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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

#111

Post by syncsynchalt »

domh wrote: post #91

> 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…

It benefits the grid to have people consume extra power when there's an oversupply, store it and give it back when there's undersupply. Why shouldn't it be allowed (even encouraged)?

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

#112

Post by dns_snek »

boringg wrote: post #89
latchkey wrote: post #85

Earlier quoted context omitted.

Having power when your entire neighborhood is off, priceless. [edit: yes, I assume you also get batteries, I know that solar alone doesn't magically power your house.]

Whats funny about that -- is you assume thats the case - but a lot of solar isn't installed to be backup power. With Storage yes, but straight up solar -> no.

It's not the default but you can get it installed that way or get it adapted later (less than ideal if you end up having to replace the inverter).

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

#113

Post by benoliver999 »

ortusdux wrote: post #102
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…

IIRC, the original idea was that they would pull older batteries from circulation when their capacities dipped, and then repurpose them as powerwalls, an application where weight is irrelevant. This was back when they expected the batteries to plateau at ~80% capacity after a few years, and they had battery swapping on the roadmap, so they needed to plan for a future where they had a steady supply of batteries that c…

Electric car battery degradation has been super interesting, in that they are going way further than people thought they might. Jonny Smith on youtube bought a 300k+ mile Tesla and the battery is at like 75% health.

As far as I can tell if your battery isn't air cooled, it can go a very long way

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

#114

Post by alberth »

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…

Wont you need to replace the batteries around Year 10 and then this becomes a wash?

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

#115

Post by scarecrowbob »

f1shy wrote: post #39
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.

I mean, it "can" be done without a certificate.

It "may" not be permitted, but if you live in a collection of shacks in rural Colorado that were themselves -already- completely un-permitted then you might decide that it's best to just do the work yourself.

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

#116

Post by riku_iki »

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.

It probably means that you would contribute less than cost of maintaining your grid connection ($30/mo)

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

#117

Post by hvb2 »

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…

Having done 2 solar installs, one over 10 years and one 6 years, both going strong. Nothing else needed, it just sits there and produces.

So, from my experience, that's not the case. Maybe the people you know keep tweaking because they're enthusiasts like you have with cars.

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

#118

Post by hvb2 »

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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> Large solar farms and neighbourhood batteries operate at a much higher efficiency than domestic installations.

Maybe, but that power is typically generated far from where it's consumed and so you have significant transmission losses.

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

#120

Post by toomuchtodo »

systemtest wrote: post #109
toomuchtodo wrote: post #47

Earlier quoted context omitted.

It is essentially a bond return, with the caveat being that solar PV panels will last 25+ years with some degradation and reduction in output. To your point, the best arrangement (imho) is a standing seam metal roof (40-70 year lifetime) with the panels mounted via friction racking with no roof deck penetrations. This avoids the economic cost of pulling everything off the roof to re-roof, and should outlive any homeo…

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This is factually inaccurate. Solar PV panels will continue to produce power at 80-90% of rated output after 25 years, and battery storage will still have 80-90% capacity. I'm sure you can understand that as long as the system is storing and producing power at these levels, its value is not zero.
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