Hello,
I’m on USA grid and have a grid tie system with a MultiPlus II. Grid connects to AC in on MP and it works great, but the single MP feeds one leg only. Could I stick an autotransformer between the grid and MP (connect grid to AT and AT to MP’s AC in) or is that a bad idea?
Found someone asked the same thing a few years back (link below) but it was never answered so asking again.
Ok, so doing this - Putting an auto transformer between the multi and the grid- will balance the load of the multi AC in between the 2 grid legs. If you have additional loads on L2 in your house, then these will be added to the 50% of the multi loads on Grid L2.
Given that your domestic loads are unlikely to cause any problems with the grid, there is no real advantage in doing this except in the case where you are on the end of a long subscriber line and have limited loads on L2. In this case, balancing your loads between L1 and L2 will reduce voltage drop.
However, apart from losing power to the loads on L2 in the event of grid loss, you can achieve the same effect by balancing your loads between L1 and L2 in the distribution board.
Thanks. That’s basically what I thought.
I can use time of day pricing and get cheaper electricity overnight and electricity during peak times is very expensive.
My system isn’t too large and can’t power the whole home with multiple large appliances running. It is for financial purposes, not grid independence, so making it larger didn’t make financial sense.
The MP II is a long run away from the house and connected by a single 12AWG wire that would be hard to replace so I figured if I put an AT in I can run twice the power over that wire if pushing 240 instead of 120 meaning I can use more stored energy and less grid energy during peak times.
Thanks
Edit to add: I just re-read your comment and I will lose power to all loads if grid fails because AC is only connected to the MP on AC in so the MP will cut power to the house entirely if grid fails to prevent hurting linemen.