Harry Austin

With the price of electricity likely to go up and trying to reduce greenhouse gases, being a “solar nerd” is great.

Back in May 2020, I had my first set of solar panels (4.725 kilowatt with a 9.5 kilowatt per hour battery) installed.

These are attached to the lighting and power point circuit because when we had our house built, a work colleague, who is an electrician, recommended we bring in three phases with the option of having a three-phase connection in the garage should I want to run three-phase machinery. It would also help to balance the draw from the grid.

Since then, we have bought an electric car, which I try to charge off the roof solar rather than selling back to the grid. Sell to the grid at 8.5 cents and buy it back later at 30c a kWh.

So, I like to say I am driving on sunshine. Of the 49,000 kilometres we have driven in the car, at least 40,000km would have been powered by the solar panels.

I purchased four 500-watt solar panels and a 3Kw inverter for an idea I had and put them up on future posts.

This year, I have erected them on my garage roof and had them connected into the grid via the cooking circuit.

In the 28 days since connection, they have generated 180kWh. Now we are in winter, so I expect that in summer this figure will double.

I have room on my garage to put another eight or 12 of these panels, and I would put in a battery storage system at the same time.

If you look up on the internet on alibaba.com, the cost of solar panels is from 8 cents US a watt to 20 cents US a watt. That equates to NZ$ 122 -304 a Kw of panels.

I also looked at a hybrid inverter with 50 kWh battery, which was NZ$4350. Note, you need to check that inverters are compliant with your local lines company and comply with AU/NZ standards before you buy.

Remember, also, there are shipping costs and possible import duties and tax, and you need to pick them up from port of delivery.

Here in the Bay of Plenty with lots of sunshine hours, solar makes sense. So, I would suggest if you’re able to, you should put as many solar panels on your roof as possible with battery storage so you can use the power you make and have stored overnight.

If you have an EV, you can trickle charge (1.6kWh) it overnight so you would need 30-50kWh battery. My best June winter day generation was about 18.1kWh. The best January summer generation, 36,9kWh (2024).

In July, I made 380kWh. I sold 43.7kWh, I bought 228.7 kWh, and I used 510kWh on the lighting and power point circuit on which I charged my EV for 18 days while the sun shone and I ran the heat pumps on 27 of those days, in the evenings and overnight.

Even with a full 9.5kwh battery, the heat pump will empty overnight, and I buy power. I have a well-insulated house and it’s been retrofitted double glazed and it’s all electric.