This doesn't make sense - NYT article about a solar installation in the US - Page 1
Forum section: electronics / general

author: ckambiselis
author_rank: Regular Contributor
timestamp: October 29, 2021, 04:20:25 am
content: Here's an article from the NYT that makes me wonder if the correct writer was chosen to write it. (The link is a bit long because I used the button that gives you access to the full story with having to pay)Old Power Gear Is Slowing Use of Clean Energy and Electric Carshttps://www.nytimes.com/2021/10/28/business/energy-environment/electric-grid-overload-solar-ev.html?unlocked_article_code=AAAAAAAAAAAAAAAACEIPuonUktbfqohlSFUZCybfQMMmqBCdnr_CxrEmiW67IS6LSCxFyeEYBZTH9kPAbrZ5ZtB20C6aSJpGLrI1QPt7wqpEOEhkUUylvN2EhJEBaW0TmL6EY1kXjdjLTKxqtnjjdHW4I-Nyg-fh5RzZa2DhRKXZ2XM-IF1goo82dQqoxXJekquWQOR339J1j-wzRcwvHUd2byGItvTjDh9-PczXLU2Pr1lrBJwKHG3bjtWe6LofcAxNClKgTX534Ww06t00K8pAde-kbEZmIJyi9O1XXm94L46pB4kyR5zXlNhotL3Oqx-Nwamm1gOP1yYDNTuTwh7SXho8g_I

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: October 29, 2021, 08:52:50 am
content: Whilst I heard about this story elsewhere, the article don't tell us more than what we already know. I'm wondering if it was simply a non-story and the paper has sexed it up with keywords to attract google juice and eyeballs.

author: richard.cs
author_rank: Super Contributor
timestamp: October 29, 2021, 04:32:21 pm
content: This is a well understood problem isn't it? The electricity network impedance is on the high side, and the transformers are set near the max voltage so that the minimum voltage can be maintained at the end of the line without generation. Then when you have generation and the voltage slopes the other way the inverters trip on overvoltage. Sometimes you can put the transformers on a lower tap, sometimes you have to add more copper to get the impedance down.How much it costs to fix depends exactly which part of the network needs adjusting. It's probably worse in the US style system of many small transformers. Do those even have selectable taps or does it have to be fixed at MV?

author: bdunham7
author_rank: Super Contributor
timestamp: October 29, 2021, 04:44:06 pm
content: Quote from: richard.cs on October 29, 2021, 04:32:21 pmNo, they typically don't have and don't need taps. Actually the small local transformers work very well where they are used, which is in the vast majority of rural and suburban areas in the US. Problems such as are reported here are the result of very advanced decrepitude in the main distribution system, along with poor understanding and planning when installing the systems that they are talking about. The people with the solar system that they can't hook up should have thought about batteries and the guy whose Tesla melted his panel (or whatever) should sue his electrician.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 29, 2021, 04:57:23 pm
content: There are two solutions;Fix the grid,Or accept broken grid and add local energy storage, creating your own island of better "grid". The original grid then becomes just one unreliable source of energy that can be consumed when it's available and needed. Also push back some charge into that grid when that is possible, at power level which works.Living with crappy infrastructure sucks but really, what can you do. Complain to politicians; or build a proper system for you; possibly shared with neighbors if they are sensible people.I'm lucky to have decent grid available but if it wasn't so, I would see no other option than to build by own island consisting of solar, possibly wind, battery storage, thermal storage and diesel generator (with waste heat recovery). Then if there was some joke of a grid, I could consider adding it to my mix, depending on the monthly/yearly fee.

author: richard.cs
author_rank: Super Contributor
timestamp: October 29, 2021, 05:35:24 pm
content: Quote from: bdunham7 on October 29, 2021, 04:44:06 pmOut of interest, do you have any idea what the typical source impedance measured at their LV terminals is? The large transformers in European-style distribution are about 10 mOhm so impedance seen by the consumer is utterly dominated by the cabling and usually 100-300 mOhm

author: bdunham7
author_rank: Super Contributor
timestamp: October 29, 2021, 06:03:58 pm
content: Quote from: richard.cs on October 29, 2021, 05:35:24 pmThey typically rate them with a 'Z factor', which is the percentage of the OC voltage required to circulate full rated current into a short circuit. So if you had a very typical 50kVA transformer at 250V and a Z of 2% (which I think is actually stated as 0.98 for some reason) then that implies that it takes 5V to circulate 200A, so that equates to 25mR. It also results in a maximum fault current of 10kA, which is the maximum for typical residential panels and breakers. In my case, the relatively short (30 ft) of wire between that and my panel is probably about the same 20 to 30mR.This type of transformer is what you would find in my neighborhood feeding 4 houses, each with a 200A service panel. They are very conservatively rated, something like 175% continuous and 400% for one hour at 23C.

author: rstofer
author_rank: Super Contributor
timestamp: October 29, 2021, 06:21:12 pm
content: Transformer impedance is measured, not in Ohms, but in percent. The percent impedance is the percent of primary voltage required to create full load output current into a short circuit. A standard oil filled transformer might have 6% impedance.In the end, this means that 6% impedance can deliver (1/.06) or 16 times nominal full load current into a short circuit.Take a 240V 75 kVA single phase transformer which should have a nominal secondary current of (75000/240) or 312.5 Amps. Now multiply this by the 16 value and get a maximum fault current of 5000 Amps. This i a convenient result because most residential circuit breakers have a 5,000 AIC (Amp Interrupting Capacity).This 'back of envelope' calculation assumes an infinite fault capability on the primary which is not true but it's good enough for the AIC calculation.That's why several houses will often share a single 75 kVA transformer in a neighborhood.I didn't read the article but I used to have a 8 kW solar array and never had a problem. My net utility bill, settled up once per year, was just the meter charge of $5/month. I still used utility power at night but I sold back a lot of power during the day. In my area, it doesn't pay to over-generate because the customer is precluded from becoming a net generator.The charger for my Chevy Bolt takes about the same amount of power as my microwave. Think about Thanksgiving and all the concurrent ovens, stoves and microwaves. I don't think EVs are going to be a problem. The fast chargers may be an issue, I don't have one,

author: thm_w
author_rank: Super Contributor
timestamp: October 29, 2021, 09:12:54 pm
content: Quote from: rstofer on October 29, 2021, 06:21:12 pmIf you use a 110V charger sure, which is adequate for majority of people.But in home level 2 "fast charger" will go up to 11kW:https://insideevs.com/news/488289/chevrolet-pays-installation-cost-home-charger-bolt/and its not that expensive to install.So maybe they should consider discouraging installing these instead of subsidizing them? Or at least build in some grid detection, etc. to charge at optimal times, or throttle charging.

author: james_s
author_rank: Super Contributor
timestamp: October 29, 2021, 10:21:56 pm
content: Quote from: thm_w on October 29, 2021, 09:12:54 pmI don't think it will be a problem. I have a hot tub that draws 11kW if both pumps and the heat are on full power. My clothes dryer is 5.5kW, I used to have an electric stove in the kitchen that I think was around 10kW fully utilized but that's gas now. The only EV I have direct experience living with for a while was a Tesla and in that you could set the charge current to anything you want up to the max, so if it's on a shared circuit or grid capacity is limited you can back it off. It's only a matter of software to make it coordinate with grid capacity, which it could even guess indirectly by monitoring the incoming voltage.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: October 29, 2021, 10:36:41 pm
content: Quote from: james_s on October 29, 2021, 10:21:56 pmYeah. I think it's a bit of bullshit that the grid can't take it. We just need to figure who it is and why. My understanding about load capacities on the grid has more to do with anticipation rather than actual heavy load. It costs money and effort to fire up an additional power source. I think that's the problem. Follow the money.

author: Someone
author_rank: Super Contributor
timestamp: October 30, 2021, 01:06:19 am
content: Quote from: Ed.Kloonk on October 29, 2021, 10:36:41 pmIts a well known problem, sure you as an individual would probably get away with moving more of your energy use to electricity and the grid would cope. Just like you don't feel like you're causing the traffic when you individually choose to drive. However, if all/most or even half of transport is suddenly moved from fossil fuels to electricity (as countries are planning to do in the next 20 years) its a very big problem:http://www.withouthotair.com/c18/page_103.shtmlhttps://www.iea.org/sankey/#?c=United%20States&s=Final%20consumptionor Australia if you prefer:https://www.iea.org/sankey/#?c=Australia&s=Final%20consumptionRoad transport uses more energy (annually) than the current electrical supply. So where is the plan to more the double the electrical generation? Will people play nice with their vehicle charging and only do it during off peak when there is sufficient grid/network capacity? (no, they won't, just like most people drive in peak hour and create the traffic jams).Its going to need some new market mechanisms to price the cost of delivering that energy more fairly (supply charges based on network connection size would be one place to start, as France etc already do). Market pricing of consumption would contribute, but that remains poorly connected between wholesale and retail.

author: Marco
author_rank: Super Contributor
timestamp: October 30, 2021, 01:16:31 am
content: It's only in the last two decades that electricity use has been somewhat stable. Before that it doubled every two decades since the 60s and even faster after WW2.Of course we were a little more progress oriented in those days. Endless lawsuits against eminent domain, endless lawsuits about permitting, species of endangered whatevers or archaeological finds in every plot of land stopping work, lack of cheap labour which doesn't care working far from home ... it's kinda hard to work at the pace the west sustained in the past.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: October 30, 2021, 01:37:26 am
content: Quote from: Someone on October 30, 2021, 01:06:19 amI know what you're saying. But supply of power is based on economics. The grid will cope just as soon as they figure out how to charge for it. Too many ppl factor the new EV car at current supply prices.

author: Someone
author_rank: Super Contributor
timestamp: October 30, 2021, 02:48:38 am
content: Quote from: Ed.Kloonk on October 30, 2021, 01:37:26 amThe grid (Australia and US) doesn't cope with existing peak demands, the current model already fails on that point. For all the talk of moving to electric transport there hasn't been any planning on how the grid will support that and where the generation will come from. Technically possible, yes, but the free market won't deliver it as the current market they play in is largely for show/theatrical (monopoly distributors, cartel generators).You put it pretty simply:Quote from: Ed.Kloonk on October 29, 2021, 10:36:41 pmThe grids don't have spare generation capacity, or spare carrying capacity right now (recent outages/curtailments and inability to carry more distributed solar). Neither do the grids have trajectories or plans in place to grow at the rate required by electrification of transport by 2040/2050/etc.

author: bdunham7
author_rank: Super Contributor
timestamp: October 30, 2021, 02:54:05 am
content: Quote from: Ed.Kloonk on October 30, 2021, 01:37:26 amUnfortunately not.But supply of power is based oneconomicspolitics.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: October 30, 2021, 04:18:39 am
content: Quote from: Someone on October 30, 2021, 02:48:38 amThe time from now until 2040/2050 is a long time to provide what ever cabling is needed to be just enough for normal supply. Nobody is going to do it on the off chance electric cars become a big hit.Temporary, localized drop outs are the future because the ramp-up of loads have become orders of magnitude bigger than what we have gotten used to. I'm not disagreeing with you. But infrastructure occurs after development. Always will.

author: tszaboo
author_rank: Super Contributor
timestamp: October 30, 2021, 05:40:58 pm
content: So if I know anything from the USA, there are three pretty basic solutions to any problem.1.) Shoot it with a gun. Transformer blows up, they install a new one. Or:2.) Sue them for millions of dollars. Or:3.) Wave a flag, and claim you're the land of the free and chant whichever part of the constitution.I think 1 and 2 would actually work.

author: james_s
author_rank: Super Contributor
timestamp: October 30, 2021, 06:18:08 pm
content: Quote from: Ed.Kloonk on October 30, 2021, 04:18:39 amOff chance? It has already happened, electric cars already are a huge hit. The area where I live is absolutely crawling with Teslas, the model 3 is one of the top selling cars in the world.

author: PaulAm
author_rank: Frequent Contributor
timestamp: October 30, 2021, 06:50:42 pm
content: There''s this odd belief in the US that electric utilities exist to generate and distribute electricity. That may have been true at one point, but today their sole purpose is to generate money.My electric bill is split between distribution and generation charges. The distribution charges are always greater than the actual cost of electricity. Despite having the highest (or maybe second highest) electricity rates in the country, we got nailed by a 5 day outage earlier this year from Summer storms. "We'll do better" they say, just let us raises our rates some more!I get oodles of ads about "green investment" and "green power" by the utility. It's fine when they put up the farms and charge you a premium. For local solar arrays, they are phasing out net metering and will eventually be charging for every watt that goes across their meter. When I put up my array, I could only put up about half of my yearly demand, and I had to fight for that.I picked up another 25KW of panels earlier this year and will eventually be moving to off-grid. Reasonable storage is the biggest obstacle at this point, but a couple technologies look promising and there might be something available when I get there.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: October 30, 2021, 08:03:20 pm
content: Quote from: james_s on October 30, 2021, 06:18:08 pmThe 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.

author: Bassman59
author_rank: Super Contributor
timestamp: October 30, 2021, 08:57:37 pm
content: Quote from: PaulAm on October 30, 2021, 06:50:42 pmIndeed. And they're regulated so they try to buy their way onto each state's regulatory agencies.QuoteThe original reason for the separate generation and distribution charges was that somehow, magically, there would be "competition" in the generation market, and customers could choose who generated their power. Since there is only one set of cables that come to your house, the local provider was responsible for maintaining them.I know there were attempts to form co-operatives for generation, but I honestly don't know where or if anyone has a choice for their power generation.QuoteThe utilities are generally against customer-rooftop solar power. They certainly don't want anyone over-generating and they don't want to pay retail rates from the customers with solar who are tied into their grid. Also the utilities are our "battery" so they need the ability to spin up and spin down generators "quickly" as solar production drops and rises.But basically they are just annoyed that they don't get the guaranteed profits that come with being a monopoly.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 30, 2021, 09:14:02 pm
content: Quote from: Someone on October 30, 2021, 01:06:19 amProvide incentives to move demand off peak and it will happen to some degree. One example is Ohmconnect.Quote from: Ed.Kloonk on October 30, 2021, 08:03:20 pmIncentives to try to match demand to supply would also help a lot with that. Going further, they should also have programs that give customers the option to be first in line to be disconnected and run on generators or other backup supplies, getting paid to do so.

author: rstofer
author_rank: Super Contributor
timestamp: October 30, 2021, 09:48:03 pm
content: Quote from: Someone on October 30, 2021, 02:48:38 amNone of the electric public utility systems in the US are 'free market'. They are all controlled by Public Utility Commissions. The PUCs tell the utility what to do, when to do it and how much extra they can charge for the results.Most people work during on-peak hours, that's why the demand is called 'on-peak'; buildings are up and running. Charging at home, after work, will be during a period of reduced demand. But, not to worry, if things get out of hand, the utilities will move to Time Of Day billing. They already have tariffs (regulations) in place and the rates are available as an option (at least here in Northern California with PG&E). They will just convert everybody. For the most part, the revenue meters have already been converted to Smart Meters which are read over the power line so getting instantaneous or interval demand is trivial. You may note that there hasn't been a meter reader (person) in the neighborhood for a decade or more.I'm not the least bit concerned about grid capacity to charge EVs and you have never seen a utility representative worried about it either. All you see is EV naysayers stating their opinion about the inadequacies. EVs already have a programmable start time (or end time) as part of the firmware. That's cool! Tell the car you want it fully charged by the time you finish your cup of coffee in the morning (end time) and it will start the charging as required. It remains for the car owner to have a large enough charger to get it done.At a very high level, there must be a plan to make it work because the auto manufacturers are investing billions of dollars in new plants to build EVs. Internal combustion vehicles simply won't be available in the near future. Like them or not, you will eventually be driving an EV.Gasoline here is $5/gallon and if a car gets 20 MPG, that's about $0.25/mile. If we take 3.7 miles per kWh and $0.25/kWh this works out to $0.07/mile. And no semiannual smog check! And we can drive in the HOV lanes without a passenger required!What's really cool is when you have a solar array under a power purchase agreement at, say, $0.15/kWh. That brings the cost of driving a Bolt down to about $0.04/mile. Try that with a gas driven SUV. And the EV will accelerate faster from a stop light - something I do from time to time.

author: rstofer
author_rank: Super Contributor
timestamp: October 30, 2021, 09:55:37 pm
content: Quote from: NiHaoMike on October 30, 2021, 09:14:02 pmRunning on generators is contradictory to the goal of reduced emissions. That would be the absolute worst way to provide power.Work from home is pretty popular and I'll bet houses are more efficient than office buildings because the workers pay their own utility bills. A laptop doesn't require all the features of the modern office building. I think I would work from the patio for about half the year. Poke at a spreadsheet while watching the dogs run and play. Pretty easy life!

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 30, 2021, 10:54:01 pm
content: Quote from: rstofer on October 30, 2021, 09:55:37 pmIt would happen rarely so not much in the grand scheme. Also, it means that the first ones to get dropped for demand reduction should the grid get crippled would be the ones prepared to deal with it. Additionally, there could be different amounts of reward given and/or different priorities depending on the kind of generator, more for generators that run from renewables such as biodiesel or wind/solar. There could also be a separate incentive program for CHP generators in cold areas, to export to the grid when demand is high and get paid for that, with the excess heat stored as hot water for later use.QuoteLikely to be true in areas where HVAC is rarely used, otherwise it would use far less energy to heat/cool an office building instead of many houses, even under the assumption that not all houses would be unoccupied during the day. Where there would be a huge energy savings would be the reduction in driving.

author: Someone
author_rank: Super Contributor
timestamp: October 30, 2021, 11:08:56 pm
content: Quote from: rstofer on October 30, 2021, 09:48:03 pmWhich is what I said, they arent actually market driven.Quote from: rstofer on October 30, 2021, 09:48:03 pmCurrent time of use tariffs are barely connected to the live cost of energy, at most I've seen a 2 season split. So the tariffs are a heavily averaged guess of the average cost, still noting to incentivise people to use less power when supply (or delivery) is constrained. Only moving people to the average time of day when its typically less constrained.The peak demands (as cause outages/curtailments) are currently derived from mass use of electric HVAC, a big part of average energy use:http://www.withouthotair.com/c18/page_103.shtmlTime of use is not solving that and won't squeeze the future EV demand into the excess generation available.Quote from: rstofer on October 30, 2021, 09:48:03 pmThat may help with the delivery (network) constraints, but doesn't explain where the new generation capacity will magically come from. Cars are quicker to build and deploy than power plants, plans/policy is in place to require electric transport, but there is no matching policy or plan to increase generation.Quote from: rstofer on October 30, 2021, 09:48:03 pmUS is on the low end of electricity pricing relative to petrol when compared worldwide:https://www.eevblog.com/forum/chat/problems-if-we-all-had-tesla-cars/msg705793/#msg705793And you take the classic EV-nut approach of your choice car designed for energy efficiency shall be compared to gas guzzling bricks, instead of other vehicles designed for energy efficiency (50-60MPG). So keep convincing yourself, but its just the same old reality distortion.You're in a pricing structure (low road tax, flat(tened) electricity) that encourages you to use those supplies (roads and electricity) for your advantage and pushing the costs equally onto everyone else (in the state/country). Its the opposite of a market, and with insufficient personal disincentives the system lacks negative feedback and is almost certain to fail (traffic jams, blackouts).

author: Someone
author_rank: Super Contributor
timestamp: October 30, 2021, 11:14:42 pm
content: Quote from: NiHaoMike on October 30, 2021, 10:54:01 pmThis is one possibility that could make a big dent in generation and network inadequacies as (above) the worst peak demands on the electricity grid are almost entirely from space heating/cooling. There are groups looking at larger commercial and community/district sized CHP/trigeneration too.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 30, 2021, 11:58:10 pm
content: Quote from: Someone on October 30, 2021, 11:08:56 pmThat can be economically solved by adding thermal storage (particularly for air conditioning which can be stored as ice), but there needs to be incentives to build it.

author: james_s
author_rank: Super Contributor
timestamp: October 31, 2021, 01:47:49 am
content: Quote from: NiHaoMike on October 30, 2021, 10:54:01 pmProbably 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. Then there is the fact that if you set back the HVAC deeply you have to play catch up and run it longer to get the temperature comfortable when you get home. Deep setbacks only really make sense if you are away for multiple days.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.

author: james_s
author_rank: Super Contributor
timestamp: October 31, 2021, 01:57:18 am
content: Quote from: Ed.Kloonk on October 30, 2021, 08:03:20 pmDisasters 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.

author: station240
author_rank: Unknown
timestamp: October 31, 2021, 04:30:13 am
content: 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.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 31, 2021, 05:17:23 am
content: Quote from: james_s on October 31, 2021, 01:47:49 amYou could only heat or cool the room they're in.QuoteIt 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.

author: Someone
author_rank: Super Contributor
timestamp: October 31, 2021, 11:32:33 am
content: Quote from: station240 on October 31, 2021, 04:30:13 amI 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.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 31, 2021, 11:56:11 am
content: Quote from: james_s on October 31, 2021, 01:57:18 amYes, and often the best mitigation strategies are very simple and low-cost. For example, in Texas, owning some warm clothesjust in caseeven though they consume 2 sq ft of valuable closet space.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 31, 2021, 12:04:03 pm
content: NiHaoMike's ice storage has the problem of mechanical complexity, including how the ice is separated from the evaporator coil, then transferred into insulated storage, and so on.But if you can accept lower storage energy density, forget about utilizing the latent heat and only use sensible heat, i.e., go for liquid water. It has a long and very successful track record of being used for thermal energy storage, and energy can be trivially transferred with water pumps. It's almost too easy.But yeah, for cooling (or for high-COP heating), the dT can't be much (say 10K) which is an energy density sacrifice. Gravimetric energy density is close to that of lead acid batteries (some 20Wh/kg actual), and volumetric even worse. But whenever you have excess space in your basement, i.e., don't live in some big city with expensive land cost, why the heck not.I do exactly that, store heating energy in water at quite low dT, but clearly my 1200liter tank is too small for what I really want to do. What's actually needed is in order of 5m^3. This translates into approx. 2-3m^2 of hopefully not too valuable area in your basement.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 31, 2021, 01:12:39 pm
content: Quote from: Siwastaja on October 31, 2021, 12:04:03 pmJust put a loop of copper tubing in the tank, problem solved.

author: Marco
author_rank: Super Contributor
timestamp: October 31, 2021, 05:15:00 pm
content: Quote from: Siwastaja on October 31, 2021, 12:04:03 pmFor hydronic not all that much. Instead of directly pumping through your storage tank, the heat pump has its own propylene glycol loop with two heat exchangers in the tank, one for each loop. Need 1 extra pump.Just make the surface area on the heat exchanger large enough and finely enough distributed you can freeze the water in place. Dealing with the expansion will take a bit of engineering.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 31, 2021, 06:11:18 pm
content: Freezing water is well known to burst pipes so I guess it would be non-trivial dealing with that.The glycol solution inside the pipe won't freeze, but the water in tank would need to freeze; result is the same. I'm suspicious how to handle that force. Strong thick walled pipes could do it. Then the tank walls must cope with the force as well. OK, make it out of 10mm thick steel and weld reinforcements.But no matter how strong you make everything, the expanding ice has to go somewhere. I guess when the structures are strong enough, then the ice just crushes itself. OK, let's call that sorted out.But then again ice has worse thermal conductivity than liquid water (seems to be about one quarter) and even more importantly, within ice, natural or forced convection becomes impossible. So the ice first forms on the tubing, but as the layer thickness increases, power transfer worsens, or the transfer liquid inside pipes must be made even colder to compensate, worsening the COP.This necessitates that the whole storage tank must be full of that strong pipework, because ice can be only generated within short distance (maybe a centimeter / half an inch?) of the pipe with good efficiency or rate (power). You can see this effect in action by noticing how about an inch of ice that has formed on the evaporator of a refrigerator already decreases the efficiency of the unit to the point it's constantly operating and still temperature inside starts to rise.You can't use traditional expansion tanks either.I just can't see how this is easy or trivial. I'm not saying it's impossible, though. Great engineering challenge.And the prize is high if you can do it, at 334 kJ/kg ~= 0.1kWh/kg = 90 kWh/1000kg it would allow quite nice energy density compared to just using sensible heat; with cooling you would be limited to just dT=10degC which means 42kJ/kg = 12kWh/1000kg.And to give you an idea how much force freezing water can generate, that's how exposed bedrock erodes in cold climates. Water seeps in tiny gaps and this is strong enough to crack the rock.

author: rstofer
author_rank: Super Contributor
timestamp: October 31, 2021, 06:33:52 pm
content: Quote from: Someone on October 31, 2021, 11:32:33 amOur utility has a scheme for remotely shutting down HVAC units for brief periods when system demand is high. During these brief high demand periods, HVAC compressors are locked out for up to 15 minutes every half hour. The program is voluntary and has some rewards.https://www.pge.com/en_US/residential/save-energy-money/savings-solutions-and-rebates/smart-ac/program-faq/smartac-program-faq.page

author: james_s
author_rank: Super Contributor
timestamp: November 01, 2021, 07:41:30 am
content: How do they stop people from simply bypassing the thing once they've signed up to get the benefits? Air conditioners are simple enough devices I don't see what they could do to lock out the compressor that wouldn't be trivial to bypass. You can even push in the contactor with a screwdriver and the compressor will start up.

author: Marco
author_rank: Super Contributor
timestamp: November 01, 2021, 08:25:58 am
content: Quote from: Siwastaja on October 31, 2021, 06:11:18 pmThere's already systems out there for non residential use, so I assume they solved it.You could put lots of air filled flexible hoses in the water volume and along the container wall (no need for steel then) to give the pressure somewhere to go perhaps?

author: Bassman59
author_rank: Super Contributor
timestamp: November 01, 2021, 08:08:55 pm
content: Quote from: NiHaoMike on October 31, 2021, 05:17:23 amWhere am I going to store this water?

author: bson
author_rank: Unknown
timestamp: November 01, 2021, 08:36:38 pm
content: Of course the grid needs to be upgraded to handle a large number of small power providers. The problem is if you upgrade it people will consume more power, and that's bad. PG&E's profits are decoupled from its energy sales, so it has no incentive to sell more. Just about everyone with an interest in energy conservation are opposed to investing in anything that might cause more energy consumption, regardless of whether it's to charge a Tesla or run a heater. This of course makes sense, because the incremental power for every new Tesla plugged in comes from a fossil-fuel generator somewhere.

author: thm_w
author_rank: Super Contributor
timestamp: November 01, 2021, 11:27:11 pm
content: Quote from: james_s on November 01, 2021, 07:41:30 amWhat stops you from just bypassing your electrical meter and not paying for electricity at all.

author: james_s
author_rank: Super Contributor
timestamp: November 02, 2021, 12:22:56 am
content: Quote from: thm_w on November 01, 2021, 11:27:11 pmThe box is tagged with a special tamper evident seal. Theft of electricity is a serious crime and they have ways of detecting it. I don't think running the AC when it's supposed to be locked out is a crime, certainly it is not theft and I suspect would be much harder to detect. You're still paying for the electricity.

author: bdunham7
author_rank: Super Contributor
timestamp: November 02, 2021, 12:46:14 am
content: Quote from: james_s on November 02, 2021, 12:22:56 amHere in SoCal (or the Bay Area) there are no serious crimes anymore. Just wayward souls crying out for help by shoplifting and driving drunk. I can't prove it, but I suspect that in some places theft of electricity is as rampant as any third world country--and if it isnt', it's only because nobody is smart enough to pull it off.

author: rstofer
author_rank: Super Contributor
timestamp: November 02, 2021, 02:42:52 am
content: Quote from: james_s on November 02, 2021, 12:22:56 amIn terms of the HVAC, the utility could look at the demand on the revenue meter and expect a reduction from not running the compressor. If they didn't see the reduction, they could make a pretty good guess.As to bypassing the revenue meter: The utility has a lot of comparative information. If you 3,000 sf house is using demonstrably less energy than your next door neighbors 3000 sf house, they might start to suspect something.A lot of people have used inductive coupling from overhead HV lines and that too is theft:https://www.industrytap.com/electromagnetic-harvesters-free-lunch-or-theft/1805There's nothing new here, every possible scheme has been tried and detected. The utilities employ some pretty bright folks.

author: rstofer
author_rank: Super Contributor
timestamp: November 02, 2021, 02:45:38 am
content: Quote from: bson on November 01, 2021, 08:36:38 pmYou're overlooking nuclear. There are still 93 operating nuclear reactors in the US. Mostly on the east coast.

author: Someone
author_rank: Super Contributor
timestamp: November 02, 2021, 03:35:53 am
content: Quote from: rstofer on November 02, 2021, 02:45:38 amNuclear, which runs almost perfect capacity factor, no way no how. Its not the excess capacity in the grid sitting idle just waiting for demand, that'd be the coal (seasonal) and hydro or gas (short term) plants.

author: james_s
author_rank: Super Contributor
timestamp: November 02, 2021, 06:00:52 am
content: Quote from: rstofer on November 02, 2021, 02:42:52 amThe energy consumed by my air conditioning is absolutely dwarfed by what the hot tub uses if I fire that up, it doubles my electric bill. A day of air conditioning on a moderately hot day is roughly equivalent to running two loads of laundry through the dryer. I really don't think there would be a useful amount of data in the overall consumption to make an accusation. According to the comparison graph on my bill, my average electricity consumption is dramatically less than most of my neighbors, unless I'm running the hot tub, which I do sporadically depending on the weather and how busy I am.I would argue that inductive coupling from overhead lines is not theft. If it is, then the electromagnetic radiation is trespassing on my property. If somebody doesn't want me to utilize something that's in the air, keep it off of my property. I apply the same logic to radio waves, if someone doesn't want me receiving them and listening, don't transmit them near me.

author: rstofer
author_rank: Super Contributor
timestamp: November 02, 2021, 04:50:14 pm
content: Quote from: james_s on November 02, 2021, 06:00:52 amYou can make that argument, and I am reasonably sure somebody has, but it will come down to them being a public utility and your rights are out the window. Think 'eminent domain'... Sure, only a government agency can invoke it but they can turn it over to whomever they wish - like a public utility.From experience, I can tell you that you don't want to lay wire on the ground under a 115 kV bus works. No, I didn't get hammered but I could see the effect with a non-contact voltage detector.I don't think inductive coupling will be effective at low residential voltages but I can't say I ever tried it.I once had a gas fired hot tub and it could do some serious damage to the utility bill.

author: Bud
author_rank: Super Contributor
timestamp: November 02, 2021, 05:24:21 pm
content: Quote from: rstofer on November 02, 2021, 04:50:14 pmYes i remember an incident where an iPad was stolen and the thief put it in his garage. The owner was able to track down the location using Find my iPad feature , brought the police with them and activated the alarm sound on the iPad over the air to demonstrate to the police that the device was on the property. They busted the thief who then brought trespassing charges in defence that air waves to activate the alarm tresspassed his property. The judge threw that argument out.

author: james_s
author_rank: Super Contributor
timestamp: November 02, 2021, 05:29:43 pm
content: Well that thieve's argument is ridiculous. Obviously it's not feasible to keep radio waves off of a person's property, my only argument there is that if the radio waves are there, I'm within my rights to receive them and listen to the contents. Back in the days of analog cellular phones the cellular companies managed to lobby through a law making it illegal to receive the un-encrypted analog transmissions. All scanners sold were required to have those frequencies locked out but it was usually not hard to unlock them. I have yet to ever see a Radio Shack Pro-2004/2005/2006 scanner that didn't have the cellular mod done. It's ridiculous to make it illegal to receive a signal that is freely in the air.

author: Marco
author_rank: Super Contributor
timestamp: November 02, 2021, 08:08:56 pm
content: Quote from: Bassman59 on November 01, 2021, 08:08:55 pmIsn't everything big over there? American airconditioner heatpumps seem to be the size of an IBC to begin with. Though I agree, if you can't just hide an insulated IBC in a huge yard it will bring considerable costs to bury it. Heatpumps with significant storage make more sense for new buildings and renovations.

author: james_s
author_rank: Super Contributor
timestamp: November 02, 2021, 09:41:53 pm
content: Quote from: Marco on November 02, 2021, 08:08:56 pmThey never used to be, but efficiency mandates combined with the move to R410a refrigerant resulted in MUCH larger units. Traditionally they get the efficiency up by increasing the ratio of coil size to compressor capacity, so a modern 2 ton condensing unit is often bigger than say a 30 year old 4 ton unit. Only recently they've started using things like inverter driven compressors to get the size down, and the Japanese tend to make those narrow units that sit vertically against a wall, those are getting somewhat more common here. Even the biggest units are still smaller than a huge water tank though.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 03, 2021, 12:44:26 am
content: Quote from: rstofer on November 02, 2021, 02:42:52 amAnd what if you wired it to turn off some other large load like a pool pump, dryer, or water heater? (That's assuming there isn't the option to simply get the switch installed on that device in the first place.)

author: james_s
author_rank: Super Contributor
timestamp: November 03, 2021, 06:25:28 am
content: Quote from: NiHaoMike on November 03, 2021, 12:44:26 amWell it would accomplish the same goal wouldn't it? Turning off a large load during times of high demand reduces the demand, doesn't matter whether it's the AC compressor or the clothes dryer.

author: Bassman59
author_rank: Super Contributor
timestamp: November 03, 2021, 07:14:06 pm
content: Quote from: Marco on November 02, 2021, 08:08:56 pmOK, some details. I live in Tucson, so water is at a premium here.And yes, considerable costs will be incurred to dig out the yard and install a tank large enough for this energy-storage purchase. (I do want to install an above-ground rain-water harvesting system.)Also, define "big." The non-wealthy in this country don't have super large yards. I know I don't have a large yard.

author: Marco
author_rank: Super Contributor
timestamp: November 03, 2021, 08:50:21 pm
content: Quote from: Bassman59 on November 03, 2021, 07:14:06 pmThat's still only a couple bucks of water for the IBC. Getting it filled with RO water is probably the same cost in Tucson as anywhere else.