Quote for off-grid near Canberra

Hey all,

Building a house just outside of Canberra (Sutton, NSW).

Got a quote with two options that would love a review of:
15kW 1Ph Selectronic Output + 30.7kWh BYD L-ion Storage + 9.8kW Trina Solar

15kW 1Ph Selectronic Output + 28kWh PowerPlus L-ion Storage + 9.8kW Trina Solar

Many thanks in advance,


Sounds like a fun project Tom. Assuming you’re going to be fully off grid?

What is the trade off between BYD and PowerPlus @Svarky? Does the pricing look reasonable? Also, I would have thought you’d want a bit more solar for that size battery?

Tom, I trust the company quoting has done a full assessment of your energy usage to come up with that sizing?

Tom, these quotes seem rather high for this type of system.

The larger 15kW SP PRO uses a 120V battery system so it is more expensive than the more common 48V systems.
Why do you need a large 15kW inverter? You must have very high peak loads?
Does this include a backup generator?
What solar inverter did they specify, Fronius 8.2kW?

Also, as @Marty highlighted, the solar array seems undersized in comparison. Is the solar array North facing with a decent tilt angle?


Yeah we have done an assessment of the usage (based on the new house though, as we currently live in a tiny place without a dishwasher/induction stove/etc):

I think the 15kW inverter is because of the peak loads and we will have a backup generator (we need to source that separately though so it’s not include in the price, any tips on which one to get would be great!).

For the solar inverter it is the Fronius, here are screenies of the breakdown for both options:

And the solar array will be north facing and on a pitched roof:

Thanks so much for the questions and thoughts!


Ok, I see they are using 2 x SP PRO 48V battery inverters, not the larger 15kW 120V SP PRO. This makes more sense now.

The load table is very good, nice detail, just wondering what capacity the split system A/C is? It must be a large central ducted system to draw 4.5kW?

An off-grid system of this type and size is not an easy job but it does seem to be a little on the expensive side. Although without knowing about the complexity, cable runs, trenching required, etc, it’s hard to say. Does the price include the Federal government STC rebate?

Note, I would personally go with the Powerplus battery option. I’ve been using them for years and had no issues at all. Very good Aussie made battery system