My 1220 watts of panels in series have a VOC of 160, and VMP of 129, but I can’t cipher the VDC. The GW says it needs 150 VDC to start, and MPPT range is 120-250 VDC. Not sure how to compute VDC for my panels, as it isn’t mentioned. Besides a brain, what am I missing??
Growatt 24/3000- 150 VDC?
- Thread starter getalab
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iamrich
Solar Addict
Which version of the Growatt is this? I thought these units maxed out at 145vdc?
iamrich
Solar Addict
Found it, SPF 3000TL LVM-ES. Maybe I am not understanding the question, but you want your panels to series together to be greater than 120vdc, but less than 250vdc. I would shoot for 200voc so you have plenty of wiggle room.
iamrich
Solar Addict
I think in this case Vmp=VDC. (holding my own conversation 
)
)That was my wonderment, does VDC=VMP..appears you are correct.. found another spec sheet with different numbers, but still use VDC instead of VMP.I think in this case Vmp=VDC. (holding my own conversation
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iamrich
Solar Addict
Just make sure you leave yourself some wiggle room. You do not want to exceed the voltage max. My panels for instance have VMP 30.3vdc, but they routinely run between 99-104vdc from my three sets of three. My SCC has a 150vdc max input, and the VOC for my panels is 37.6vdc, so in theory I could run x4 at the VMP rating, but at VOC it would be 150.2vdc (and that's before any temp correction) which is a no go (insert frowny face). Better to be comfortably under and just add more strings IMO.
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