Microinverter voltage rise

[unosuave]

I have recently install a 7.5 kw PV array and had a problem with the microinverters tripping off due to high voltage, 257 volts line to line. I made several measurements and found the electric co-op incoming line.....250 volts line to line. It is within ANSI spec +- 5% of 240. So no hope in getting electric co-op to lower line voltage. I tried! So... the only other choice is to lower my voltage rise (drop) to the interconnection 225 feet away. Found this calculation helpful in determining needed wire size to lower voltage rise (drop) to 1% or less. http://solarprofessional.com/article...stems/page/0/1

Good Luck!

[Mike90250]

To verify if there is too much resistance in your power feed from the Grid, at night, turn off much of your gear, and measure the line voltage. Then turn as much as you can, ON. the microwave, the air conditioning you want to load the lines down as much as possible, then measure the line voltage. if it's dropped more than a couple volts, you have a problem.

Or there is a high resistance in the loop from the PV - your breaker panel, measure voltage both at Inverters and then the breakers after sun is fully on the panels. more than a couple volts difference, you call the installer to fix it.

[Sunking]

Not going to work out very well if I understand you correctly. The inverter voltage has to be higher than the utility in order to push current. ANSI does not have anything to do with Utility tolerances as that is dictated by NSEC which is +/- 10% line regulation. Sounds like you are on a rural CooP?

[DanS26]

Just curious if you have solved your voltage problem?

When I was designing my ground mount arrays, they were over 250' from the POCO interconnect. I wanted so badly to go with micro inverters...but the wire sizing alone to avoid voltage rise/drop problems would have cost more than the string inverters. So I ended up combining DC strings at the arrays and home running high voltage DC to the inverters.

I was leery because I'm also on a rural REMC and the voltage swings almost every day to the high and low 5% maximums. So far no voltage clipping going on but it is a wild ride every day.

[bcroe]

I have recently install a 7.5 kw PV array and had a problem with the microinverters tripping off due to high voltage, 257 volts line to line. I made several measurements and found the electric co-op incoming line.....250 volts line to line. It is within ANSI spec +- 5% of 240. So no hope in getting electric co-op to lower line voltage. I tried! So... the only other choice is to lower my voltage rise (drop) to the interconnection 225 feet away. Found this calculation helpful in determining needed wire size to lower voltage rise (drop) to 1% or less. http://solarprofessional.com/article...stems/page/0/1 Good Luck!

I had the exact same problem. If you are too close to the trip point, changing wire may
not solve the problem. I see 2 ways to solve the problem. One is reprogram your inverter
to trip at a higher voltage. The other is use an auto transformer (or a pair) to step down
the line voltage some 10 volts lower for the inverter. Not a great solution since the auto
trans will consume some power all the time its connected. Bruce Roe

[DanS26]

These rural REMC's are really different. I can tell when people get up in the morning...come home in the evening....turn on heat or AC....go to bed. Lots of big motor loads, etc on long distance single phase lines. Got to be hard for these rural utilities to control things.

My neighbor does a lot of welding....when he turns on that machine...wow!