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Comment by throwanem | Hacker News Reader

My local power utility has ramped up its (thus far) voluntary load shedding campaign this year with rebates for usage reductions during high-demand periods (including today!), and is also pushing "smart" thermostats pretty hard, also in exchange for a minor rebate. They're "smart" in that they allow the utility to remotely shut down your AC for a 75% or 50% duty cycle, which you are not allowed to override.

Don't count on AC saving all that many lives as the decade wears on.

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50% duty cycle is more than enough to keep the temperature at a survivable level. If the utilities use the load shedding program to reduce AC usage to the point of killing people, the situation would already be so bad that the alternative load shedding approach of black outs would kill far more people.

It also helps to insulate the house and block the sunlight from the outside of the window. If you only use curtains, all the heat still get inside the house.

Norwegian company buildings are not allowed to install AC if you don’t have outside sunscreening. This is to save energy used by AC.

Rooftop solar (if you can) is the future. The cost will (must, really) come down, even if we need a "Solar Corps" (volunteers, Habitat for Humanity style) or similar to get generation on the roofs of the disadvantaged. AC load shedding will become untenable in the hottest of places, and the power grid will become taxed from demand faster than infrastructure upgrades can occur.

Tesla Solar Roof comes to mind.

https://www.tesla.com/solarroof

It’s unfortunately roughly double the cost of a regular roof (and 3x as much if your current roof is already due for replacement).

In Australia, the cost for rooftop solar is about $1/watt. In the US, we're still higher from soft costs such as permitting, utility review and approval, and similar, putting the cost closer to $2-$3/watt (pre 26% federal tax credit). The NREL recently released an app that automates the permitting process [1], but there are still places to squeeze the fat out to drive the cost down.

Tesla's solar tiles are interesting, but cost prohibitive for anyone but the wealthy.

[1] https://solarapp.nrel.gov/

(i facilitate, pm, and help with rooftop solar installs as time permits in the US)

Rooftop solar is tempting. I'm in the PNW so the economics don't work out favorably (even at $1.5/W installed, which is what I was recently quoted). But there are some non-economic advantages to having solar (as long as you have batteries) so it may still be worthwhile.

I’m in Portland, OR. I’m not sure what you mean by the economics not working out. We got a loan to pay for the solar panels. The loan payment each month is about $35 under our previous monthly electric bill. Any excess electricity our system generates is fed back into the system and we get a credit for it. So far (4 years) it has been enough that even in the cloudiest months we don’t pay anything to PGE above the base charge ($12) to be hooked into the system. Once the loan is paid off (in about 15 years), the panels are guaranteed to still be at 80% efficiency and our electric bill should be minuscule. Either way, the money we are paying is less than what we paid for our electric bill before panels.

The short answer is that I found that roof life expectancy was the real factor in determining whether the system was a good investment. The math is far more favorable if you install a 25 year roof at the same time you install the solar panels (and assuming that you needed to replace the roof anyway, or it was a new install on a freshly built house).

Roughly, the math for my situation worked out like this.

$20K out of pocket for a 13.5kW system, installed. This should, over a year's time, cover close to 100% of my average consumption.

Break-even time was something just over 11 years.

Existing roof is 10 years old. Reasonable life expectancy of the roof is 15 more years. Value of panels in 15 years is likely to be dwarfed by uninstall/reinstall costs when roof is replaced, so I call that EOL for the system.

The most optimistic scenario I can come up with, assuming PGE raises their rates 2.5% a year, is an ROI of 56K, which works out to about 10% annually. Not bad. But this only happens if nothing breaks, the roof really does last 15 years, the installed cost is only $1.5/W, and I invest $20K out of pocket (i.e. no loans).

So the way I see it, this is something to do for the non-economic benefits, e.g. installing battery so it will work when the grid is down.

There is quite a bit of room between what most people set their AC, what’s actually uncomfortable, and an even larger gap to what’s unhealthy. That delta is what allows load shedding in a heat wave. They don’t turn off the AC for days it simply goes on a longer cycle so the building might hit say 80f with low humidity.

In rich countries like the US throwing money at the problem works, but for the much of the world the extra infrastructure simply isn’t worth the extra comfort.

I'm in California where we have tons of solar generation. For much of the state, solar generation slopes off sharply starting at 4PM and it's still hot. That's when we tend to have the grid emergencies now. Houses with average insulation and pre-heated framing/attics can rise in temperature pretty quickly even if you've aggressively precooled the indoors.

Does your utility have a battery install incentive (Powerwall, LG Chem, etc) [1]? That’s typically what’s attempting to solve for the evening duck curve ramp in CA [2], enough storage to carry through from sunset to evening demand drop off.

[1] https://www.cpuc.ca.gov/industries-and-topics/electrical-ene...

[2] https://www.caiso.com/documents/flexibleresourceshelprenewab...

Yah, but it's not worth it even with incentive. It's cool for geek factor / having a major UPS and I may go for it for that reason.

I think batteries-- distributed or as part of utility-scale deployments-- can help a bit but are not economical enough to use to solve this problem.

It's going to take more of everything-- more solar overprovisioning, a lot more wind power, a fair bit of battery, more load shedding and demand pricing, more DC interconnect allowing power to be shipped large distances... and other stuff, like gas-to-power-to-gas and/or more nuclear baseload... to really let us move to an overwhelmingly renewable grid and have stable power.

The issue, IMO, is that there's many different timescales/types of shortfall (very cloudy couple weeks in winter with no wind vs. daily duck curve)... and then there's the 1 in 100 and 1 in 1000 events, too (heat wave in summer + overcast rolls in at 2:00PM trapping heat in all night with less insolation and little wind). Chemical storage can't blunt the longer timescale shortfalls much.

Nobody is going to throttle the ac to your million dollar home unless it’s Cali and even then probably not. Likely will only affect poor people.

I lost power for about 45min last year during one of the highest load days in California. No AC though so it didn't really do much except people went outside and talked about not having power.

East coast here, if you elect to participate in the program they can toggle your usage to 75% or 50% with advance notice.

Million-dollar home, that's cute. But that aside, by you I should what? Not give a rat's ass because it doesn't affect me?

If you have a west coast home it’s probably worth at least half a mil in any Major metro close to 1 for anything decent sized.

People who pay subsidized rates will be throttled but will still be colder than 10 years ago before ac was widely available, they will have to suffer at 80-85f while you crank it down to 68 and pay market rate for the privilege . That’s just how capitalism works and it’s not a bad thing

>they allow the utility to remotely shut down your AC for a 75% or 50% duty cycle, which you are not allowed to override.

Switches can be bypassed ;)

Makes me wonder how hard it would be to either just snip the control circuit from the utility provided thermostat to your AC unit and run your own in its place while retaining the discount, or setup an rPi or such as a MITM and intercept the control commands.

Alternatively: just don't overthink things and install a mini-split/window unit/small portable that doesn't get connected to the house thermostat in the first place.

These programs are optional. Google's Nest (among others) integrates with utility signaling to perform this shedding, and it's typically allowable for you to enable cooling and override the load shedding activated during peak demand (in the programs I'm familiar with).

I get that, I was just pondering the fraudulent possibilities of netting the discount while subverting any control the utility would take over your HVAC equipment.

You have to have a smart meter to qualify for the program, so it's not like they can't tell if you cheat from consumption data.

The smart thermostats BGE offers allow only two overrides per day, iirc 30 or 60 min each. Not sure on that part, but the specific period isn't so much at issue as that somebody else has the privilege of deciding when I am allowed not to swelter.

(I saw some mention of a "smart switch" also installed under this program, which I assume is there to prevent "overriding" the meter by just yanking it off the wall and shorting the contacts.)

> Not sure on that part, but the specific period isn't so much at issue as that somebody else has the privilege of deciding when I am allowed not to swelter.

You signed up for a discount for them to have permission to adjust your AC condensing demand run time when necessary, correct? I have never heard of a mandatory residential load shedding program in the US, but that doesn't mean they might be out there.

https://bgesavings.com/programs/ac/

> BGE‘s PeakRewards Air Conditioning program helps prevent the need for additional power plants, keep down the overall cost of electricity and ease the burden on Maryland’s electricity delivery system as the state’s population continues to grow. Plus, participants receive up to $100 in BGE bill credits each summer (June – September).

> The PeakRewards program is completely voluntary and is open to all BGE residential customers with central air conditioning or an electric heat pump in good working order, regardless of their choice of electricity supplier.

There's occasionally rolling blackouts. Those are mandatory load shedding.

> You signed up for a discount for them to have permission to adjust your AC condensing demand run time when necessary, correct?

No. You're right that the program is (currently) voluntary; I haven't volunteered, not least because I run the AC at 76°, I have and know how to use ceiling fans, and most months the bill barely breaks $150 if that - my house is 140 years old, and while that's not enough especially in Baltimore to say that its survival proves it is well designed, it is well designed.

This is targeted at two groups of people: fools who paid far too much for far too little and ended up house-poor in a place built last year that doesn't know how to stay cool, and folks for whom $100 a month makes a huge difference. One of those groups has my sympathy, especially because I expect they'll be first and hardest hit when these programs cease being voluntary because the state isn't investing enough in generation capacity and the city isn't investing enough in grid maintenance.

So you haven't even tried the program but you say it causes people to "swelter"? How do you know? And the rebate is "up to" $100, not $100.

If you're sweltering then maybe something is wrong with your setup. I've been on Rocky Mountain Power's version of this program for seven years and have only noticed that it's one or two degrees hotter than it should be maaaybe three times. In seven years.

Why don't you just unenroll from the program? I only get a $30 rebate per year. You make it sound like someone's holding a gun to your head and making you live in hell.

Just put a heated blanket on it if you need to override

If this became enough of a problem, it would be easy enough for them to start auditing your hourly power usage. I wouldn't be surprised if they were already doing so to see the impact of such programs, and also because bypassing a thermostat or installing a window AC unit is within the reach of most people.

sounds like it will incentivizes battery installation

Oh, it's trivial to take any thermostat off the wall and bridge the same contacts its relay would. That's not what concerns me, so much as that I think I see the thin end of a wedge.

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