diy solar

diy solar

Iso high leg delta offgrid inverter.

As was stated in my original post. I already have 3p 415v power in my shop. I also have 120/240 split phase. I was just wondering if there was a simpler way to achieve both split phase and 3 phase in the same system. High leg delta seemed like an elegant solution to this. As far as phase imbalances go, as long as only 3 phase loads are run on the 240 legs, to my understanding it should be fine. The 120/240 split phase would have a seperate inverter for each leg so these loads should not imbalance the 3p as long as I don't overload the inverters. Unlike rotary generation with each leg having its
own inverter all loads would not need balancing, only 3p loads would require an even balance as these loads are returned to a different inverter than they originate in. ( at least this is how I understand it please feel free to correct me if I'm overlooking something) I am passably familiar with grid 3p rotary generation, as well as very familiar with split phase 2 inverter offgrid power as I have been offgrid for 20 years and also work in power generation. The reason high leg delta seemed like such an elegant solution was also because you don't end up having to transform any of your power after inverting it which would naturally be more efficient.


Passably familiar with rotary 3p⬇⬇⬇⬇
 

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As was stated in my original post. I already have 3p 415v power in my shop. I also have 120/240 split phase. I was just wondering if there was a simpler way to achieve both split phase and 3 phase in the same system. High leg delta seemed like an elegant solution to this. As far as phase imbalances go, as long as only 3 phase loads are run on the 240 legs, to my understanding it should be fine. The 120/240 split phase would have a seperate inverter for each leg so these loads should not imbalance the 3p as long as I don't overload the inverters. Unlike rotary generation with each leg having its
own inverter all loads would not need balancing, only 3p loads would require an even balance as these loads are returned to a different inverter than they originate in. ( at least this is how I understand it please feel free to correct me if I'm overlooking something) I am passably familiar with grid 3p rotary generation, as well as very familiar with split phase 2 inverter offgrid power as I have been offgrid for 20 years and also work in power generation. The reason high leg delta seemed like such an elegant solution was also because you don't end up having to transform any of your power after inverting it which would naturally be more efficient.


Passably familiar with rotary 3p⬇⬇⬇⬇
WTF is that thing on the sling?
 
I did Google image search on it, and "Visually Similar" images were all shafts with turbine blades.
But my vote is an armature. Given the concrete around, I'd guess for a hydro plant.

 
Would be convenient if inverters could be synchronized with 90 degree phase angle, but the ones I've seen are only 180 degree or 120 degree. Sunny Island does it with digital communication over CAN bus.

What I would have liked to do is use two split-phase for 120/240V, and a 3rd Sunny Island at 90 degrees plus a transformer to make high-leg.

Toroid transformers are relatively efficient, but could overload an inverter or breaker when first connected. I've been able to use a 9kVA toroid on one 5kVA inverter without problems.

Since my system is grid-backup with split-phase grid, I haven't been able to think of a way to connect 3-phase system to it except to just a single Sunny Island. If I could step 240V down to 208V and feed it into two legs that would deliver more power, but there is a chicken-and-egg problem presenting in-spec 3 phase to the inverters so they will connect in the first place.

For off-grid, perhaps three, 230V Victron inverters could be wired for 3-phase Delta. Use a transformer with center-tap grounded to make it high-leg delta. The 3-phase wouldn't go through transformers (except any inside the inverters.) Only imbalance in 115/230V split-phase would use the transformer. Same should work with European model Sunny Island. Normally for 230/400Y but I don't see why they wouldn't also work for floating 230 delta SO LONG AS no generator or other source connected to AC input, which has only one relay isolating "Line", none for "Neutral".

Using 230/400Y for the shop and a transformer to create split-phase 120/240V is probably better way to go.
 
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