We had solar panels installed yesterday, and today I had a phone call from someone who was supposed to contact us 4 weeks ago to provide a quote!
Why’d you do that? You should’ve waited until after the eclipse! Now you won’t get your money’s worth!
Just before I left I contacted a few mobs about a battery. They all responded but would only discuss panels, no matter how specific I got.
I wouldn't have a battery anywhere close to my house. High energy densities are asking for fires; Strapping a battery to your house is a daft as strapping jerry cans full of petrol to it.
Sure, it
probably won't burn the place to the ground, if nothing goes wrong. But then, it probably won't pay for itself within its safe working lifespan, either - and in a couple of decades, the 'burbs will be full of tired old batteries that people haven't maintained properly. It's a recipe for disaster.
My brother attached a battery to his solar panel system. The battery cost ten grand. I don't see how that will ever bring a return on the investment.
Our system cost $10k, and we figure it will pay for itself in around 3 - 4 years given our current electricity consumption.
Yeah, but that's because we will mostly
use the electricity generated by the system, in real time.
If our consumption pattern was more typical, we would have a
much longer ROI; But buying an expensive battery would do little to help - and might even make things worse.
In our case, we plan to do very little overproduction, so a battery would never get charged - unless we bought even more panels.
Here's our generation and consumption for yesterday, which was a lovely sunnly day with just a few small clouds in the afternoon:
Very few households use 40+ kWh/day; And even fewer have a demand curve that is so closely matched to the insolation curve.
I suspected that our demand would be a fair match for insolation, but I am pleasantly surprised at just how well it fits.
Without solar, our bill for yesterday would be 47.61kWh at 31.724c/kWh, for a total of $15.10
With solar, it will be 12.02kWh at 31.724c/kWh for a subtotal of $3.81, plus a feed-in of 15.82kWh at -5c/kWh, for a subtotal of -$0.79; That's a final total of $3.02, or a saving of $12.08 which can go towards the capital cost of the system.
That gives an 837 day ROI (ignoring the cost of capital, and the fixed connection charges), which is about two years and three months; But capital isn't free, so there's about another 180 days to pay the interest, for a total ROI of closer to two years and ten months.
BUT - yesterday was a particularly sunny day. Not every day is that sunny, even in Brisbane. Hence 3-4 years ROI, as a guesstimate. It depends on how sunny it is, and on our ongoing power usage continuing to match the pattern of insolation.
Without storage, we save ~$12/day (on a good day); With storage, we could maybe save a further ~$4, but saving that extra $4 comes at the expense of
doubling the initial capital cost.
The solar system pays for itself in about 4 years; The battery would take around 12 years (it costs about the same, but saves only a third of the dollars) - which is pretty much the lifespan of a modern household battery system. So by the time it pays for itself, it needs replacing.