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> We were probably spending nearly $10,000 on electricity a year across the business and home,” he said. “We worked out we could do a large solar system which c
by danans 4y ago
> We were probably spending nearly $10,000 on electricity a year across the business and home,” he said. “We worked out we could do a large solar system which could deliver that 200-amp feed, be able to pay itself off and be off the grid.”
$220K to offset a $10k/yr electric bill is a 22 year payback period, which is quite a long time if you are using energy bills as a rationale.
The primary rationalization for storage when you have grid access already is grid backup, and the secondary rationalization is for energy price arbitrage. Backup is hard to value monetarily because it depends on how much not having electricity costs you. Arbitrage is easy to value, but doesn't pay back much unless you have extremely variable retail electric rates.
> “The most confusing and contentious point for me is that Tesla seems to express that the off-grid Powerwalls cannot guarantee 100 per cent uptime … [but] this was never expressed to me during deployment, and had I known this, I would not have embarked on this journey.”
For a $220k installation maybe they wouldn't have been incentivized to explain it. One mode of the grid behaves a bit like insurance, increasing reliability and masking variability. Going off grid when you have the option to stay on seems like an irrational choice.
- shalmanese 4y agoBut $150K of it was subsidized so it's only a 7 year payback period.
- danans 4y agoAccording to the article, the $150k was a loan, not subsidized. They have to pay it back.
- Someone 4y agoNot subsidized, loaned. FTA: “Of that, $150,000 was from a South Australian government-backed solar loan, with another $70,000 in cash.” There might be some subsidy in getting an attractive interest rate, but AFAICT, the article doesn’t say anything about that.
- hinkley 4y agoThere is something to be said both financially and emotionally about getting your operating costs to be lower. And making a big capex expenditure in a year when you saw a windfall of money would flatten out your tax burden. Of course here it’s not that simple because you’ll be replacing worn equipment at some point and you will have to spin proverbial plates to keep that working well. I suspect this is about 3 parts financially sound and 2 parts Captain Ahab if you look at the full math.
- danans 4y ago> There is something to be said both financially and emotionally about getting your operating costs to be lower. I agree. I have a battery backup system too for similar reasons. However, I think that the operating cost savings start diminishing pretty quickly when you have to size a system to go completely off grid and simultaneously can't tolerate a higher outage rate. That said, if you take the customers word, it sounds like Tesla Solar gave them the impression that they would have 100% off grid up time and didn't deliver on that due to their own inadequate equipment.