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This doesn't make sense - NYT article about a solar installation in the US

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james_s:

--- Quote from: Ed.Kloonk on October 30, 2021, 08:03:20 pm ---The question I have is how prepared was Texas in regards to being able to charge and run all those cars? The power supply seems to have coped. Unless it snows, of course.  :palm:

--- End quote ---


Disasters happen. We had a massive storm blow through here about 15 years ago that knocked down multiple large transmission lines and caused widespread power outages lasting well over a week. People couldn't get gas for their cars because the gas stations didn't have power to pump the fuel. It was not really any different vs people not having power to charge EVs. You can't plan everything around the sort of events that happen once in a century.

station240:
Good old Ohms law is responsible for most of the problems in this article.

You have two power sources:
1) Grid, 112V very low impedance.
2) Solar Inverter, 112V low impedance.
Note, this doesn't work as intended, as the grid has much lower impedance, also add in the losses into the transformer.
So the Solar inverters boost the voltage, say to 113V or even 115V, so current is drawn from the inverter instead.

However, there is a maximum voltage for the street grid, to avoid damage.
So at some point the solar inverters will shut down, and stop outputting power.
So the power companies have choices to make:
1) Limit how many kW of solar is on a particular street transformer. or;
2) Alter the tap on the transformer to output a lower voltage to start with (or just install new transformer anyway.
3) Install a transformer with auto tap changer.

Oh yeah, and likely some of these transformers needed replacing anyway, as too close to being overloaded or just old.
I suspect the US isn't doing themselves any favors by using 110V AC, as the extra losses in cables mean more transformers and less houses on each to even out the load.

As most of these problems exist in other parts of the world, there are solutions:
1) Demand management, digitally broadcast to homes when there is an over/under supply of power in their area. Whatever automatic system is in place can offer to increase/reduce by X kW, requires say fiber optic internet for low latency.
2) Neighborhood battery storage, install batteries to soak up excess power and sell it back at night. Only profitable if not charged utility fees, and the power company don't like that or others making money.
3) Install two separate inverters in houses, so solar/battery power still runs the house in cases of high grid voltage/blackouts. Some power companies don't like off-grid power solutions like this.

Personally I like the Neighborhood battery, it can work well, helps everyone not just those with their own solar/batteries.
Problem is it's not profitable if the power company want full line fees for sending power maybe 200 meters tops, as it's paid twice as in/out and isn't large scale.
Can also be setup as a way to "bank" power, generate excess during the day, get it back at night at the same price.
Could also be wired up to power the entire street to prevent blackouts, just switch the transformer out to prevent backfeed.

NiHaoMike:

--- Quote from: james_s on October 31, 2021, 01:47:49 am ---Probably a lot less difference than you might expect. Besides, even if everyone is in the office building they can't all just stop heating and cooling their houses. A large number of people have pets and they are generally comfortable under the same sort of conditions that humans are comfortable, you shouldn't let your house get scorching hot or freezing cold if your dog or cat is home.
--- End quote ---
You could only heat or cool the room they're in.

--- Quote ---Regarding storing air conditioning as ice, calculate how much ice you need to store say 6 hours of 36,000 BTU/hr, so over 200k BTUs of cooling for a modest house in a moderate climate.

--- End quote ---
It would be far more practical than using batteries to power air conditioners, it turns out that pound per pound, ice would store about the same as using batteries to operate air conditioners, but the ice is a few orders of magnitude cheaper, has no inherent limitation on lifetime, can be left at any "state of charge" for extended periods of time without degradation, and can be cycled indefinitely. The only real disadvantages are that it's only useful for HVAC (so not a complete replacement for batteries) and (for now) the lack of premade solutions that use it.

One ton of ice (about 1 "IBC tote" worth) would provide 288 kBTU of cooling, that's already more than your example.

Someone:

--- Quote from: station240 on October 31, 2021, 04:30:13 am ---As most of these problems exist in other parts of the world, there are solutions:
1) Demand management, digitally broadcast to homes when there is an over/under supply of power in their area. Whatever automatic system is in place can offer to increase/reduce by X kW, requires say fiber optic internet for low latency.
--- End quote ---
I believe that one came up on the forum before, but will repost the original here:
https://arstechnica.com/tech-policy/2021/06/texans-regret-opting-into-power-plan-that-remotely-raises-thermostat-temps/
Consumer received (likely upfront one-off) payment to participate in minor load shedding, then goes mental when thermostat is raised to 78° F (26° C) from 74° F (24° C).

You'd be amazed how demanding of absolute/selfish convenience the general public are. "why should I slightly modify my behaviour if its for the benefit of others" while completely ignoring the non-linear cost/inconvenience of complete failure/blackout.

Siwastaja:

--- Quote from: james_s on October 31, 2021, 01:57:18 am ---Disasters happen. We had a massive storm blow through here about 15 years ago that knocked down multiple large transmission lines and caused widespread power outages lasting well over a week. People couldn't get gas for their cars because the gas stations didn't have power to pump the fuel. It was not really any different vs people not having power to charge EVs. You can't plan everything around the sort of events that happen once in a century.

--- End quote ---

Yes, and often the best mitigation strategies are very simple and low-cost. For example, in Texas, owning some warm clothes just in case even though they consume 2 sq ft of valuable closet space.

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