Curious!

Even if they're at 50% capacity, they would still work, right? But if there are other considerations, especially safety ones, then that would definitely be a consideration. I'm not sure where to learn about this type of thing.

LiFePO4 generally degrades to 80% capacity after 10 years, that's it. Safety isn't an issue.

In the UK I would expect the roof to be tile, which lasts basically forever unless a storm hits hard enough.

I did have to have my panels taken down and refitted, at a cost of well over £1000, because I hadn't bird-proofed underneath them (wasn't suggested by original installer). So watch out for that one.

As long as the bond issuer remains solvent. How much do you trust bonds that yield 9% to retain their full value for 25 years?

"Another way to look at this is that the investment is returning ~9%/year."

EDIT: Two more things that will juice the return

1. Grid electricity prices will go up over those 25 years, at the very least tracking inflation.

2. Unlike bond coupon payments, the "return" from a solar installation isn't taxable. Because you're saving money, not getting paid.

You reminded me: David Roberts' often states that a hurdle for electrification and decarbonization projects is connecting them to "slow capital". Stuff like residential, community, solar, battery, heat pumps, appliances, ground source heat, yadda yadda.

I gather that there's plenty of "slow capital" perfectly happy with low risk long term modest returns. But these projects are too small to be worth the effort. Probably something about transaction costs.

My impression is there's an opportunity to bundle up these projects for the larger/largest investors. Biden's IRA created a "green bank" (RIP); maybe that was its intended function.

You're smart about money and finance, so you can probably explain what Roberts is talking about (to noobs like me).

https://volts.wtf

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 years have already done additional purchases. The payback time keeps getting pushed back to the point that when payback will happen your panel will be worthless in efficiency compared to new ones. At industrial / commercial scale it makes sense, but humans like to move houses, and do stuff in the houses and that messes with the payback plans at the individual level.

So either I was in the wrong countries or most people just gamble on the equipment lifetime, but for that I'd rather buy SPY calls, less drama.

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.

"An ATS (Automatic Transfer Switch) for solar is a crucial device that seamlessly switches your home's power between the utility grid, your solar panels/battery bank...

Making a system non-grid-tie is comparatively expensive, that's why grid tie is so common. People think you add solar + batteries and you're ready for doomsday - not quite.

Battery/solar doesn’t make sense in my opinion. Too many years to break even like this parent comment said and by the time you break even at 10 years, your system either is too inefficient or needs replacing. At least with the portable generator, you can move it with you to a new home and use it for other things like camping or RVing.

I installed 2800Wp solar for about €2800 ($3000, payback in: 4-5 years), and a 5kWh battery for €1200 ($1300) all in. The battery has an expected payback time of just over 5 years, and I have some backup power if I need it.

I’m pretty sure about the battery payback, because I have a few years of per second consumption data in clickhouse and (very conservatively) simulated the battery. A few years ago any business case on storage was completely impossible, and now suddenly we’re here.

I could totally see this happen for the US as prices improve further, even if it’s not feasible today.

In my country I've never had to deal with more than 15 minutes, twice in my life. In other countries its sometimes been a day but really I just go on with my life.

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

I personally like simplicity, I'd rather have money in an index fund and just pay a monthly bill over having a complicated solar+battery+car charger install at my house that I have to manage through various apps and dashboards.

If it is about impact on the world, invest in a clean energy index fund. Large solar farms and neighbourhood batteries operate at a much higher efficiency than domestic installations.

I get your point that in modern society, you can invest in an ETF in a few clicks, but in a way, owning your own infrastructure is simpler. Transform the sun into energy reserves with parts you can buy, understand, and install yourself from wholesalers.

A power company is opaque, carries overhead, and requires complexity to serve at an institutional level. ETFs have a similar complexity/abstraction to their customers.

> 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.

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

Not for everyone, but definitely for homeowners with suitable roofs and local utilities.

I'm happy to pay monthly to let my electrical provider handle all that, and I'll invest my money in something with a better return.