upvote
Just ask California. They've basically conducted the experiment you asked for by adding substantial solar & battery. They haven't had a blackout since 2020 and are the most stable grid in the entire US.

https://cleantechnica.com/2026/05/30/california-lowest-whole...

reply
Your existing demand is not flat. Not flat over a single day, nor a single week nor a single year.

So you already have some spare capacity on the system.

If your demand peak was summer air con, then adding the solar makes the system more stable. This can be seen in a few grids that issue less grid warnings in summer now.

reply
In the Indian state of Bihar in the current summer season, the grid met the extra demand purely due to smart grid installed on rooftops. That state used to have shortage of electricity during peak summer until 2yrs ago

Not to mention solar contributed to more than 15 % of Indian summer demand which is crazily high due to 40+ degree temperature during the heat wave Solar that too decentralised is a massive boon

reply
You add 100x1day worth of battery capacity. Which is fairly economical even today (though not economical enough to actually shut down coal). Wouldn't work everywhere (winter in New England needs more than 1 day of backup) but works in some places.
reply
Trivially yes, for any locations with summer energy use peaks. The solar output will be the greatest when the demand for cooling is at its greatest.

Yes, for places with sizeable hydropower. You simply hold the water for longer.

Probably yes, for places where the need for redundancy is rare. Natural gas peaker plants are cheaper to build and simpler to operate with the tradeoff of being less efficient than combined cycle plants.

reply
Take a look at California. Their grid is routinely, daily, generating ~84% of its power from renewables [1] (with ~25GW of existing solar PV capacity, ~6GW of wind, and ~6GW of hydro). They are adding batteries rapidly [2] (with a goal of 52GW by 2045; they are 33% of the way there). They still have ~32GW of fossil gas generation capacity, but it is rarely used constantly at full capacity. They have plans for another ~21GW of solar PV on land that can no longer be farmed due to water shortages [3] [4] (enabling families to keep their land with long term lease payments).

Not everywhere is California, but solar and batteries are the cheapest form of generation in 90%+ of the world [5]. You simply keep building more solar collection, storage, transmission, etc. to orchestrate collecting this "fusion at a distance" and distributing it to loads. The sun rises every day, and will for our lifetimes. We continue to deploy batteries and solar at manufacturing capacity, while continuing to increase manufacturing capacity year over year. You fill any gaps with fossil generation until there are no longer any gaps to fill [6].

Tangentially, Australia is currently testing a battery with a 8 hour discharge capability [7] ("Long-Duration Energy Storage (LDES)"), as they are rapidly preparing for a network/team of battery storage facilities to assume grid health responsibility from their retiring thermal coal generators [8]. Certainly there is much work ahead in understanding and developing longer duration energy storage systems.

[1] https://app.electricitymaps.com/map/zone/US-CAL-CISO/live/fi...

[2] https://www.energy.ca.gov/data-reports/energy-almanac/califo...

[3] 21GW of Solar for California Land That Can No Longer Be Used for Agriculture - https://news.ycombinator.com/item?id=46488648 - January 2026

[4] https://valleycleaninfrastructureplan.com/

[5] Solar electricity every hour of every day is here and it changes everything - https://ember-energy.org/latest-insights/solar-electricity-e... - June 21st, 2025

[6] Renewables reached nearly 50% of global electricity capacity last year - https://news.ycombinator.com/item?id=47615756 - April 2026 (149 comments)

[7] https://www.yahoo.com/news/science/articles/australias-first...

[8] https://www.aemo.com.au/-/media/files/initiatives/engineerin...

(think in systems)

reply
> Take a look at California. Their grid is routinely, daily, generating ~84% of its power from renewables [1] (with ~25GW of existing solar PV capacity, ~6GW of wind, and ~6GW of hydro).

> ... Not everywhere is California, but solar and batteries are the cheapest form of generation in 90%+ of the world [5].

... Then why is electricity so expensive there compared to the US average?

reply
It's not. California has the cheapest wholesale electricity prices in the country. It's the only place in the country with a wholesale rate below $100 / MWh, and California is way below $100.

https://cleantechnica.com/2026/05/30/california-lowest-whole...

Retail prices are of course super high in California, but that has nothing to do with generation.

reply
Why is there such a disconnect?
reply
Transmission and distribution costs: i.e. the grid.

California is a massive state, has very rugged terrain, and there's a ton of deferred maintenance on transmission lines that are more than 50 years old, that are at huge risk of causing massive wildfires that destroy entire towns.

This has been terribly mismanaged, because like most places with regulated monopoly utilities, the regulatory body is opaque and not very responsive to the needs of the public.

The utility doesn't make money on electricity generation costs, but it does get to take a fixed rate of profit from grid infrastructure costs. So the obvious game for a for-profit regulated monopoly utility is to jack up the grid costs as high as possible, try to snow the regulators to possible cheaper alternatives, and rake in more money.

I remember one case where PG&E got approval to charge for grid maintenance, spent hundreds of millions, had ~$100M leftover, then declared "oh we did it cheaper than we expected, executive bonuses all around the C-suite with the extra!" And then we had multi-billion dollar wildfires the following year.

Utilities are not normal businesses, they make more money by increasing their input costs. (See also the US healthcare system where incentives are similarly perverse... Insurance company profits are capped at a fixe percentage of health care expenditures, so the route to more profit is to increase health care expenditures.)

Of my decades in California, there's been a single gubernatorial candidate with deep knowledge of the grid and how to fix the regulatory structure, and it's the governor who actually appoints people to the regulatory board of the utilities, so the governor and their appointees have the power to fix this. That gubernatorial candidate was Tom Steyer, and he had/has fantastic plans, but I fear he just lost the primary:

https://www.volts.wtf/p/tom-steyer-wants-to-be-californias

reply
politics. Supply is cheap, but California has a corrupt relationship with the monopoly provider, and lets them get away with bundling all kinds of costs into the distribution charge. fire rebuilding, social projects, decades of infrastructure neglect from previous corruption.

Go and compare the rates from a non-pg&e distributor (eg SMUD in sac) and you'll see, supply is cheap enough and it doesnt have to be this way.

reply
A distribution grid for 40 million people in a high fire risk geography [1]. Renewables drive down supply costs, but not distribution costs (unless you can go off grid, etc). They could also improve costs by nationalizing PG&E (I argue, cutting out shareholder returns and excessive management comp), but that is an argument for another thread [2].

[1] https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...

[2] "Where’s all the f&$#ing money going?" The Waste and Costs of American Utilities - https://www.thebignewsletter.com/p/wheres-all-the-f-and-ing-... - May 22nd, 2026

reply