How much can you save with an electric car if your home has a rooftop solar power system? In this solar/EV owner’s case, a significant amount.
Transcript begins–
Hi, my name is Chris. I live in South-east Queensland in my fully electric house with my little family of three. Let me tell you a bit about my EV and solar setup.
About three and a half years ago, we made the decision to purchase a fully electric vehicle – the BMW i3. A few months after that, we installed our first solar system – a 10.8 kilowatt system; fairly large for the time.
But in the three years since installing that, we’ve been upgrading it; having seen great value from everything that it provides. So, we’ve upgraded the house to three phase and now have 28.8 kilowatts of panels on the roof. We can now produce up to 23.6 kilowatts of power, but unfortunately we can’t send it all back to the grid. So, whatever we don’t use is essentially wasted.
So, it’s all about moving loads to the middle of the day1. For the pool we use a smart switch. For the hot water, we use a timer and for the car we use the Zappi.
What does the Zappi actually do? Well, it charges your car, just like any other car charger. This one goes up to 22 kilowatts power, but it also has CTs2, which monitor the grid. This simply means that you can charge the car as fast as you’re actually exporting solar. So, you basically don’t pull anything from the grid unless you’re in a big rush.
Chris’s Solar And EV Savings
We’ve only spent $500 on servicing. So, we’ve saved at least a few thousand dollars there. We’ve driven over 138,000 kilometers. So, we’ve saved over $14,000 on fuel too. And the car drives as good, if not better than what it was when it was brand new.
And this car is a driver’s car. It’s rear wheel drive, built from the ground up as an EV and the space inside is absolutely magnificent.
So, what have I actually achieved here? Well, basically I don’t have a power bill anymore. I don’t have a fuel bill anymore. I get paid roughly a thousand dollars a quarter from my power company3 and I’ve got the best car I’ve ever driven.
I think what I’ve set up here is a really good example of what’s possible. My EV’s really old and compared to a modern EV, it’s got a very small range. I can only go about 200 Ks on the highway, but I’m doing over 40,000 Ks a year without any trouble at all.
Most people would agree that Australia’s EV uptake has been pathetic. We can only go up from here and I can’t wait.
Additional Commentary From Finn
Now, I will point out that Chris did pay $72,000 for that shiny BMW, which is more than he would have normally forked out for an ICE4 car. But nevertheless, based on his numbers, he is arguably still well ahead and EVs are only getting cheaper.
–Transcript ends
On a related note, discover the answers to 4 common questions Finn is asked about his EV and why your next car should be electric.
This segment is from SolarQuotes TV – Episode 10: The Ultimate Guide To Electric Vehicles – watch it to learn everything you need to know about electric cars generally. But for really comprehensive information on charging, check out the electric vehicles section on SQ.
For more SQTV episodes and solar energy related videos with a special focus on Australia, visit and subscribe to the SolarQuotes Youtube channel.
Footnotes
- Learn more about putting your solar energy self-consumption on autopilot. ↩
- CTs – Current transformers. ↩
- From feed-in tariffs. ↩
- ICE – internal combustion engine. ↩
About Michael Bloch
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Just to clarify, the a BMW i3 is the 2 door hatchback that looks a little like a Mini Cooper, a sort of modern VW Beetle? I was going to ask about price but Finn answers that question in the article – the BMW cost roughly 3x what most folk will pay for a sedan ICEV car. Why do I say car instead of leaving it at ICEV? Because ‘gas guzzling’ SUV sales are supposed to overtake car sales in the near future.
Chris says his EV is really old, but isn’t it only 3 years old? The average Australian keeps their car for a decade before replacing it. Okay if he’s referring to the design – the concept debuted in 2011, production started in 2013 (2014?), but there have been several models since so the whole ‘really old’ bit isn’t clear. The original model had a range of 130 km but the 2017 model switched from a 22 kWh battery to a 33 kWh battery. If it’s the 2019 model – which seems unlikely given the aforementioned 3 years, that has a 42.2 kWh battery and a range of 246 km. (The Tesla Model 3 has a 52.5 kWh usable battery and significantly more range).
All in all I’m a bit confused – seems like a massive capital expenditure with only modest savings to offset that, at least to date. Now if the car is retained for another decade, then the costs may reach parity.
All this BS about EVs average 500 km is the best for EVs with most modern petrol and diesel cars get 8 to 900 kilometres the batteries are worth more than the vehicle when it’s time to replace which makes another problem it’s easier to make petrol and diesel cleaner to burn then pollutant environment with battery waste in batteries ev car manufacturers and lovers of EVs a telling the biggest porky pie lies and misleading those customers for profit and it’s just a load of BS
Chris says We’ve only spent $500 on servicing. So, we’ve saved at least a few thousand dollars there. ”
I wonder what car he is referring to? I don’t know exact numbers but most Toyota’s cost probably less than $1000 for three years servicing.
It would also be interesting to see the numbers for what it cost for the 28.8kW system, plus the cost of putting 3 phase into his property.
I’m living in Melbourne and the Solar outputs vary tremendously from summer to winter. Some days in winter I’m lucky to get 1kWh from the panels. Vs a peak of 28kWh in summer.
Your point about solar output varying greatly between seasons is interesting – it’s not just limited to summer v winter though. Most months I get significantly above the average my installer advised. This month, due to every day being cloudy, cloudy and rainy, or cloudy, rainy and stormy, I’m averaging about 12% below the given average.
I only use two-thirds or so the average electricity for my area, have a large solar system – though nothing like a 28.8 kW one, yet already haven’t generated enough to fully recharge a BMW i3 on at least two days this month, and on no day this month have I generated enough for a Tesla Model 3 (55 kWh battery). Add in energy lost through recharging inefficiency and the numbers look even sadder. Thus for me, and barring an investment in a 28.8 kW solar system which I do not have the space for, or an extremely large battery system (the more expensive option), fully recharging an EV would be a 2 day process most months, sometimes as much as a week!
George, how far do you drive every day?
Unless you are on a road trip (in which case you aren’t charging from the PV on your own house) it would be rare to completely deplete the battery of an EV in a day. And even less rare to deplete it again the next day & the next. A PV system doesn’t have to fully recharge an EV every day – just a top-up overnight while you sleep.
If you do actually drive several hundred kilometres every single day, then perhaps an EV charged from a domestic PV system isn’t for you. The vast majority of people drive much less & their PV system is likely to be perfectly adequate.
Peter, infrequent trips, but about 200 km at a time. Depending on the model, the BMW i3.cannot do that range – the newest model can, barely. As I’ve mentioned elsewhere, the Tesla Model 3 can only manage 250 km of cold weather highway driving – 510 km of city driving in perfect weather. Problem is a lot of Australian weather is neither perfect nor cold. What impact does sweltering hot with high humidity and AC as essential have? Add in lots of motorway driving …
For a basic day trip in the area I’d be needing oh say 300 km as a minimum range, probably closer to 400 km to allow for driving around and looking around. The Tesla Model 3 can manage that distance, but only in perfect weather and with at least some city driving in the mix, but lets be honest, who wants to do a lot of city driving for a day trip? Thus odds are the car would run out of ‘fuel’ before getting home, and unlike a petrol engine it can’t be ‘recharged’ quickly.
As for top up\recharge overnight, that negates the benefit of solar panels, unless you have a huge battery system. Note for the Tesla Model 3 they’re claiming about 6.6r km per kWh so assuming my maths is right, about $16 for a ‘full tank of electricity’. Perhaps half the price of petrol yes, but not as convenient to access.
Servicing and fuel cost savings don’t make up for the massive depreciation difference (~ $30,000) between that car and an equivalent ICEV.
If we are going to compare cost of ownership, then compare ALL costs of ownership.
Depreciation is the single largest cost of any new vehicle. By a country mile. Leaving that out that inconvenient detail is at best foolish, at worst wilfully misleading.
Given the likelihood of more frequent and more intense ‘extreme weather’ events, I’m wondering what happens if an EV gets swept away by floodwaters and ends up both damaged and fully submersed for a period of time.
Does that kind of situation create new types of risk for SES workers doing ‘clean-up’ type work once the flood waters have receded?
MHHHH 138000 km in 3 years , Are you sure ?? AS George stated “”I’m a bit confused “
Peter, Is that a misprint? “A PV system doesn’t have to fully recharge an EV every day – just a top-up overnight while you sleep.”
Have I missed something, how do you charge an EV overnight from solar? (You didn’t mention batteries)
Ha, ha, Glenn, yes probably not the best comment! Posted in haste after George seemed to imply a PV system had to be capable of charging an EV from dead flat to full in a day.
Although, if you are charging overnight instead of during the day, you could argue that you are using the grid as a battery & just withdrawing some of what was input during the day. And if you are on a time-of-use tariff you can charge on the off-peak rate so it won’t cost a lot.
Now, to the point of economics of buying an EV.
I cannot make any EVs economical for my current driving situation.
Petrol would be have to at least $3.65/litre to just break even.
Or I would have to triple my driving distance (more wear and tear on the car) on the same price for petrol as is today.
transport.nsw.gov.au has a good comparator, I’ve actually plugged my figures into the website, it comes surprisingly close to what I used in my own spreadsheet. Petrol indeed has to be about $3.65/litre at my current annual distance travelled or I would need to triple my distance for the current petrol price today ($1.479/l for ULP91).
Problem is that I would have to trade in. I still need to find about $45,000 to make the trade…. is that worth it to save $28,000 making the switch to EV (8 years of fuel savings). I would still be $17k out of pocket.
However, that would offset about 1500 litres of petrol per year. Petrol releases about 2.3kg of CO2 when combusted. Since 1kWh of FF generated electricity releases about 0.656/kg of CO2, that means I would need to offset the 1500 litres of petrol with about 5500kWh of clean solar PV energy. I would need a PV system of about 4kWp to achieve it. That would set me back about $4000. That would have to be a cheaper way to offset my petrol use by generating more cleaner energy exported to the grid for others to use if I wanted to reduce my CO2 footprint. Has to be better than forking out $45,000 trade changeover and wait 8 years to get some of it back.
So, there’s are only two compelling reasons why EVs are purchased out of one’s own pocket
1. eliminate FF/CO2 use, being a real greenie and flip off the FF industry, basically an act of defiance to the status quo
2. fun factor of the EV’s performance (instant torque)
Otherwise, there is really nothing about having an EV that would make me rush out and buy one right now. Just another form of transportation. Still goes from A to B with same traffic conditions, not going to make my travel any special (maybe a just smidge of smugness doing something for the planet).
Otherwise, the only real way of getting an EV cheaply is that work provides it, some huge subsidy or a very generous tax deduction. Or, we get slugged with carbon taxes to incentivise people to seek cleaner energy.
Why not swap and go batteries like the gas bottles for camping and caravans?I have see a video of battery changes on taxis in China,car drives over a pit,robot removes used battery.New battery comes in carrying second newly charged battery and job is done in under 2 minutes all by automation.