Grid Tied Grief!

[gtuplin]

[QUOTE=sunnyguy;n327915]Interesting. So how common a problem is this with string inverters in general? You don't really see efficiency curves based on grid voltage, just DC voltage.

According to Growatt the problem of high voltage is not the common issue but in most cases line voltage is very low so they were designed around that however I was told that in the next line the range will be adjusted to accommodate the high range. Most likely a software re write.

[gtuplin]

Glad also you found the problem........but I am interested why the house inverter is not affected? I know you have two transformers, but are they not supplied by the same distribution line? Same number of windings in a 25 kVa as a 50 kVa.....voltage should be the same.

The only thing that we can come up with that makes sense is that the 4 inverters run off the 50kv split line but have no load, strictly outflow where the house site has a heavy load perhaps bringing it into a better range for the software to manage. There is a small outflow from the house inverter but most power produced is consumed but that being said now the inverter with the transformer in the field is about 10% more efficient than the home system. It is possible that a transformer on the house inverter would beneficial as well.

[DanS26]

What is the wire size between the inverters and the common point of connection with Hydro? The buck/boost transformers may only be a band-aid for poor wire design. Would it not be more efficient and less costly to have one buck/boost at the AC combiner rather than at each inverter?

[gtuplin]

Everything is mounted on a 16 foot wall, main ac disconnect, splitter, 4 individual ac shut offs then direct to inverters. Not sure what the actual wire size is but its the recommended/ code and seems to satisfy the inspector.
The Buck Boost for a 200amp service was not available and had to be made at some cost I might add so the simplest solution was the individual approach and those were in stock, and it was thought that if this line was ever to be joined at the end to another grid it would likely stabilize the grid power voltage and this would be easier to bypass. I also had some space issues as the system is basically complete and to accommodate a large and very heavy transformer I would have had to make a small pad and covered area that would require a new application from transmissions for a building variance. Really wasn't interested in that considering the time it took to get the project approved in the first place, really looking forward to being just fully up and running.