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Comment by david422 | Hacker News Reader

I just got solar panels. I was crunching the numbers and it's a long payback. I am really waiting to see how it turns out.

Currently, the days are very short - 9 hours of sunlight. It's been cloudy and/or snowy quite a few days - which means zero production. Partly cloudy also drops production significantly.

On a good day we might generate 25-30kWh of electricity. But that is also approximately what we use. I'm hoping that during different seasons we will have higher production and/or more days of the week generating.

Because otherwise, our electric bill every month is not a huge part of our expenditures, and we've paid a large upfront cost to (currently) only reduce that by a portion.

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I got a 2.4kw array on my smallish roof in London. I was tracking payback at ~24 years but all of a sudden I'm paying 25p/kwh instead of 12p/kwh, which means my payback is considerably shorter!

Yup. I did a very quick calculation based on last years yield and if the new energy prizes remain at this level it seems our 2.7kWp is going to pay itself back in about 4 years (!) instead of about 9-10 years. Crazy.

You might have spent too much on the array. Most people target a 10-15 year payback period. But benchmarking it on December/January production is also likely to blow up your projections as you noted.

If you're net zero in the middle of winter you're probably going to be positive in the summer unless you live in a very hot climate. IMHO sizing an array to be net positive over the course of a year is probably a mistake, as this draws the ire of your power company and they'll probably screw you on overproduction. If you're planning to buy an electric car or something in the near future then it might not be a problem, but generally the best plan is to buy for about 100% of your total yearly usage. Solar panel production typically decreases by 2% during the first year of operation (0.5% every subsequent year) so you'll be slightly net negative which keeps you on good terms with the power company.

One nice thing with the panels is that they effectively lock in your power rate at whatever you paid. You won't get burned by ever increasing power rates. It's a hedge against future rate hikes.

> If you're net zero in the middle of winter

Only net zero on good days. And so far there have been plenty of bad days.

I would love to have gotten more because I'd like to add an electric car as well as some heat pumps. But my roof is only so big.

I didn't know that about the power companies being unhappy though.

For us the payback is about 3.5-4 years depending on how much I use myself and how much I sell back on the grid. Granted, I got the panels at a discount.

I also recently got solar panels, they were calculated to provide more then my household consumes year-round, and should pay themselves back in 6-7 years based on 2021 energy prices and regulations. I anticipate having to get an electric car to use up all that energy :-)

One thing the author missed is that in the Netherlands you can re-claim the VAT paid on the solar installation, saving 21% of costs. Probably not worth the effort for a very small installation, but for a bigger one it saves considerably.

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