Rookie design attached, requesting comments & recommendations

[rmsingh]

Hi guys,
I've put together a simple design for my entry into solar. This is just to get my feet wet.
Please take a look and let me know if I'm on the right track. I'm thinking that I might be better off to series the 3 panels.
The batteries are on order, but not the BMS, or controller/inverter.

 

[mopat]

Yep 3 in series probably OK, Powland has 145 VDC maximum. You should check low temperature correction factor to be safe.

 

[rmsingh]

Yep 3 in series probably OK, Powland has 145 VDC maximum. You should check low temperature correction factor to be safe.

I'm not sure what that is, but these panels are B grade and does not have any information other than what I have in the diagram.

 

[mopat]

not sure what that is

At low temperatures PV panels produce more voltage. This increased voltage should remain below the Powland voltage maximum.

Since you have no manufacturers data on cold temperature voltage increase it is commonly/safely assumed to increase 20%.

So, 3 panels in series (3 X 40.1 X 1.2) on a cold morning may produce 144.36 volts; this is below your units 145 volt maximum.

You could be on the "right track" with a bit more reading at this site (it is DIY) and using Google to understand things you do not know.

 

[Zil]

You diagram shows three panels connected to the CC in parallel. With three or more panels in parallel I use a fuse on each panel. Need to protect against two panels feeding into one panel if some kind of failure. With your panels maybe 20 amp fuse for each panel close to where they combine. In your diagram near the CC. I use one of these fuse blocks, panels to fuse terminals, CC to the positive stud.

 

[rmsingh]

Thanks for the response. As was suggested. I will series the panels. Maybe, I'll add the fuse or disconnect as well.

 

[mopat]

add the fuse or disconnect

Yep, it is very nice to have a PV disconnect, make it a breaker & it can add some disaster protection.

 

[Zil]

Correction. My recommending a 20 amp fuse for each panel is wrong, Your two panels shorting through a bad panel would be 20 amps. Fuse should blow if that happens. I use 15 amp fuses on mine. The fuse block I use feeds into a disconnect switch before the CC.