Two 5kW Inverters or One 10kW Inverter - 3 Phase

[clintyip]

I'm looking at having solar installed at my house next week (brand new property) – the installer said there is a global shortage on the Fronius Symo 10kW inverters so they're offering to do two three phase Fronius 5kW ones instead. The minimal wait for the 10kW one to come back in stock would be at least 3 months

Is there any performance changes with this? Our place runs on 3 phase power.

[Mike90250]

2 inverters give you some redundancy if one fails. On the other hand, it doubles the chance of a failure !!!

But I like being able compare 2 identical systems, If they are equally illuminated at some point in the day, an A-B comparison is super easy to do, and that may be the way you find a 200w panel that failed, but the inverter still works

[clintyip]

2 inverters give you some redundancy if one fails. On the other hand, it doubles the chance of a failure !!!

But I like being able compare 2 identical systems, If they are equally illuminated at some point in the day, an A-B comparison is super easy to do, and that may be the way you find a 200w panel that failed, but the inverter still works

Thanks for the reply! Is there any sort of performance issues I need to consider with two inverters instead of one? Such as being able to draw a theoretical amount of 8kW from the solar generated power during the day from appliances (such as central airconditioning).

The inverters here are all the Fronius Symo models (10.0.3 for the 10kW and 5.0.3 for the 5kW)

[Mike90250]

The output of the inverters will pretty much automatically share the load, selling everything possible to the grid.

Any appliance loads running, will subtract from what you sell to the grid. The engineering in the inverters and ohms law, insure the loads are well shared

[clintyip]

The output of the inverters will pretty much automatically share the load, selling everything possible to the grid.

Any appliance loads running, will subtract from what you sell to the grid. The engineering in the inverters and ohms law, insure the loads are well shared

So it sounds like the inverters these days can act as a "total 5+5" together rather than just two 5kW inverters on their own and does their own things?

[Mike90250]

each inverter has it's own solar array, and each will try to sell as much as it can harvest, to the grid.
Same if you had 10Kw inverter and your neighbor had a 10kw inverter, each inverter will sell as much as it can possibly harvest. Tied to the same grid !

[solar pete]

Howdy All, yep no issues with the 2 x 5's instead of one 10 and to me it says your dealing with a good installer as its more expensive to do 2 inverters than one, did they ask for extra money? because they are within their rights to in my opinion, cheers

[clintyip]

Howdy All, yep no issues with the 2 x 5's instead of one 10 and to me it says your dealing with a good installer as its more expensive to do 2 inverters than one, did they ask for extra money? because they are within their rights to in my opinion, cheers

hiya, thanks for the advice! No - they didn't ask for any extra money. They called me up to arrange an installation date and told me Fronius is not delivering any 8kW and 10kW Symo inverters until November at the earliest, so they offered me 2x 5kW Symos as the alternative with no extra charges.

25x Longi 370W Panels + 2x 5kW Fronius Symo inverters for $5999 AUD (~$4400 USD)

[theoak]

Depending on the brand, certain models only support 3 phase. You are installing 9.25 kWp total. You could probably get away with a lower sized inverter versus two 5 kWp inverters. It all comes down to which models support 3 phase though. If there was a model in the 7.5-8 KWp range that supported 3 phase, you could get away with just one inverter in that size range.