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Beginner questions about panel specs and application sunpower (spr-x21-345-c-ac) 345 watts

hbizzle27773

New Member
Joined
Nov 6, 2023
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4
Location
USA
panel photot.pngsunpower panel info.png
Hey there folks, i apologize if im being repetitive in that, full disclosure, i have tried to ask about this panel once before however i dont think i was asking the right questions and as a result i decided i would try again.
I was fortunate enough to be gifted four of these panels by a friend who didnt have use for them but knew i was trying to come up with a solar system for my fifth wheels rooftop. Now they all came with a microinverter each, but if theres one thing i was able to take away from my first post, was that, for my application, i would be much better off removing those and using the panels like, i guess any other panels minus the microinverter. i now also know that that is literally as simple as it sounds, but im wondering if it has something to do with where i then get confused.

So from what i understand, when looking to apply panels to any particular setup, some of the more important specs simply dont appear to be listed here and if they are then i am not reading it properly. but instead of fumble about trying to explain what i think i should be seeing so that i know how to proceed, i was hoping perhaps someone could help me understand where on the above label, if its there, i could find the information about the following:
1. I am working with a 12 volt system, does it look like i would be able to use these panels, i guess would that be nominal voltage?
2. the short circuit voltage
3. the open circuit voltage

So, then im hoping, with this information, i can figure out if perhaps i can use my current 12 volt charge controller on board with these panels, or if i need to find something else.
any information would be greatly appreciated
 
You need to find out the specs of the DC side of the panels, the specs you have are for the micro inverter ac side.

This is the possible spec but you have to get it confirmed.


Maximum Power (Pmax)
335 Wp345 Wp
Voltage at Maximum Power (Vmpp)
57.3 V57.3 V
Current at Maximum Power (Impp)
5.85 A6.02 A
Open Circuit Voltage (Voc)
67.9 V68.2 V
Short Circuit Current (Isc)
6.23 A6.39 A
Panel Efficiency
21 %21.5 %
Power Tolerance (Positive)
+ 5 %+ 5 %
 
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Hmm ok so what does that make them 48 volt panels? I apologize for my lack of knowledge, but would it be possible to use this panel or rather 4 of them with a 12 volt battery system?
 
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Now you have the specs (but note you need to be 100% certain) then you need to look at the specs of MPPT's to see which ones with a 70V panel will charge a 12V battery. That's if you put them in parallel, in series the voltage is additive. so 2 give 140V, 4 give 280V.

Suggest you play around with this


Based on the calc above there are several solutions for a 12v battery with the panels in a 2P2S array.

This is one

 
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