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I'm looking to install 10 x 320W panels on my RV. They have a Voc of 45.6V and a Isc of 9.1A. I will have a large 24V lithium LiFePO4 battery. My question is...which charge control(s) would work best for this system. My thoughts are 2 x 250/100's with 5 panels on each controller. Just not sure if I can use smaller units with a 24V system.
Hi D. You won't need 2x 250/100's. And those aren't cheap. Thank me later.. :)
In theory, each of your 320W panels could do 11-12A into 24V at typical charge V. In practice, and especially laid flat, you'll rarely (if ever) see > 10A. 2x of those panels in series would work fine for 24V batts. 10A is an easy figure to work with, so I shall..
Options..
*Strung 5S2P - 1x 250/100. Needs checking for panel temp & Voc.
*2S5P - 1x 150/100. Might help a little with shade, bit cheaper?
*2S & multiple smaller mppts, up to 5x. Best shade tolerance, more wiring, etc.
Run whatever you can think of through here: https://mppt.victronenergy.com/ Try with both spec-sheet & 'practical' figures to see the cost difference. Mix'n'match as you will. Your options, your money, your decision.. have fun choosing.. :)
Hi @djkarau,
Exact link: https://www.victronenergy.com/upload/software/VE-MPPT-Calc-3_3.xlsm
I heard there is a new online version of this also, cannot find it right now but this excel will work perfectly.
Contact your installer to help with this calculation, never spitball it. If it is a self install, contact MPPT supplier to help with this calculation, or follow @klim8skeptic advice: post datasheet of panels and min/max temp, someone will assist.
Hi Djkarau,
The 250/100 is rated for 2900w of panels @ 24v battery. A little bit over wont hurt, the controller will limit its output.
Depending on how cold it gets, and the panels temp coefficients, limits how many panels you can wire in series. Don't go over the mppt's input voltage limit of 250v, or the smoke will come out!!!!
Please post on how cold you expect things to get, and a link to your panels data sheet.
