I have a modest set of solar panels on an entirely ordinary house in suburban London. On average they generate about 3,800kWh per year. We also use about 3,800kWh of electricity each year. Obviously, we can't use all the power produced over summer and we need to buy power in winter. So here's my question: How big a battery would we need in order to be completely self-sufficient? Background …
We pay a daily lines maintenance charge of 60c, then 29c/kWh during the day and a little under 27c for off peak night time. Then add 15% tax to these. These are in NZD, so almost halve them to get USD (e.g. 60cNZD is 35cUSD)
We also get about 17.5c for each kWh sold to the grid. So to sell it in the day and buy back at night is a 10c additional cost. A 10kWh battery can save a max of $1 per night, meaning it’s really hard to make your money back on a battery that’s $10-15k NZD on it’s own.
We have a national grid that is shared by all power companies, and is open to all. Power companies just buy and sell power on the grid based on a spot pricing system. Because of this, we have very easy movement between power companies, and have dozens to choose from, leading to a lot of competition. Mine is a tiny company that specialises in solar, having sell to grid rates well above most companies.
The company that did our solar install had their top recommended companies, they worked out the best for us, and organised getting set up with them. Was I pretty nice experience to have everything taken care of like that!
I’m paying 50c per kWh for grid…its bad. And that’s if I don’t go over the limit. There’s 4 teirs so it gets more expensive per tier.
Wait, it gets more expensive when you use more?
Exceptionally. Yes.
What an odd pricing structure! I would normally expect higher usage to mean lower prices per unit.
I guess that gives you a large incentive to have at least a little solar, as there would be a big financial benefit.
Its pretty bad. They only show a couple of the tiers here. https://www.pge.com/assets/pge/docs/account/rate-plans/residential-electric-rate-plan-pricing.pdf
This is an old pdf but the only one they have on the website. They haven’t updated it in a while so its not counting the latest 2 rate increases.
Interesting! Your power seems super expensive.
We pay a daily lines maintenance charge of 60c, then 29c/kWh during the day and a little under 27c for off peak night time. Then add 15% tax to these. These are in NZD, so almost halve them to get USD (e.g. 60cNZD is 35cUSD)
We also get about 17.5c for each kWh sold to the grid. So to sell it in the day and buy back at night is a 10c additional cost. A 10kWh battery can save a max of $1 per night, meaning it’s really hard to make your money back on a battery that’s $10-15k NZD on it’s own.
4 years ago it was 18c per kwh. Which was nice.
Yours is very good. and selling back to the grid would be nice! Making me jealous lol.
I’m feeling very lucky now!
We have a national grid that is shared by all power companies, and is open to all. Power companies just buy and sell power on the grid based on a spot pricing system. Because of this, we have very easy movement between power companies, and have dozens to choose from, leading to a lot of competition. Mine is a tiny company that specialises in solar, having sell to grid rates well above most companies.
The company that did our solar install had their top recommended companies, they worked out the best for us, and organised getting set up with them. Was I pretty nice experience to have everything taken care of like that!