Over the past few years, we have tried to switch our entire life over to full electricity. It’s something we have done in stages, but we are now pretty much done with the recent purchase of an electric car. A large driver for this is climate change and an effort to reduce our footprint. I was prepared to pay extra, but I have been pleasantly surprised at the cost savings we have so far encountered.
Outside of the solar, batteries and car, we have also installed a heat-pump hot water system, which we have set to run during the day from 7 am-3 pm, so it is essentially solar powered. We have also upgraded to LED downlights throughout the house and replaced the old ceramic stove with a Linarie induction 3-burner stove top. Despite its low price, I have been very happy with the stove. it’s a no-frills model, but it works great.
Key Summary Points
Solar alone reduced power bills by ~50% in winter and ~70% in summer
Despite less than ideal roof orientation, we still produce on a sunny day around 20kWh/day in winter and ~40kWh/day in summer.
The addition of a battery allowed us to be ~90-95% self-sufficient in summer, with only minimal energy drawn from the grid.
Adding a car, which we charge at home mostly (2kW wall plug), has caused us to start importing energy again during winter. However, we should produce more than enough in summer to remain self-reliant.
A key factor has been reducing the daily usage thru heat pump hot water, LED lights and other power saving appliances. Initial Usage = ~25 kWh/day. Power saving appliances = ~15 kWh With Solar = ~ 7 kWh per day Solar+Battery= <1 kWh per day Solar+Battery+Car= ~7 kWh per day
Solar Setup (6.6kW)
Sungrow Single Phase SG5K-D Premium
Canadian Solar CS3L-370MS (x18) 6.6 kW
Unfortunately, our roof is facing 136° South-East with a tilt of 23°, which is about the worst possible direction for maximum energy generation here in Southeast Queensland, Australia. Ideally, we would have a NNW-facing roof here to maximise afternoon sun, generally during peak usage.
We currently produce an average of 8,500 kWh per year.
If our panels faced north, this would likely be ~10,000kWh per year. Or about 2-5kWh extra/day in winter/summer
iSolarCloud iOS app – Notice the dual inverter setup, which is managed separately. Also, ignore the revenue numbers. Those are incorrect.
Battery Setup
Sungrow Hybrid Inverter SH5K-30
LG RESU12 – 13.1 kW total, 11.7 kW usable, – Charge/Discharge 5 kW/7kW max 3sec. – 10-year warranty with 60% guarantee
Basic backup power capabilities. Not instant (UPS), takes about 30sec to kick in, and covers lights and standard electric wall plug circuits only. Included: internet, fridge, TVs, microwave, computer, kettle, toaster etc. Excluded: Hot water, air con, oven and induction stovetop.
Dual Inverter setup means that solar and battery+grid data are monitored separately in the iSolarcloud app (see images above)
Not possible to charge the battery from solar if the grid is down, as solar is on a separate inverter
Battery price was subsidised by signing up for Origin Virtual Power Plant (VPP) scheme. We got $2,500 off the price + $20/month credit for supplying energy from battery back to grid. There are many VPP schemes out there now, and they are worth considering as they can get the price down towards that magical <$10,000 price point.
So far, Origin has discharged a total of 36.85 kWh over an 11-month period, which is about ~ 3.4 kWh/month, and roughly occurs on 3-4 days, ~1 kWh each time (0.13 to 3.35 kWh range).
Electric Car
2022 MG ZS EV 51kWh ‘Standard Range’
Currently getting ~14.7 kWh/100km on normal drive mode = ~347 km range
This is enough to go from Gold Coast to Brisbane and back on a single charge.
Charge at home ~1/week. Have used public charges ~1/month
Current at-home electricity costs 0.32 c/kWh = $16 to charge from grid (not solar/battery)
Petrol is ~$2.20/L, and the MG ZS petrol has an efficacy of 7.1L/100k = $54.67 for 350km or 3.4x the cost.
We top up the car during the day when it’s sunny and charge it overnight ~1/week.
I considered upgrading to a faster 7kWh charger, but the cost (~$2,000), combined with the fact that we can only produce a maximum of 5kWh from our single-phase solar system, didn’t make sense. That $2,000 is instead used to pay for green energy from the grid.
Charging overnight hasn’t been that much of a hassle.
Estimated Cost and Payback Time For Solar and Battery System
These are very rough estimates that make several assumptions of costs. There is a lot of variability with wholesale energy costs rising, while usage also varies. Despite this, I estimate that it would have taken approximately 5 years to pay off the cost ($4,300) of the Solar Panels. Combining the battery cost ($8,600+$4,300), I should now break by year 8 for the total system cost. With the 10-year battery warranty, this seemed more than acceptable to me. I could not justify spending over $10,000 on a battery system, as anything more than that would not break even.
Solar Usage Summaries
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