mikeinmaine
New Member
- Joined
- May 6, 2022
- Messages
- 3
Hi, I'm designing a ground array for my residential grid-tie-only use. I already have a 3kw roof array with a SMA grid-tie inverter and am looking to add production and save $$ by doing it myself. I'm a competent residential carpenter and electrician, and have used DC-only solar systems in the past.
My question is about sizing the strings for the Growatt MIN5000-TLX. I picked up a pallet of used Canadian Solar 235w panels (28) and their VOC is 36.9vdc and IMP is 7.9A. The max. input string open circuit voltage for the Growatt is 550vdc. I want to keep the string voltage as high as possible because the array will be 350' from the inverter and I want to minimize the gauge of wire between them.
Dividing 550/36.9=14.9 tells me that I can have 14 modules on each string with about a 37volt buffer under the inverter voc max. of 550v. The Growatt inverter seller says that I should have a minimum of 10%, or 55v, buffer under the max and therefore should have 13 panels on each string. I don't want to parallel and serial because that would bring the voltage down to around 250 and double the max amps across the wire.
Does it make sense what they are saying that I need to leave a 10% buffer between the max. theoretical VOC of the strings and the inverters 550voc limit? In what cases would the string voltage exceed its own theoretical max voc?
Thanks!
Mike in Maine
My question is about sizing the strings for the Growatt MIN5000-TLX. I picked up a pallet of used Canadian Solar 235w panels (28) and their VOC is 36.9vdc and IMP is 7.9A. The max. input string open circuit voltage for the Growatt is 550vdc. I want to keep the string voltage as high as possible because the array will be 350' from the inverter and I want to minimize the gauge of wire between them.
Dividing 550/36.9=14.9 tells me that I can have 14 modules on each string with about a 37volt buffer under the inverter voc max. of 550v. The Growatt inverter seller says that I should have a minimum of 10%, or 55v, buffer under the max and therefore should have 13 panels on each string. I don't want to parallel and serial because that would bring the voltage down to around 250 and double the max amps across the wire.
Does it make sense what they are saying that I need to leave a 10% buffer between the max. theoretical VOC of the strings and the inverters 550voc limit? In what cases would the string voltage exceed its own theoretical max voc?
Thanks!
Mike in Maine
