brandonoh777
New Member
- Joined
- Oct 26, 2020
- Messages
- 18
Hello i have a 100% made form used components grid tie system. 30 250W Canadian solar used panels and a used APP PVI 3.0 inverter. got everything hooked up and mostly running well but i am having the dreaded RISO low messages especially in the mornings with moist conditions.. Right now its just one string of 7 panels and one string of 8 on each of the separate MPPT channels. I have read and watch YT videos on why this happens and i am understand it more and more as i go along.... so it comes form low insulation/resistance conditions (for whatever reason usually moisture) from the DC side to earth ground.. problem i tested it a day or 2 with no ground on the DC side (yes i know this is a not recommended condition) and the panels pretty well electrically insulated form the actual ground (the frames) and frames isolated form each other. And i still get low riso values for the 1st third of the day. How can current be leaking to earth when the panels are isolated from the earth and no ground is connected to the inverter? I have seen the voltmeter each lead to frame test (in direct sunlight) and your supposed to see rapidly decreeing voltage readings down to near 0 and stay there if everything is the way it should be.... i will be testing each panel with this test in the future. Have any of you had similar problems with transformerless grid tied inverters? are used panels likely always going to lease some current? and the min value seems to be quite small at least for start up....the crazy thing is if it eventually boots up and gets running and then is directly rained later on in the day doesn't give any riso alarms and keeps right on going.
brandon
brandon