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> If a house on average generates as much as it uses, the electric bill will be zero. (In practice there’s a minimum monthly fee, but it’s pretty low.)

This was the case in the last house I lived in. The solar panels generated enough power that there was never an electric bill other than the $12 fee to be hooked into the grid. And this was in cloudy, rainy Oregon.

I did think about this scenario. If everyone had panels like that house, how could PGE make any money?

Note: we lived in that house for about 10 years before installing panels, so we knew the average monthly electric bill. We paid for the panels with a loan and the monthly loan payment was lower than any of our monthly payments during the previous 10 years. It was cheaper to get panels and pay the loan than to pay the monthly electric bill without panels.

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If everyone had panels, the kWh price for daytime usage would be $0 or close to zero. Everybody would still pay almost fully for nighttime usage, while daytime usage and production would not have any impact on the bill. Either the fixed part of the bill or the nighttime price would grow as needed to cover the actual cost of the grid and the cost of energy on cloudy days.

Either way, the new pricing would stimulate the installation of solar-powered batteries, to arbitrage between expensive nighttime consumption and cheap selling of surplus production in the morning.

On cloudy days the grid would have to supply almost-free energy at noon, but then would also make more money at night because households batteries wouldn't have enough charge. I'm not sure if this is true in the summer, when even on a cloudy day there might be enough sunlight to charge the battery, but the actual balance would guide the utility company on how much to increase the fixed part of the bill vs the nighttime price.

I am not usually a fan of the efficient market hypothesis, but here it seems to work albeit with some serious simplifications.

> If everyone had panels, the kWh price for daytime usage would be $0 or close to zero. Everybody would still pay almost fully for nighttime usage, while daytime usage and production would not have any impact on the bill.

Right - but this is different that everyone expects it to work. People expect to sell power to the grid when the sun shines, then get the same power from the grid at night and offset them to be net zero cost. It is not sustainable pricing.

Sure, but nobody promised kWh offsetting would remain in place forever. $ offsetting can still save you money.

Also, because you entered the solar market first, you might have easier access to credit to upgrade it with batteries. So you'll benefit from price arbitrage more than the late-comers who have just taken a loan to install a solar roof and can't afford the batteries right now. Or you might buy a plugin car, charge it cheaply when the sun is high, and save on gas expenses (that's what I do since I work from home, :) and it's possible to both top up the car and charge the 4 kWh solar batteries in most sunny days with a very small 3 kW installation).

Which brings up another problem especially in Europe: taxes on gas are financing roads and the like in ways that sooner or later will have to be covered by increasing electricity prices. Right now, early buyers of electric cars are having their purchase subsidized because effectively they pay fewer[1] per-km taxes than owners of ICE cars.

[1] not just less taxes, also literally fewer

Taxes on gas in Europe pay more than just the roads, they're regularly used for general govt expenses. You're right eventually the tax has to go somewhere else.

> The solar panels generated enough power that there was never an electric bill other than the $12 fee to be hooked into the grid. And this was in cloudy, rainy Oregon.

Yeah, this is it in a nutshell. You were only being charged $12/month for a grid connection, when a grid connection was clearly worth much much more than that. The usual cost of a full off-grid system can clear $100k if it's sized to cover HVAC.

> The usual cost of a full off-grid system can clear $100k if it's sized to cover HVAC.

Or is essentially absurd... my 6.6kW system generates about 3x more than we need for 8 months of the year, but about 1/3 of what we need for 4 months of the year (the period when our air-source heat pumps, aka minisplits, are in use).

To be able to go off-grid would require either:

    - a systems 3x bigger than we have, generating 9x more power than we need for 8 months of the year

    - a gigantic (10MW?) battery system to store the excess power from the summer

Neither of these make any sense to me, and seem like well-intentioned but fundamentally ill-conceived designs.

This is a fair observation. Interestingly, what you describe (a system 3x larger than your average load) is essentially what the grid has to have. Looking at the California data, here in Winter, today's peak usage is about 28 Megawatts and the overnight low is about 20MW. However, the peak all time usage for California is over 50MW. Our entire electric grid has to handle that 100% delta in usage; it's not surprising that a personal grid would have to handle at least that much delta. That's just what is required to have 24x7x365 electricity; you can't hide from that reality.

But doesn’t California have rolling blackouts? That makes it seem like the grid needs to be larger than 3x.

Not usually. There are grid shutdowns in wildfire risk areas during high wind events, and there was a brief rolling blackout last year over two nights in a small area, but it's been almost 20 years since the broader blackouts that made national news:

https://www.marketplace.org/2021/07/22/a-california-fix-for-...

It's not about hiding from the reality. It's about how energy storage (and generation) systems scale and can be activated/deactivated.

On the generation side: If I had put in a 21kW system to cover our winter needs, the extra power it generates during the summer would have been unconditionally generated. Do this broadly across the population and the power grid has a substantial management problem. Conversely, utility-run systems are likely to be built so as to be much more modulatable, to match demand.

On the storage side: yes, obviously the total storage required is the same, but for more or less all the technologies I'm aware of today, this would be much more efficiently done with large storage systems than per-household distributed ones.

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