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Comment by LUmBULtERA | Hacker News Reader

Given the dramatically lower costs of utility-scale solar vs. residential rooftop solar, is it not better at a society level for state policy to incentivize utility over residential solar? Utility-scale battery installations likewise should be much cheaper.

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This argument ignores the cost of transmission and distribution, which are higher costs than the generation itself.

And as electricity prices are driven down even further, T&D will come to dominate over energy generation costs.

Few models account for this, but Christopher Clack made one, and the lowest cost energy path was a small amount of investment in distribution now, paired with massive deployment of solar on homes and industrial/commercial.

This won't happen unless utilities are forced into it or their allowed profit model is changed to deliver ratepayers the lowest cost energy, however.

Unless every home is completely off the grid, you’re going to need to pay for most or the majority of that transmission and distribution anyway. Peak winter and summer I also would imagine many or most residential deployments aren’t going to cover their own need, unless they’re incredibly over built with massive batteries. In any case, I should check out your Christopher Clack reference.

The modeling is a few years old now, but here's a podcast episode diving into details:

https://xenetwork.org/ets/episodes/episode-146-why-local-sol...

(And of course, perhaps one modeler can get it wrong. But over here in California where the majority of our sky high electricity cost is from T&D, it definitet feels very true. And last national stats I saw had T&D as higher than generation costs)

As long as the houses are still connected to the grid you will indeed by paying for distribution costs. But I think that you should expect to see transmission savings since you'll have more of the demand met locally.

Why? If there's any possibility those homes will draw 100% of their power from the grid on any given day, then the cost of infrastructure will be pretty much the same since a grid failure is a disaster.

And there is a 100% chance they will, like my home is today, because 11kW of solar is making about 800W due to cloud cover which has persisted most days of summer.

You don't need as much grid capacity if houses have their own generation and storage.

The grid still needs to be built for the worst case - houses aren't going to have days of storage for a week of cold weather with dark clouds

Worst case is months. In the depths of winter you need energy captured from the sun during summer. That's a drastic rethinking of the scale of storage.

Absolutely. For the sake of the topic of discussion I was trying to think of Californian conditions but for places like Sweden you'll need completely different solutions (Sweden has been powered 100% on Hydro+Nuclear for decades now so that's one way)

My PG&E bill would make you think so.

But that is a PG&E problem (well problem for the consumer and great for their bottom line).

Generation is the majority of the cost across the US: https://www.eia.gov/energyexplained/electricity/prices-and-f...

Wouldn't that mean further subsidizing rich homeowners?

The people best positioned to take advantage of incentives own their own home and have the disposable cash to make the initial outlay for residential generation.

Yep, it definitely would. It doesn't mean we shouldn't still do it -- especially because richer folks tend to use more electricity and pollute more in general.

Residential solar may still make sense for new construction (maybe?) in the right areas. But there was a lot of scammy behavior around home solar installation at one point. Given that home solar does not effectively give you a backup generator for free (barring a lot of batteries and specific electrical hookups as I recall), it's not clear it's a big win in general. A lot of utility things aren't ideal at the individual house level if there's an option.

A lot of home solar installers now include grid tied batteries as part of a standard installation, which is what NEM 3 was intended to do (secondarily, after its primary goal of giving CA IOUs a massive free lunch).

Generally, yes, but a few items:

- Distribution systems today can only handle some percentage of EV penetration in a given area, not 100%. Charging an EV from the roof skips the grid entirely

- The bulk of the cost is labor and permitting, not the modules themselves. Given that, California requires solar on newly constructed homes

- California updated their net metering program so that ratepayers aren’t subsidizing rooftop solar anymore (in NEM 3.0, homeowners get paid wholesale rates)

"Charging an EV from the roof skips the grid entirely"

As long as you have enough sunshine hours in your region.

Southern Spain is fine year-round, but you won't get any meaningful output out of a solar panel in Finnish winter. The rest of Europe lies between those two extremes.

Northern winter will be made more challenging by addition of EVs to the grid, because a lot of electricity is being used for heating as well.

As far as rooftop solar, it makes a big difference if solar PV is built into the design process at the beginning, rather than tacked on as an afterthought. Similarly, a household battery might be as common in the future as a household hot water heater (with a similar footprint, size-wise).

There's also regional variability - cities absolutely require utility-scale solar, just as they require dedicated agricultural land to feed the population, because there's not enough surface area in a city. Rural/suburban areas on the other hand are ideal for integrated rooftop solar.

> Given the dramatically lower costs of utility-scale solar vs. residential rooftop solar

According to Wikipedia the LCOE on small roof top solar is about twice that of utility solar. [0] So yes, it's dramatically better. But typically the price difference between what the utility is paid and what the customer is charged is 3 times, so your average household is better off installing solar despite generating it at twice the cost of a utility.

The price difference isn't just transmission costs. It's also retail markup, regulatory charges and metering and billing.

[0] https://en.m.wikipedia.org/wiki/Cost_of_electricity_by_sourc... - there are a lot of tables in that page. Twice looks to be generous to the utilities.

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