Sold on solar

David Stone recently made the transition to having a solar-powered home and an electric car. He says it’s the perfect combination.

When Omaha resident David Stone drives past a petrol station and sees the advertised price of unleaded, he just grins. That’s because these days David has little use for petrol and runs his own car mostly for free.

That happy state of affairs occurred back in September when David installed solar panels on his roof and splashed out on a new Tesla electric car.

Solar energy not only powers all the appliances in his home, it also charges the Tesla, heats his spa pool and runs his air conditioning. David even makes money by selling the surplus electricity he generates back to the national grid, which is monitored in real time using a mobile app on his phone. When Mahurangi Matters called, he did a spot check and found that even on a cloudy day he was generating 2kW of electricity, using 1.6kW of that to power various appliances in his house and exporting 95W to the grid. The remaining power was charging a battery to store electricity for use at night.

But the electricity cost savings are only part of it, as a keen environmentalist David was eager to do his bit to “save the planet”.

“By using solar, we are not adding in even an infinitesimal way the need to fire up the coal-fueled Huntly power station,” he says.

He and his wife are both parents and grandparents and the cliché about what sort of world they want for their grandchildren bears heavily on them both.

“When we are asked ‘Poppa and Nanna what did you do about the climate crisis’, well this is something we have done and something the average Joe Blow can do as well,” he says

David reckons that if, say, just 20 per cent of New Zealand homes were similarly equipped with solar panels then we would simply eliminate the likelihood of any kind of energy shortage that would demand harmful environmental interventions like building more dams or burning coal.

But there are some steep upfront costs, right?

Indeed. David spent $38,000 for 24 solar panels and associated hardware and then forked out a further $82,000 on Tesla Model 3 with a dual motor.

He admits having money in the bank to take care of these expenses made the decision easier. Money in the bank was earning a piffling 0.5 per cent net interest. The same money invested in solar and an EV makes an effective 9 per cent return.

“Where else are you going to a secure 9 per cent return on your money?” David asks.

This means that it could well be worth Joe Blow borrowing the money to make the upfront investments. And, of course, Joe need not necessarily have to buy quite such a nice EV. Just going for the Tesla Model 3 single motor option brings the price of the car down to about $67,000.

Have the economics worked out as David hoped? After all, he is not self-sufficient in power. He still gets power bills and the recent addition of a spa pool and EV have significantly boosted his power consumption. It will take a year, featuring winter and summer months before David can evaluate precisely how well his investment is performing.

Though he does say as an indication that a power bill for a recent month was just $60, whereas previously it would have been around the $180 to $230 mark.

The economics improve even further if you are savvy about when you charge the car and use the dishwasher and washing machine – all heavy electricity users. David says as much as possible, do all these things during the day – taking maximum advantage of your solar power generating capacity – rather than in the evening or overnight.

According to David, going solar would be even more attractive, and thereby yield greater environmental benefits, if the Government subsidised householders and businesses to make the transition to solar and thinks this would make more sense than the current policy of subsidising electric cars. He says it would also be better if householders could get more money for the electricity they pump back into the grid. David typically pays 28 cents per kWh to draw from the grid but gets only about 8 cents per kWh when he exports
to the grid.

The first of these points don’t quite wash with the Government’s Energy Efficiency and Conservation Authority (EECA). Spokesperson Dr Gareth Gretton says New Zealand’s electricity system is already highly renewable from using sources such as hydro, geothermal and wind power. This means households switching to solar, though welcome, will likely have a lower impact on greenhouse gas emissions than in other countries.

In New Zealand, such emissions would be more effectively reduced by people switching to an electric or fuel-efficient vehicle, thereby bolstering the case for subsidising electric cars.

“More than 48 per cent of New Zealand’s energy-related greenhouse gas emissions come from transport,” he says.
Mahurangi Matters also approached the Electricity Authority – which regulates the New Zealand electricity market – to see if it thought there was scope for householders getting more money for the power they generate but did not get a reply before going to press. But a check on the Trustpower website perhaps points to the likely answer.

Trustpower explains the money it pays out to householders generating electricity is lower than what it retails it for, to cover the cost of things such as lines and operating margins.

Nevertheless, these caveats are unlikely to temper David’s enthusiasm for solar given he is already reaping tangible benefits from a source with a secure future.

“After all, the sun is going to keep shining, short of a nuclear war,” he says.