Design Help - Grid Tied Hybrid Solar Setup with Battery Backup

[BrutusB]

Basics.
Location: Victoria, Australia
Grid Power: Single Phase - 240v - 100amps
Usage: Home
Consumption: Average Daily = 21.37 kWh


Panel:


The Brief.
I want to connect solar to my house for a number of reasons:

• Back-up/Redundancy - I want to make sure I can run the majority of the house on backup power that's automatically switched (Help needed here - See below)
• Saving Money (don't need help/advice on this)

I've contacted a Solar retailer and they've advised the below would meet my needs:

6.6kw Hybrid System

• 15 x Jinko Solar Tiger Neo N-Type 440W Black Frame 108 Half-Cut Cells Mono (JKM440N-54HL4R-V)
• 1 x Inverter- Growatt SPH 5kW 1 Phase 2 MPPT Hybrid BL-UP (SPH 5000TL BL-UP (AS4777-2 2020))
• 1 x Monitoring Inbuilt Wi-Fi

On top of this I'll be sourcing a LiFePO4 48v 10KWh/200AH battery of some form.

Considerations.
1. All grid connected/tied inverters/Panels must be on the approved lists:
- Inverters - https://www.solar.vic.gov.au/sites/...ter-product-list-as-of-22-September-2023.xlsx
- Panels - https://www.solar.vic.gov.au/sites/...nel-product-list-as-of-22-September-2023.xlsx
2. All work must be completed by a qualified/licensed Electrician (labor is expensive - expect. $100 per/hr)

The Problem.
The back-up/UPS power output for the majority of inverters is limited to somewhere between 20-30amps and most require a ATS/Breaker of some form limited to the same amperage.

This is not enough to run the whole house and no electrician is going to connect the whole house to a ATS of 30 amps considering the theoretical max usage into the house is 80-100amps (Stove/Aircon/Microwave/Hairdryer all on at the same time etc.).


Solutions I've thought of but don't think are ideal:

1. Bigger inverter - Still limited to 30amps output (remember the list above)
2. Multiple inverters - Am I going to need 3 x SPH5000?
3. Mix of inverters - Use the SPH5000 connected to the grid then something like a 'uncertified' inverted specifically for the back-up power and leave it off the grid e.g. https://www.ebay.com.au/itm/1658859...uid=H4ZGbnq5QSy&widget_ver=artemis&media=COPY

The question.
How can I solve this problem?

Thank-you in advance.

B.

 

[Thersites]

I'm not equipped to answer the full scope of your Q, but I have been exploring similar considerations with different parameters. You are kicking up against the limitations of DC-coupled batteries, which though they are more efficient than the alternative (AC-coupled batteries)...they are nevertheless - IF they have capacity for a sufficient discharge rate (and I don't think your single one will) - still going to be throttled by the hybrid inverter's capacity. So a possibility might be a couple of paralleled AC-coupled batteries if you are sticking to your inverter recommendation.

My second thought (which was actually the first) was - might you have over-specced your requirements? If they were not quite so demanding, they'd be easier to meet. Is absolutely everything vital throughout a power cut? 23kW is an eye-watering amount to plan for. If you lowered your sights a little and went for a different inverter, then the Delta H10E in the setup described in https://www.solarquotes.com.au/blog/delta-hybrid-inverter-mb1936/ might suit. The 4 MPPT channels is very attractive to me, and I'd have one in a shot if they were distributed in the UK.

 

[cat2devnull]

How did you go with this?
I would have thought that 2xSPH5000 would do the job.
That gives you 10kVA of output and up to 170A of battery charging (8000W).
Most 48v LiFePO4 batteries can support up to 100A so you would probably want to run at least 3x5kVA batteries in parallel.
The Growatt inverters should support the RUIXU batteries which are pretty nice.