West facing solar panels
There was a bit of a fuss on the US web late last year about whether solar panels should face south (that is, towards the path of the sun) or west (towards the setting sun). One point that emerged is that, while the electricity generated by west facing panels during the afternoon peak is more valuable, that isn’t reflected in the prices paid by consumers.
But thinking about the situation for new installations in Queensland, and particularly North Queensland, the case for facing west looks strong. The first thing to observe is that, in the tropics, the sun is in the south in summer and the north in winter, so there’s not a lot of benefit in choosing one or the other.
Second, Ergon now has a “time of use” tariff, to be used in conjunction with a “PeakSmart” airconditioner, which has a peak rate of 34c/kwh between 4 and 8 pm on weekdays. That’s almost as good as the 44c feed-in tariff that used to be on offer, and massively better than the 8c rate available to new installations. Even the shoulder rate of 24c is way above the feed-in tariff So, if you are installing panels, you really want to maximize your own consumption and minimise the amount fed back to the grid.
My first cut at a calculation suggests that, with this tariff, solar PV looks pretty good. Assume a cost of $2/watt installed, which is common for large systems, and suppose that, with the western orientation you get 1000 hours a year, equally divided between shoulder and peak. That is, each installed watt of capacity saves you 1 kwH/year, at around 30 c/kwh, for a 15 per cent rate of return. Even if you add back the 70c/watt or so saved by virtue of renewable energy credits, the return is still above 10 per cent.
Feel free to point out arithmetic or parameter errors here.