stepping down voltage on solaredge inverters

[ggunn]

Yep, I think it had to do with having the 3 inverters not loaded evenly. Using the same P1101 optimizer for all the inverters had 2 of the inverters at about 120% and one at about 80% IIRC. I switched some of the panels to a P505 optimizer which allowed me to more evenly distribute the panels due to shorter required string lengths. Doing this brings the production up to almost the same as the 120k option (still down 1 MWh though) at the added cost of about 45 more optimizers.

I haven't seen the efficiency vs DC loading plots for these SolarEdge inverters, but others I have seen (SMA, I believe) show the efficiency pretty much flat from 1.0 DC:AC down to about 0.2.

 

[djr3203]

Actually you may want to check with the utility and see if they have any special requirements that if transformers are used they be wye wye. Many POCOs have "effective grounding" requirements, which IMO are hogwash but nonetheless would need to be complied with. Other than that I can't think of any reason to use a wye wye.

Replying to an old thread here but coming across this and on the west coast under PG&E they say interconnection has to happen as 4-wire if the system is 4-wire otherwise a "stabilizing" transformer has to be used which I assumed to be a zig-zag grounding transformer on the delta side. Doing a wye-delta would essentially mean you have an ungrounded system on the delta side? I would say if the inverter needs a 4-wire connection on the transformer then you would be looking at a wye-wye to interconnect with a 4-wire utility service. Also wondering why a delta wye with delta on the inverter side doesn't work.

 

[jaggedben]

Replying to an old thread here but coming across this and on the west coast under PG&E they say interconnection has to happen as 4-wire if the system is 4-wire otherwise a "stabilizing" transformer has to be used which I assumed to be a zig-zag grounding transformer on the delta side. Doing a wye-delta would essentially mean you have an ungrounded system on the delta side?

Be clear which sides you're referring to. A delta-wye transformer can be connected on the delta side to a grounded wye system. Just because it's delta at the transformer doesn't mean the system isn't wye grounded at the primary source.

I would say if the inverter needs a 4-wire connection on the transformer then you would be looking at a wye-wye to interconnect with a 4-wire utility service.

Not necessarily, from my understanding from discussions on this forum. (Granted, also not my job experience).

Also wondering why a delta wye with delta on the inverter side doesn't work.

The inverters usually want wye and will not operate without the neutral reference. But that can be separately derived.

 

[ggunn]

Be clear which sides you're referring to. A delta-wye transformer can be connected on the delta side to a grounded wye system. Just because it's delta at the transformer doesn't mean the system isn't wye grounded at the primary source.


Not necessarily, from my understanding from discussions on this forum. (Granted, also not my job experience).

The inverters usually want wye and will not operate without the neutral reference. But that can be separately derived.

A lot of three phase inverters are neutral optional but most still require that the 480 side be center (neutral) grounded wye.

 

[jaggedben]

A lot of three phase inverters are neutral optional but most still require that the 480 side be center (neutral) grounded wye.

You mean they use the EGC as reference, right? And the EGC still needs to be bonded to a grounded wye point. (Correct?)

 

[winnie]

Thank you! I got too confused reading through post about primary secondary sides. If you look at both sides like a power source it gets confusing where the primary side is.

The primary side is the one which gets energized first and which sets the voltage. This is the case even when power flow is from secondary to primary.

On PV systems the grid initially energizes the transformer and the grid sets the operating voltage. The PV inverter 'follows' the grid. So the grid side is the primary side.

Jon

 

[electrofelon]

I would say if the inverter needs a 4-wire connection on the transformer then you would be looking at a wye-wye to interconnect with a 4-wire utility service. .

I delta- wye would be the typical transformer for a PV system. You can feed a Delta primary transformer from a 4 wire or wye system. Some utilities want a wye -wye transformer used however to meet their "effective grounding" requirements.

 

[ggunn]

You mean they use the EGC as reference, right? And the EGC still needs to be bonded to a grounded wye point. (Correct?)

Yes and yes.

 

[harborrick]

Hey Everyone,

Looking for input from anyone who has stepped down the inverter voltage on a grid tied solaredge inverter. I am working on a project with 208/120V-3Phase-4Wire service where it seems like it makes sense to use a SE120KUS 120kW 480/277 grid tied Solaredge inverter. My question is regarding the stepping down of the inverters output voltage to match the grids voltage. Is there anything special to watch out for when doing this? Will a standard 150kVA dry type delta (grid side) to Y (inverter side) transformer work or am I missing something? Thanks for the input!

We would use a 480/277Y to 208 Delta Transformer for Solar or backfeeding. Must say this on transformer. We create a neutral at transformer. Neutral at transformer would be same size as your ground. Solar Edge only needs a neutral for referance. However a regular transformer will work. No need to bring neutral back to grid.

 

[BackCountry]

We would use a 480/277Y to 208 Delta Transformer for Solar or backfeeding. Must say this on transformer. We create a neutral at transformer. Neutral at transformer would be same size as your ground. Solar Edge only needs a neutral for referance. However a regular transformer will work. No need to bring neutral back to grid.

Depending on the application, often we don’t see the neutral brought in beyond the service disconnect for a 480v system. For 120/208 — the neutral is usually alive and well clearly for the 120v loads.

If this were me, I would likely use 25kw 120/208 inverters, with a neutral, and an combiner panel. I don’t believe the larger SolarEdge is worth it, when you factor in the transformer. CHINT makes a nice 25kw as well as the new SMA.

If RSD is required with your project, then SolarEdge is a viable option. If it isn’t, then I wouldn’t use SolarEdge due to the optimizer requirement.

 

[harborrick]

Depending on the application, often we don’t see the neutral brought in beyond the service disconnect for a 480v system. For 120/208 — the neutral is usually alive and well clearly for the 120v loads.

If this were me, I would likely use 25kw 120/208 inverters, with a neutral, and an combiner panel. I don’t believe the larger SolarEdge is worth it, when you factor in the transformer. CHINT makes a nice 25kw as well as the new SMA.

If RSD is required with your project, then SolarEdge is a viable option. If it isn’t, then I wouldn’t use SolarEdge due to the optimizer requirement.

I would tend to agree with you. However when we use 5 or 6 40kw plus ,its a huge price difference.

 

[BackCountry]

I would tend to agree with you. However when we use 5 or 6 40kw plus ,its a huge price difference.

For sure, which is why RSD is such a pain. I’m seeing a lot of new articles about long term viability, and it doesn’t look good. More connectors = bad.

 

[BackCountry]

I would tend to agree with you. However when we use 5 or 6 40kw plus ,its a huge price difference.

For sure, which is why RSD is such a pain. I’m seeing a lot of new articles about long term viability, and it doesn’t look good. More connectors = bad.