Comment by derriz | Hacker News Reader

Comment by derriz | Hacker News Reader

I don't think the expectation that you can save money with rooftop solar will be economically sustainable in medium or long term. Energy (and nearly everything) produced at scale is simply cheaper whether thermal, solar PV, wind, etc.

Having rooftop solar should be viewed as analogous to having a home diesel generator (without being filthy for the environment). The goal isn't to save money by "doing it yourself at home" but there are other benefits like energy independence, redundancy, backup, etc.

The gridscale/utility market in PV is absolutely booming - "Solar and battery storage to make up 81% of new U.S. electric-generating capacity in 2024"[1] and is constrained by supply of batteries and PV panels. As someone deeply concerned about global warming, I'd rather any available PV panels be used in the most effective way to reduce CO2 emissions and that is in a grid-scale installation.

There might have been a case for direct and indirect incentives for homeowners to install PV 10 years ago to help boost overall demand for PV panels but there is no such need these days - the industry is booming and supply is a bigger issue than demand.

[1] https://www.eia.gov/todayinenergy/detail.php?id=61424

You save on transmission costs, so it’s not completely implausible that rooftop solar stays cheaper.

We save in stability: p.v. and co vary it's output far quicker than classic big power plant, this means that on grid we have more and more frequency stability issues. To compensate we need a smart grid witch is an IT nightmare and in any case it's not there.

At home, in self consumption, we are in a small smart-grid. So we can do our best to shift loads on p.v. using the grid let's say "for the base load", as a result individually we spend less and have (in case of batteries) backups, at grid scale peak demand is less intense and happen less.

That's the "issue" with p.v.: utilities do not want semi-autonomous homes, they do want to own, leaving others with nothing but subscriptions, paid services, this is incompatible with current state of tech while the current state of tech is perfectly compatible with small scale self-consumption.

Now try to imaging a hypothetical society where people living in reasonably sunny part of earth have p.v. and batteries. On scale it's probably not doable today, but we can definitively start. We still need a grid or some other backup, but we do not need an UPGRADED grid in capacity terms because most of the loads, the biggest one at least, happen locally. Surely without seasonal storage being autonomous it's a myth, but technically we can pass most day-to-day needs in largest slice of the Earth who happen to be the most inhabited as well. This means we can converge to electricity as main energy without consuming much more than today from the grid.

I think you are right, and what's happening with rooftop solar in urban environments like DC (as in OP) is a case in point. By and large, the rooftop solar here is directly integrated with the grid and net metered. It is not off grid whatsoever like a diesel generator would be. It's possible to install a backup battery and inverter, but if the power goes out, you don't get to use your solar directly.

Energy companies in DC, are incentivized by the govt to produce energy from renewable sources. They have to pay a penalty for SRECs they fail to produce, so they have good reason to convince consumers to put solar panels on their roofs and then buy SRECs from them at a rate lower than the value of the penalty.

Home PV + batteries could at least help tame the duck curve and at least moderate the cost of grid expansion which ultimately is a cost born disproportionately by low income homes which are already energy burdened. But yes I mostly agree with you in re: grid-scale PV (+ wind and storage) being much more significant.

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