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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

#91

Post by domh »

> The batteries can fill up on the off-peak rate overnight at £0.07/kWh, and then export it during the peak rate for £0.15/kWh, meaning any excess solar production or battery capacity can be exported for a reasonable amount.

Honestly I didn't know this was allowed.

I recently got a heat pump and am on a time-of-use tariff (https://octopus.energy/smart/cosy-octopus/) and have been thinking about pulling the plug on battery storage for a similar purpose (charge during the cheap hours; run the house off battery during the day). I am currently using between 40-50kWh per day - anyone have similar usage to this and can recommend batteries for this?

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

#92

Post by dns_snek »

mbesto wrote: post #52

It's wild how overpriced Tesla Powerwalls are. 16 kWh battery with all of the UL supported listings etc = $3300 [0] 13.5 kWh Tesla Powerwall is $12k~$15k You would get your return way back quicker. [0] - https://www.ruixubattery.com/product-page/lithi2-16-battery-... EDIT: As others have pointed out, powerwalls have inverters built in so it's not totally apples to apples. You can get a beefy inverter for $5k and it's…

You're comparing the cost of a battery with a full system. That 16 kWh battery requires a ~$3000 inverter to go along with it.

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

#93

Post by jstsch »

tomashubelbauer wrote: post #53
Barbing wrote: post #41

Earlier quoted context omitted.

Awesome. Feel you have more unknowns on the safety front? vs. the expensive off-the-shelf. [in the USA, it’d also be “fewer names to sue” in that unlikely tragedy of combustion in home, but no euro /kWh targets there]

LFP batteries are as likely to burn down your house as a stack of wood is. I'd be worried about the inverter or botched DIY wiring (especially not to spec torque on terminal connections and botched crimps leading to hot spots), but not about the batteries themselves. For a person who wants to save some money, but doesn't know how to work with electricity, the best move is probably to get cheap LFP cells from China, b…

> especially not to spec torque on terminal connections and botched crimps leading to hot spots

This was indeed my greatest concern. However the battery came with pre-crimped very solid DC wires, and nice push connectors for the battery itself. The battery also has an integrated DC breaker (great!).

The system runs 3KW max, so I just added an additional breaker (with RCD integrated) in the conduit box. In NL this is something a DIY-home owner easily can do themselves :) (just use the right solid/flex stranded cabling for the connectors, etc...)

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

#94

Post by Dylan1312 »

UltraSane wrote: post #68
bz_bz_bz wrote: post #22

Earlier quoted context omitted.

Their total household usage was actually ~17.3 MWh depending on what data source you're using for their usage. Given 6 MWh of exports with only 3.2 MWh of total solar production, they are cycling their powerwall to get paid for the fact that their off-peak rate is half the price of their peak export tariff rate which is inflating the number you're looking at.

That is still an enormous amount of electricity for a single family to consume.

It's less than 50kwh a day, high but seems reasonable with 2 electric cars.

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

#95

Post by doikor »

lm28469 wrote: post #44
BeetleB wrote: post #42

Earlier quoted context omitted.

Who spends $50K on heat pumps? They're not anywhere near that expensive.

I'm talking about geothermal water/water installs for central heating. No one is heating their place with air/air heat pumps besides americans who haven't figured out that heating spaces via air is shit tier in term of comfort and efficiency

> No one is heating their place with air/air heat pumps besides americans who haven't figured out that heating spaces via air is shit tier in term of comfort and efficiency

At least here in Finland a lot of people do. Very popular choice when replacing old oil furnaces (and as a "replacement" for direct electric heating offcourse)

Geothermal heatpump is something people mostly think about when building new.

Air heatpumps with the inside unit start from around 1000€ and 300€ to 500€ for the install. The price is mainly based on the size of the house (and in big houses you will need multiple or one with multiple inside units)

A fireplace for the couple really cold weeks to cut down the electricity bills are popular but people had those even before the air heatpumps so nothing new really.

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

#96

Post by thescriptkiddie »

systemtest wrote: post #90
boringg wrote: post #34

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…

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battery life span is defined as when the reach 80% of their original capacity. it's possible that the decline will accelerate after that point but they aren't suddenly useless

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

#97

Post by toomuchtodo »

systemtest wrote: post #90
boringg wrote: post #34

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…

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https://electrek.co/2026/01/06/catl-ev-batteries-significant...

> For example, CATL is one of four LFP battery suppliers at the Zhangbei National Wind-Solar-Storage Demonstration Project in China. CATL’s batteries are the only ones that have never been replaced, retaining over 90% of residual capacity after 14 years.

Batteries are not only not worthless after almost 15 years in service, they still have sufficient capacity to continue to operate. If you need that capacity back lost to degradation, add a battery ~15 years from now, they will only continue to get cheaper.

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

#98

Post by systemtest »

dlcarrier wrote: post #67

Where I am in California, there's a $30+/mo charge to connect to the grid, and the largest savings from a battery was being able to disconnect from the grid. There's lots of time I have excess power generation when I could give to the power grid, if I were connected, but I would have to pay extra to do so, so the potential goes unused.

Is delivering back to the grid economical in California? Where I'm from people disconnect solar panels on sunny days because it costs them money to return to the grid.

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

#100

Post by ZeroGravitas »

pjc50 wrote: post #40
lm28469 wrote: post #27

Earlier quoted context omitted.

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.

UK government subsidy support for air-to-air was announced a couple of months ago:

https://www.gov.uk/government/news/discounts-for-families-to...

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