Re: Grand Apagon - Electricity (not) in Spain

On 30/04/2025 8:41 pm, Jeff Layman wrote:

On 30/04/2025 08:05, Bill Sloman wrote:
 

About 40% of new roof-top solar power installations in Australia include
a Tesla Powerwall (or something similar) to keep the lights on at night.
>
It adds appreciably to the capital cost, but pays for itself in a couple
of years. Australia's feed-in tariffs aren't generous.

 Over here in the UK a 13.5kWh Tesla 3 powerwall will cost around £10k (includes installation). This (USA) site suggests a payback time of 14 years <https://www.solarreviews.com/blog/is-the-tesla-powerwall-the-best-solar-battery-available#is-the-tesla-powerwall-worth-the-price?>.
 This Australian site <https://cleannrg.com.au/the-real-cost-of-teslas-powerwall-battery-storage/> seems to suggest that a powerwall save A$3000 a year, but the initial cost is A$20000. Doesn't that make the payback time 6 - 7 years rather than just a couple?

Strictly speaking it's the pay-off time for the battery on it's own which is the issue. Roof-top solar is a popular investment, but on your figures at takes about three years to pay for itself.
Adding the battery is a separate investment which cuts your power bills a lot more, and the time to pay off just the battery is about five years - on those numbers. You pay off your solar cells and their inverter system quite a lot faster too. Without the battery it takes about three years, with the battery an additional 20 months.
I suppose it also depends on the battery you use. The Chinese BYD Blade battery seems to be better than it's Tesla equivalent. Whether a BYD powerwall could be cheaper than it's Tesla equivalent is anybody's guess.
https://en.wikipedia.org/wiki/BYD_Blade_battery
I was just quoting some local newspaper articles. Adding the battery to your roof-top solar does seem to be surprisingly popular here.
--
Bill Sloman, Sydney