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What a year of solar and batteries saved us in 2025

scotthelme.co.uk

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Re: What a year of solar and batteries saved us in 2025

#31

Post by rokkamokka »

lm28469 wrote: post #27
kccqzy wrote: post #2

Good analysis. And kudos to the author for saving money. But still 21.6MWh per year excluding solar production seems too high for a household. I use electric heating and drive an electric vehicle, and my household annual energy consumption is about one fifth of that.

It's high but it really depends on your lifestyle and appliances. If you have a heat pump water heater and heat pump based floor heating you'll use 1/4th of the energy as the same house with resistive water/floor heating. A house which barely passed regulation from 2010 will consume 5-10x the energy of a certified passive house. etc. That being said I think you have to draw the line somewhere. I'd much rather have in…

Heatpumps are not a gimmick - they're an excellent technology with lots of efficient and effective uses :)

Re: What a year of solar and batteries saved us in 2025

#32

Post by cptcobalt »

elAhmo wrote: post #25

Great read! I am just wondering would stacking up batteries, charging them off-peak and using/selling back during peak usage be as good as this, or even better? Seems like this shouldn't be a viable scenario, but given the prices and idle capacity, it seems just investing in batteries and charging them at night, to be used/sold to the grid during the day would be as good as a solar installation.

You can usually save more by generating solar locally and using it to power the home and charge the battery, then discharging the battery during peak hours (usually around and just after sunset) to earn the most. Obviously higher upfront capex.

Pure grid cycling is also frowned on by some utilities.

Re: What a year of solar and batteries saved us in 2025

#34

Post by boringg »

9-11 year payback isn't bad based on the projections. You could probably goose it a bit with inflation of electrical prices (depends on how the electrical policies change and what they pass through).

I'll also add theres some O&M coming down the line. Inverters @ year 10, small maintenance and Im assuming you re-did your roof before you installed. Anyone putting solar up make sure you do it at the same time as a roof because taking it down to redo a roof kills your economic value.

Re: What a year of solar and batteries saved us in 2025

#35

Post by lm28469 »

flakeoil wrote: post #21
lm28469 wrote: post #10

Why do people still go for tesla powerwalls when you can get BYD batteries with 70%+ more capacity for cheaper ? You can buy a BYD HVM 22.1 kWh for 6000 euros now (£5200) vs powerwall 2 13.5kwh for 7000 euros.

Or you can by a car instead. An MG4 costs less than 20000 euros with a 51kWh LFP battery. In addition to a good battery, it's a great car as well.

afaik it doesn't support bidirectional charging, I'd much rather cycle my standalone lifepo4 bank than my EV battery

Re: What a year of solar and batteries saved us in 2025

#36

Post by nasmorn »

So what I take away is that he is using approx 3x electricity, that I do and that is including my electric car. I use an additional 5-7MWh of heat but on a heat pump that would still only be a max of 2MWh which doesn’t even bring me to half of his usage, for a family of 4.

Re: What a year of solar and batteries saved us in 2025

#37

Post by pixl97 »

elAhmo wrote: post #25

Great read! I am just wondering would stacking up batteries, charging them off-peak and using/selling back during peak usage be as good as this, or even better? Seems like this shouldn't be a viable scenario, but given the prices and idle capacity, it seems just investing in batteries and charging them at night, to be used/sold to the grid during the day would be as good as a solar installation.

>it seems just investing in batteries and charging

I mean a lot of companies already do this with megawatt/gigawatt installations.

The key is peaking and grid stabilization. If you're a huge provider you can pay for all your batteries in a year or two if there is some large grid emergency and rates skyrocket.

If you're a non-commercial user, it's going to be hard because the provider rates you pay/get paid are much more likely to be fixed at a pretty low rate.

Re: What a year of solar and batteries saved us in 2025

#38

Post by DamonHD »

cptcobalt wrote: post #32
elAhmo wrote: post #25

Great read! I am just wondering would stacking up batteries, charging them off-peak and using/selling back during peak usage be as good as this, or even better? Seems like this shouldn't be a viable scenario, but given the prices and idle capacity, it seems just investing in batteries and charging them at night, to be used/sold to the grid during the day would be as good as a solar installation.

You can usually save more by generating solar locally and using it to power the home and charge the battery, then discharging the battery during peak hours (usually around and just after sunset) to earn the most. Obviously higher upfront capex. Pure grid cycling is also frowned on by some utilities.

Octopus in the UK has tariffs where it basically takes over your system (ie the batteries in particular) and subsumes them into its wider activities, eg:

https://octopus.energy/intelligent-flux-faqs/

Re: What a year of solar and batteries saved us in 2025

#39

Post by f1shy »

jstsch wrote: post #12

Battery prices are getting really low, if you're willing to do some DIY. Just received a 15kWh battery from China. A 'Humsienk'. Combined it with a GroWatt SPA3000TL-BL inverter. Total price, 1600 euros. So close to the magical 100 euros per kWh. Driving it with some interesting combinations of Raspberry PI's and serial interfaces and custom written Go code, but it works... :)

> Battery prices are getting really low, if you're willing to do some DIY.

Willing and allowed. In some countries it can only be done by certified electricians.

Re: What a year of solar and batteries saved us in 2025

#40

Post by pjc50 »

lm28469 wrote: post #27
kccqzy wrote: post #2

Good analysis. And kudos to the author for saving money. But still 21.6MWh per year excluding solar production seems too high for a household. I use electric heating and drive an electric vehicle, and my household annual energy consumption is about one fifth of that.

It's high but it really depends on your lifestyle and appliances. If you have a heat pump water heater and heat pump based floor heating you'll use 1/4th of the energy as the same house with resistive water/floor heating. A house which barely passed regulation from 2010 will consume 5-10x the energy of a certified passive house. etc. That being said I think you have to draw the line somewhere. I'd much rather have in…

Heatpumps can now be had for less than £10k .. if you don't have to replace your radiators.

I do think more people should consider mini-split reversible AC in the UK, but the subsidy system specifically excludes it.

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