A small solar milestone

Our 1.5 KW solar power system has been sitting peacefully on our roof for eighteen months now, quietly turning sunshine into electricity. Today it will pass a nice round number in its production stats: 4 MWh of generated power.

As I said in my item about the installation process:

… pay-back time for the whole project (PV system and switchboard) looks like being in the 5 – 8 year range. That’s perfectly acceptable in itself … Of course, if the electricity tariff rises (hands up everyone who thinks it is going to fall? No, my hand didn’t go up either), pay-back time will drop accordingly.

Guess what came up in the news a few days ago?

The Queensland Competition Authority (QCA) released its draft determination for 2013/14 power prices on Friday. Households stand to be hit with a 21.4 per cent increase, and small business with a 15.7 per cent rise, from July.

It is, sadly, no great surprise that state LNP and federal Labor blamed each other for the rises although the QCA blamed both, saying (and I’m quoting the same news item), “the state government’s decision to unfreeze power tariffs, and green schemes like the commonwealth carbon price, had caused the rises.” But that isn’t what I wanted to talk about. I was going see what influence the power price rise will have on my household.

In our first year with solar power, the numbers were:

  • Total produced = 2220 kWh (6.1 kWh/day)
  • Total exported to grid = 960 kWh, for $425 income
  • Total PV power used at home = 1260 kWh, for $270 savings
  • Total benefit = $700

If we take the first year as being typical and take the “21.4% increase” to be across the board, the standard domestic tariff will rise from 23.1 to 28 c/KWh, increasing our savings in line 3 from $270 to $420. Our income from exports to the grid will not change, so our total benefit will rise by $150 per year to $850 p.a..

In reality, of course, the benefit will appear as a reduction in the price-rise we would otherwise have copped. Our bills are running at around $1000 p.a. ($1500 p.a. gross, less $480 p.a. from the feed-in tariff) and will presumably go up to about $1300 ($1800 gross less the same $480). If we didn’t have the solar power, our bills (on the same consumption) would already be $1800 p.a. and would increase to $2200.

So far, so good. But I ran my figures past David and he is doing substantially better overall from his system (also 1.5 KW) than we are from ours: we are not paying a lot for our power but Ergon is paying him every quarter instead of asking him to pay them. The cheque is only about $170, but it’s a lot better than a bill!

How does he do it? Only two people in the household instead of three; no swimming pool; no-one home on weekdays, so (by his reckoning) 75% of his solar power goes straight into the grid at 44c/KWh; an unshaded North-facing panel array, as compared to our West-facing array affected by late-afternoon shade; and various smaller differences.

One big similarity: we are both happy with our decision to go solar!

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