Going solar – David, ten years on

I recently received an unexpected email from David, who was good enough to write about his rooftop solar power installation for Green Path ten years ago:

As I was cleaning out our filing cabinet (yes, still have one of those!) I found all of our power bills back from when we first had solar installed. I crunched the numbers out of curiosity and found that in solar credits, we saved $7594 over the last 10+ years. This doesn’t include the offsetting of power (e.g. using the power off the roof during the day); that’s about $3000 worth. Given our 1.5 kW solar panels were only $3300 at the time, that’s not a bad return.

Whether the panels have actually done anything to help the environment or lessen our dependency on coal remains to be seen, but at least our panels are still functioning pretty well even after all this time and nothing has needed repair or replacement. Our daily output is down to about 7.5 kWh on average, down from 8-10 kWh at its peak originally, but we’re still covering our consumption and costs, and have only paid a few dollars (less than $100) out of pocket over the last decade.

I replied, of course, thanking him for the update and asking whether I could post it here. I mentioned his one-year report for context. As I said, it suggests that his panels are performing just as well as they did a decade ago. The conversation continued…

It’s good to re-read what was happening back in 2011 and see that my calculations then have proven true. Our power usage really hasn’t changed since then; we’ve added a few smart devices and we’ve noticed a big difference with COVID and working from home, but it’s still pretty much as it was.

We’re not really concerned with when we use power now, knowing that our solar will cover our usage. In fact, I now prefer to use devices during the day, to use the solar power rather than to rely on the coal grid, which is a change from my 2011 financial focus.

We ourselves sold our house a few years ago, as you know, so we lost the 44c feed-in tariff, which was a bit sad. On the other hand, that system had more than paid for itself by then and the new one at our present house was so much cheaper that the pay-back time will actually be comparable.

That post is a great read – your experiences and reflections match ours. The only thing we did differently is that due to the size of our house and configuration of pipework, we chose to swap our gas hot water system for a roof-mounted solar tank rather than a ground-based heat-pump.

The cost of the system and installation (a 300L, dual-panel system) was about $5000 and we knew it was unlikely we’d get a great return on investment but it should have lasted 10+ years. … Anyway, we’re fortunate that our 44c feed-in tariff continues, but when it ends we’ll probably look at upgrading our solar and considering an EV and battery storage. Interesting times ahead!

I suspect that David and I are among a whole cohort of early adopters who have had ten years of positive experience with rooftop solar, and will be keen to extend it to batteries and vehicles whenever the opportunities arise. The time-frame for that is still not clear but it is likely to be less than five years.

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