BackCountry
Electrician
- Location
- Southern California
- Occupation
- Licensed Electrician and General Contractor
I’m trying to plan for a job that we just bid, and I’m at a decision making point on how we’re going to tie in with our local utility.
Existing large ranch with two existing single phase 200A 240v 3w services. Our calc shows a 30kw sized PV array will handle the existing usage, we have net metering aggregation here where one meter’s backfeed can offset another meter’s consumption on the same parcel.
We’re looking at a 125A backfeed, which means we need to either use two 15kw 1ph Fronius inverters (only ones made that high in single phase to my knowledge), the tie in is 400ft from the array, so I’m thinking we take the voltage as high as we can on the DC side to overcome distance. We then either drop a third meter in with a 225A bus and derate the main breaker to 150A, thereby giving us a 120A backfeed capacity, or...
What I would much rather do is use a 35kw SMA tripower 480v 3ph inverter, and then either evaluate the cost of 3ph 480v service (the existing utility transformer is a 50kv single phase) which may be cost prohibitive, or not place a step down transformer in.
I could also upgrade the existing 200A panel to a 400a Siemens solar backfeed panel with two 200A disconnects and a third PV disconnect so no line side tap is required.
I appreciate any insight and wisdom. This will be ground mount, and is in an agricultural area. If I could have my way, I’d get a third 480v 3ph 4w service installed on a new meter and use a larger 3 phase inverter and call it a day. I’m not sure that’ll be possible or cost effective from our utility (PG&E).
Existing large ranch with two existing single phase 200A 240v 3w services. Our calc shows a 30kw sized PV array will handle the existing usage, we have net metering aggregation here where one meter’s backfeed can offset another meter’s consumption on the same parcel.
We’re looking at a 125A backfeed, which means we need to either use two 15kw 1ph Fronius inverters (only ones made that high in single phase to my knowledge), the tie in is 400ft from the array, so I’m thinking we take the voltage as high as we can on the DC side to overcome distance. We then either drop a third meter in with a 225A bus and derate the main breaker to 150A, thereby giving us a 120A backfeed capacity, or...
What I would much rather do is use a 35kw SMA tripower 480v 3ph inverter, and then either evaluate the cost of 3ph 480v service (the existing utility transformer is a 50kv single phase) which may be cost prohibitive, or not place a step down transformer in.
I could also upgrade the existing 200A panel to a 400a Siemens solar backfeed panel with two 200A disconnects and a third PV disconnect so no line side tap is required.
I appreciate any insight and wisdom. This will be ground mount, and is in an agricultural area. If I could have my way, I’d get a third 480v 3ph 4w service installed on a new meter and use a larger 3 phase inverter and call it a day. I’m not sure that’ll be possible or cost effective from our utility (PG&E).