What a year of solar and batteries saved us in 2025 • Hacker News Board

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

#201

Post by order-matters » Tue, Jan 13, 2026, 6:33 PM UTC

vasco wrote: post #51

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…

Almost all simulations I've done across 3 countries with 3 different payback models for selling back to grid (one of the three doesn’t allow selling back almost anything above your consumption), I could never make investing in Solar not being a gamble. You really need to gamble on odds of replacing equipment being very low for it to make sense. And in practice most people I anecdotally know that run it, after 5-7 yea…

im a systems engineer and cost analyst who has put together some modeling myself as well. as a personal investment on your house, i agree. The economic value of solar seems to be best applied as neighborhood or block purchases, like as part of a co-op or hoa. they would need dedicated infrastructure like a communal parking lot with solar overhead, or running them on the property line borders with an easement underneath for servicing, using property fencing as main support (with upgraded fencing)

basically, the way it really makes sense (to me) is to integrate it as part of a micro-grid system, possibly with generator backups and everything to also keep the lights on in the entire neighborhood if the main grid goes down.

its a higher upfront cost on paper, but way less variables with the roof and you are grouping multiple peoples needs together so the gamble goes down on repairs. the poles for ground-mounting can be used for 40 - 60 years, so you would get multiple panels out of them

probably a bureaucratic nightmare though

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

#202

Post by ishtanbul » Tue, Jan 13, 2026, 6:34 PM UTC

Ensorceled wrote: post #138

kccqzy wrote: post #128

Earlier quoted context omitted.

What breaks in 11 years? Solar panels and batteries both last longer than that. As for your other point of becoming obsolete, why care about chasing latest fads for home appliances.

Are you sure? Lots of people are telling me that batteries only last 4-5 years tops and solar panels usually burn out before 10 years /s I particularly love when they are telling me that my 11 year old Prius' batteries will only last 5 years before they are junk.

This is totally wrong. I work in the industry. Solar panels should last for 30 years, but they degrade in capacity by 0.5 to 1% per year, depending on environmental conditions (temp, radiation, etc). Lithium batteries from tier 1 suppliers can last at least a decade of regular use. It depends on how their cycling and state of charge is managed. If you keep them between 20% and 80% charge, they can last incredibly long.

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

#203

Post by bradphipps » Tue, Jan 13, 2026, 6:40 PM UTC

dlisboa wrote: post #179

It's crazy how power hungry UK homes are, or maybe it's UK power consumption habits in general. I use about ~300 kWh/month. A little bit more with AC some times of the year. What are you even powering with 15000 kWh?

They explain in the article.

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

#204

Post by thechao » Tue, Jan 13, 2026, 6:41 PM UTC

lotsofpulp wrote: post #196

thechao wrote: post #136

Earlier quoted context omitted.

> which would probably hae been another 3-5k if I could have found someone to do it. Yo. If you can find an electrician to stop by my house and turn a light switch off for less than 1000$, please inform me. I got a quote for 25k$ to install a system that size, and that price. City code has me by the balls: I can't modify my main panel without inspection, the inspector won't show up without a licensed electrician, and…

Run for political office espousing Texas' famous "freedom" that does not allow you to modify your own home.

"Freedom for me, rules for thee". Texas has always been a cesspit of political kickback. I mean ... not Illinois or New Jersey, but annoying enough.

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

#205

Post by GordonS » Tue, Jan 13, 2026, 6:42 PM UTC

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.

I was really surprised too - our family (with electric car and a lot of tech) uses only a third of the energy used in TFA!

Still, even with our lower usage, solar still makes sense (especially with a South-facing roof) because electricity is so damned expensive in the UK :(

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

#206

Post by Aperocky » Tue, Jan 13, 2026, 6:46 PM UTC

systemtest wrote: post #98

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.

Is the disconnect automatic? what happens when you're not connected to the grid but battery is full?

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

#207

Post by mikaeluman » Tue, Jan 13, 2026, 6:52 PM UTC

epistasis wrote: post #149

mikaeluman wrote: post #137

This is indeed nice for a well-to-do home. But there is a tragedy of the commons issue here. The grid needs to be up 24/7. And while peak usage is just that, the grid capacity still needs to support peak usage. This can theoretically be done using batteries but not for an extended amount of time. To say we can have batteries for 2 weeks of normal consumption is highly improbable. The metals do build those batteries d…

Residential solar with batteries greatly aids the grid and reduces costs for the entire system. > The metals do build those batteries do not exist. Or put in a worse way, the mines do not exist. Lithium and sodium, the two most promising battery metals, are not usually mined, though in Australia I hear there is mining. It's more of a brine process. All across the US, frackers are finding that all that water they are…

I don't agree. Lithium and Copper are mined and given electrification scenarios there is a projected supply deficit: https://www.iea.org/reports/global-critical-minerals-outlook...

Those prices are outdated now since practically all metals are surging.

There has indeed been great growth in battery capacity but it's as I said nowhere near able to supply a country like Sweden during the winter. It is off by orders of magnitude. We need 5TWh for that. It is not going to happen any time soon.

I understand California is different. Still, one would need to do these risk scenario calculations. Have they been made?

I know California has rotating blackouts already as it is. I really don't have any idea how people find that acceptable. If it happened in Sweden the government would be replaced on the day. It would be a real disaster.

I will be a bigger believer if a state like California can actually show its possible.

For sure I hope technology improves but the current ideas of solar+battery are simply highly unlikely.

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

#208

Post by GordonS » Tue, Jan 13, 2026, 6:53 PM UTC

dlisboa wrote: post #179

It's crazy how power hungry UK homes are, or maybe it's UK power consumption habits in general. I use about ~300 kWh/month. A little bit more with AC some times of the year. What are you even powering with 15000 kWh?

The OP is a significant outlier - the UK average is around 7.4kWh/household/day[0], or 11.2kWh specifically for large households.

[0] https://www.britishgas.co.uk/energy/guides/average-bill.html

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

#209

Post by mikaeluman » Tue, Jan 13, 2026, 6:54 PM UTC

ImPostingOnHN wrote: post #153

mikaeluman wrote: post #137

This is indeed nice for a well-to-do home. But there is a tragedy of the commons issue here. The grid needs to be up 24/7. And while peak usage is just that, the grid capacity still needs to support peak usage. This can theoretically be done using batteries but not for an extended amount of time. To say we can have batteries for 2 weeks of normal consumption is highly improbable. The metals do build those batteries d…

What makes you think I need batteries for 2 weeks of normal consumption?

We practically don't see the sun in northern Europe during winter. And yes, the wind might not blow either.

I consider 2 weeks of supply a bare minimum.

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

#210

Post by fennecbutt » Tue, Jan 13, 2026, 6:55 PM UTC

fartfeatures wrote: post #168

barbazoo wrote: post #160

Earlier quoted context omitted.

Probably because the economics just don't make sense here. You'd have to have so many compatible cars on the road, driving all day with no opportunity to charge. I'm having a hard time imagining a place I've been to in North America where that'd seem logical. > they are doing that in China Are they actually doing that at scale?

A little out of date now but: > As of June 2024, Nio had installed 2,432 power swap stations in China, including 804 along highways, representing the largest battery swapping network in the country. Nio aims to expand to 4,000 stations globally by 2025. By February 2025, Nio had 3,106 battery swap stations in China, with 964 located along highways. In January 2025 alone, Nio added 111 swap stations and provided 2,949…

From the country that brought you mass wastage of bicycles, now we get battery swapping.

This is pretty much just a "gamble by deploying as quickly as possible making our system the standard if it catches on" type of investment.