[XorNot]

If batteries were literally free today, they still wouldn't be good enough due to the cost in support electronics required to put them on the grid (which is currently about price parity with batteries per watt).

EDIT: and those electronics also degrade - a lifespan of 20 years would be reasonable at scale.

[svnt]

So you’re charging twice for the grid tie? Because the reason for installing batteries would be 1) to not grid-tie, or 2) to grid-tie along with a renewable energy source, which if it is a commercial site, is already grid-tied.

[XorNot]

It's the same thing: the inverters and support electronics needed for batteries currently cost, per watt, about the same as LiFePO4.

You can't run "bare" LiFePO4: you're either forming a grid, or you're connecting to one. Both involve BMSes and inverters.

[jaggederest]

But that's already cheaper than building new coal or natural gas plants. The cost per watt of solar plus battery, right now, is the cheapest available form of power. I don't understand why you don't think that it's going to replace a majority of primary and secondary energy usage on the planet relatively quickly.

I'd bet a dollar that, in 50 years time, nearly all energy usage is going to be primitive biofuels or solar-PV-origin.

[XorNot]

The sticker price of any given power source is irrelevant: the question is how much does it return on the investment.

If building a solar installation is cheaper per kW then building a gas generator, that literally doesn't matter if the only times the solar installation generates power is when power prices are negative.

[jaggederest]

Including batteries. It's a peaking plant in a can. As far as I can tell the all-in non-land costs are cheaper, full stop.

I also did the analysis for new nuclear under a relaxed regulatory regime (i.e. substantially cheaper and faster than now) and there's no way it wins. For the price of a gigawatt of nuclear, you can get 5 gigawatts of solar that's online next year, plus half a gigawatt of battery.

I could be wrong, I'm just an armchair economist on this stuff, but I just don't see how it makes any economic sense to build anything but solar unless you're located somewhere remote and arctic (i.e. Åland or something)

[XorNot]

But it's the half gigawatt of battery which is the problem - it's nowhere near enough. Roughly batteries scale 1:4 power-to-energy. So 0.5 GW is only about 2 GWh of actual storage. But you need that for almost 18 hours a day since solar tends to have about 6 productive hours a day. So your batteries are covering you for maybe 0.1 GW of constant draw - presuming nothing goes wrong (i.e. a week of regional cloud cover).

On top of that the solar plant capacity factor is somewhere between 10% - 30% in most locales, so the sticker plate capacity of 5 GW is going to be under 2.5 GW at best (and that would be a 50% capacity factor).

I've never been able to find a way to square an actual "no fossil fuels grid" with the supposed cheapness of solar or wind - it always feels like people are quoting selectively useful $/GW values and then not giving a full accounting of the assumptions behind them - i.e. GW type quotes originate with thermal powerplants which have capacity factors which are essentially "whatever you want if you pay us".

[svnt]

That’s a cost on a renewables installation though, it doesn’t need to be loaded on the batteries. You aren’t installing bare solar panels either.

[XorNot]

The hardware to manage batteries and the hardware to manage solar panels is different (but sometimes can be packaged into the same box, or with one-off benefits like hybrid inverters), with batteries being considerably more complicated. You would struggle to ruin a solar panel with a bad inverter. You can completely destroy a battery by over-discharging it once.

A solar panel produces energy. A battery only stores it (and loses, round trip about 8% in the process) - which is to say, batteries are solely arbitrage instruments.

[svnt]

You started out loading the whole cost for a grid tie. Now you are talking about a BMS. A BMS is typically included in the cost of batteries.

Batteries are extremely functional in many installations, and even if you’re not using, only selling, arbitrage can work well. This is especially true if you get paid to accept the commodity in one time window and can get others to pay you to take it later.