Friday, 16 June 2017

Powering up

How most of us power our homes and businesses is on the cusp of change. 

When we first built our house, we put in photovoltaic cells on the roof to cover our generation requirements over the summer months, with the infrastructure to double the capacity later on, if we felt the need to.

However, batteries at that point were going to cost us another $15k, so we decided to go with a grid-tie system, where we sold our micro-generation into the grid, then drew back what we needed. Batteries at that time were also very, very heavy, and only lasted ten years. It seemed like a great idea.

We signed up with the only electricity company in New Zealand who was paying for micro-generation at that time - Meridian - and we got a 'one for one' contract. What we generated, we got free back out of the grid. Our first couple of years were neutral, as our summer power generation was more than we needed, so also covered our supply charge.

Then the prices paid started to shift down. And down. After seven years, now we pay $0.28 per unit used, and receive only $0.08 per unit we generate. We reorganised our internal system so that during the day we use our own generation ourselves before feeding it into the grid - otherwise we would be giving Meridian $0.20 for every unit we generate. Despite this, our power bills now cost us between $70 to 80 per month.

So I am watching what is happening in the US with Tesla with great interest. The Tesla Powerwall only costs around $7k per battery. Better still, the technology has been vastly improved with the Powerwall 2, which has the added advantage of a built in inverter, and landed in New Zealand with New Zealand taxes paid. While the cost is one and half times the first version at $11k, it looks like this one battery will have enough capacity for our house to be permanently - and easily - off-grid.

Vector in New Zealand has the commercial licence for Tesla Powerwall. I'm keen.



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