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Question about building the Classic 400 Watt Solar Package

davidanoack

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Dec 14, 2020
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i purchased and read cover to cover your book on Mobile Solar Power and am following the blueprint for the

The Classic 400 Watt Solar Package

to add power to my home workshop. I currently have four (4) Renogy 100 watt solar panels feeding a Renogy Rover Elite 40A MPPT charge controller. The charge controller is connected to two (2) lithium iron phosphate batteries which are connected in parallel. The inverter is Renogy 200 watt.

I acquired two (2) additional Renogy 100 watt panels which will make the number of panels six (6). I believe I can just add them to the array with no other changes to the system. Is this correct?
 
Assuming 12V system.

40A * 12V = 480W
40A * 14.4V = 576W

Your SCC likely lists the maximum wattage it can supply for a 12V system, which likely varies from the above.

It's possible the bulk of your array will not be utilized at peak solar, but it will maintain its peak for longer due to the excess panels.

The new panels need to be connected the SCC in the same manner as the other 4. If all 4 are in parallel, then add the 2 more in parallel. If in a 2S2P configuration, your 2 new panels should be installed to make a 2S3P array.

If your charger is PWM, you MUST put all six in parallel.
 
Assuming 12V system.

40A * 12V = 480W
40A * 14.4V = 576W

Your SCC likely lists the maximum wattage it can supply for a 12V system, which likely varies from the above.

It's possible the bulk of your array will not be utilized at peak solar, but it will maintain its peak for longer due to the excess panels.

The new panels need to be connected the SCC in the same manner as the other 4. If all 4 are in parallel, then add the 2 more in parallel. If in a 2S2P configuration, your 2 new panels should be installed to make a 2S3P array.

If your charger is PWM, you MUST put all six in parallel.
Is 2S2P or 2S3P better than putting them all in parallel? My system is 12volt. I’ve been trying to follow the “Classic” configuration I mentioned earlier but am not locked into it. Thanks, DN
 
Parallel suffers less penalties when shading is a factor.
Serial can slightly improve low-light (dusk, dawn, haze, light clouds) charging.
Series has lower voltage drop (power loss) due to resistance in the wiring.
 
The Renogy MPPT controller that you have is rated for a max input of 520W for a 12V system and a max input voltage of 100V. Each Renogy 100w panel has an open circuit voltage of around 21.5v, so no more than 4 in series to keep the voltage under 100v. Six panels would be considered to be mildly overpaneled to the Renogy spec, but it will likely work fine, you just wont take advantage of all the available power, if you were ever to come so close to ideal conditions that your panels generate more than 520W. My experience with the similar HQST panels is that I never expect to see 520w out of the 6 panels I have. Based on the numbers, I'd suggest a 3S2P wiring of the panels to minimize the need for heavy gauge wire and fuses.
 
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