’s fm approved for 48Vdc. Can someone please help me make sense of this…. Here is my references for the bp3125j information. IT DOESN'T SAY ANYTHING ABOUT 48Vdc ANYWHERE IN THESE PDF!!!
https://powerupco.com/site/wp-content/files/Solar Modules/BP Solar/BP 3125J.pdf
http://www.effectivesolar.com/PDF/bp/BP-3125.pdf
https://www.solarpanelsaustralia.com.au/downloads/bpsolar_bp3125.pdf
 
Last edited:

Ian0

Joined Aug 7, 2020
3,760
"Class II" is accompanied by with the symbol for "Class II" insulation (double insulated), so I think it referring to two different things.
"Maximum system voltage" means the maximum voltage between any terminal and ground, which might occur when connecting several panels in series.
 

boostbuck

Joined Oct 5, 2017
81
Your panels are nominal 12V panels. I suggest you connect your sixteen panels in four parallel strings, of four panels in series in each string. This gives a nominal voltage of 48 volts and an open circuit voltage of about 88 volts and a Vpmax of about 65 volts, which fits the spec of your inverter.

I'm not clear if these panels incorporate series diodes. Probably not, from my experience with early BP Solar. You will need to add blocking diodes on the strings if diodes are not integral to the panels.
 

Thread Starter

Cobynew

Joined Sep 17, 2021
2
Your panels are nominal 12V panels. I suggest you connect your sixteen panels in four parallel strings, of four panels in series in each string. This gives a nominal voltage of 48 volts and an open circuit voltage of about 88 volts and a Vpmax of about 65 volts, which fits the spec of your inverter.

I'm not clear if these panels incorporate series diodes. Probably not, from my experience with early BP Solar. You will need to add blocking diodes on the strings if diodes are not integral to the panels.
Thanks for helping me out with this, the panels come with bypass diodes however I will invest in blocking diodes to be safe.
 

Juhahoo

Joined Jun 3, 2019
250
Thanks for helping me out with this, the panels come with bypass diodes however I will invest in blocking diodes to be safe.
You should check out these to squeeze the last bits of energy out from the panels. These are so called "ideal diodes" which will significantly reduce the amount of power lost by conventional diodes.
https://www.amazon.com/SANON-Charging-Irrigation-Protection-Parallel/dp/B088CW5LYD
or
if you are a hobbyist you can build one yourself with this chip:
https://www.analog.com/media/en/technical-documentation/data-sheets/ltc4359.pdf
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