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Selling solar back to the grid has one major problem that, fortunately, doesn't plague windmill installations: The Duck Curve [1]. The problem is that peak ene
by coryfklein 9y ago
Selling solar back to the grid has one major problem that, fortunately, doesn't plague windmill installations: The Duck Curve [1].
The problem is that peak energy usage now occurs after sunset. So no matter how many solar panels you stack on your home, around 6-7 PM the coal, oil, and gas power plants all have to spin up to their max capacity. Your solar panels are new less likely to _replace_ a coal power plant, although they do change how many hours a day it runs.
Unfortunately for the power companies, running a coal power plant for 3 hours a day costs just about as much as running it for 8 hours a day. This leads to the power companies naturally feeling rather sour about being forced to credit residents for the power they supply to the grid during low-demand hours. Their costs are staying about the same, but now their revenue stream goes down.
In some regions (Utah/Idaho/Colorado is the one I'm aware of) these power companies are now negotiating with governments for lower and lower solar credits for these kinds of residents and they're winning because the abundance of solar power at mid-day is legitimately creating an oversupply, thus making that energy worth less and less.
I see this causing problems for many of my neighbors, who had solar sales reps factoring in energy buy-back rates from 2016 into 10-year loans models to pay for the solar panels. Soon the energy the power companies pay my neighbors is going to offset their panel loans less and less, which may result in a reversal of the economics that led to them buying the panels in the first place.
[1] https://en.wikipedia.org/wiki/Duck_curve https://en.wikipedia.org/wiki/Duck_curve
- vosper 9y agoThere was a very interesting article about hydrogen fuel cell cars posted on HN the other day, one of the things they mention is that excess energy could readily be diverted to hydrogen manufacture. http://www.thedrive.com/tech/14431/are-hydrogen-cars-the-next-big-thing-again http://www.thedrive.com/tech/14431/are-hydrogen-cars-the-nex...
- fulafel 9y agoWhen power gets more expensive in the evenings, a lot of heating/cooling/charging loads may shift in time. Also, hvdc grids let you transmit over a couple of timezones. (And wind does not have the problem the first place, obviously)
- ams6110 9y agoIf possible, but it may only get worse. If EVs become more prevalent, it will only increase the evening demand as most people will charge when they get home from work. Sure, maybe with timers you can shift that to midnight or something, but it's still happening at a time when Solar adds nothing. You can't just toss out something like HVDC grids as a quick solution. That kind of infrastructure takes decades to build out.
- fulafel 9y agoI'm not sure why you discount charging during the day. Most EVs don't empty their battery by 6pm and require a full charge at 8am.
- blang 9y agoI'm guessing because there is less availability for charging during the day when you are at work, rather than at night when you are home.
- coryfklein 9y agoHow long to EVs take to charge? Should be pretty simple to put a time delay into the charger to _begin_ charging around 2 AM when energy usage has gone back down again.
- Brakenshire 9y agoThis is already happening, in a more sophisticated way: https://www.autocar.co.uk/car-news/industry/nissan-and-uk-government-lead-uk%E2%80%99s-biggest-vehicle-grid-project https://www.autocar.co.uk/car-news/industry/nissan-and-uk-go... Consumers are offered reduced cost tariffs to simply request a charging level by a certain time tomorrow morning, and in the meantime let the grid take or receive electricity as it wishes.
- jonas21 9y agoEVs can also be part of the solution with demand-based pricing. Instead of charging when they got home from work, people could start dumping excess energy from the battery into the grid during the peak and charge overnight at lower-demand times.
- IpV8 9y agoCalifornia and Hawaii have already implemented price curves that make purchasing solar + storage viable for homeowners. As more states adopt these policies and more homeowners adopt batteries the duck curve can be solved. Also battery storage gives the added benefit of not needing a gas generator when the grid goes down if you have an islanding system!
- coryfklein 9y agoHow does one implement a price curve? By supply & demand, it is just the result of energy production + energy usage. Are you saying that California has somehow made energy scarce during the day or are you talking about price manipulation?
- IpV8 9y agoThe price of buying/selling to/from the grid is different at different times of the day. Artificially set by the utility. Different utilities have different rules. In some you can take advantage of the arbitrage if you have a battery; buying during the day and selling in the evenings. Exe here is San Diego's pricing from the perspective of consumption only: https://www.sdge.com/residential/pricing-plans/about-our-pricing-plans/time-use-plans https://www.sdge.com/residential/pricing-plans/about-our-pri...
- ProblemFactory 9y agoYou could skip the price models/curves, and just go with a real-time exchange. Something like NordPool (https://www.nordpoolspot.com/ https://www.nordpoolspot.com/), which trades electricity between UK, Germany, Nordics and Baltics. Electricity price on the market changes every hour depending on production and consumption. You can trade on it like on any futures market, or as an active participant if you had a large battery or transmission cables. Local utilities here offer "market price + 5% margin" plans to home consumers if you want to take advantage of the lows to adjust your usage.
- digikata 9y agoIt only takes a little bit of battery capacity to shift the duck curve, and is a nice lead into the market ramping up volume to cover more and more capacity and time. It's also an power time-cost arbitration model which is very comprehensible to financial backers.
- protonfish 9y agoI would think this could be fixed simply by cooling the home lower than optimal at peak solar, plus some thermal storage.
- Brakenshire 9y agoYou just have to reduce the cost of electricity in the middle of the day and the market will find 1000 ways to make use of it. Another example is that large scale electric car charging stations already use batteries to trickle charge through the day, and then dump electricity when a car needs it. If there are big cost differences in electricity through the day, it strengthens their business model to do arbitrage, charging more at cheap times.
- antisthenes 9y agoAs another comment pointed out in the thread, Germany's aluminum manufacturers are already taking advantage of negative energy prices and scaling production up and down at least 25% during peak energy producing hours. Residential users and smaller companies will eventually find ways to make use of such energy in a similar way.
- stcredzero 9y ago* This leads to the power companies naturally feeling rather sour about being forced to credit residents for the power they supply to the grid during low-demand hours. Their costs are staying about the same, but now their revenue stream goes down.* Time to get rid of coal? What the Duck Curve indicates to me, is that California's grad-scale solar really should be located about 6 hours time difference to the west. How about ocean solar farms located in the plastic laden mid-Pacific gyre? They could be equipped with plastic harvesting equipment.
- CapitalistCartr 9y agoOperating a power plant in the middle of the World's largest ocean, then transmitting the power 4500+ miles (7000+ km) across that ocean would be one of the World's major engineering undertakings, and vastly more expensive than any current method of generating electricity.
- magduf 9y agoAgreed. The ocean is just too deep there. I have a better idea for a megaproject: build a dam across the Strait of Gibraltar, and lower the water level of the Mediterranean. You could get an enormous amount of power from a hydroelectric dam in this location (and later another one near Sicily, after the Mediterranean's level is lowered), plus you'd have a huge amount of new land in the area.
- coryfklein 9y agoQueue the next crypto fancy: Gibraltarcoin! Decentralized electricity monetization transfer something something profit.
- skookumchuck 9y agoWould you want to live below sea level and trust the dam? Not me.
- magduf 9y ago
- pkulak 9y agoYou need a surprisingly small battery to shift use a mere 4 hours. This is why we need market rates for power, for everyone. If I have a bunch of panels and my power is worthless at 2pm, that's fine. A small battery system will pay for itself quickly if that power is worth peak at 6pm. Or maybe I set my car to charge in the early afternoon? Maybe when I install my system, I put my panels facing West instead of south?
- coryfklein 9y agoCan you quote costs here? How much will it cost me to install a battery that lets me come home from work, turn on the air conditioner for 3-4 hours, run 2 loads through my washer and dryer (cause I have 3 kids), do a load of dishes, all while running the water heater, lights, etc? Does a single $4,000 power-wall do that? And if it is merely saving me the cost differential from electricity at noon and electricity at 6pm, is it going to pay itself off in less than 15 years?
- antisthenes 9y agoIt would be more efficient to cool the home while you're not there than to turn on AC immediately after you come home from work in a hot home. > run 2 loads through my washer and dryer (cause I have 3 kids) Surely you don't run 2 loads through your washer and dryer _EVERY_ day, do you? Do your children change clothes every 2 hours? Do you change bedding and towels every day? Point being, I can come up with incredibly inefficient and wasteful scenarios too and then say "well, it doesn't serve my needs either, see!" Shifting energy usage patterns is just as much part of being green as is generating energy in a renewable way. Just because you can come up with a scenario that isn't 100% addressed by that, doesn't mean it's not worth doing in aggregate.
- coryfklein 9y ago> Surely you don't run 2 loads through your washer and dryer _EVERY_ day, do you? No, but I need to be able to _any_ day, and honestly for us doing 2 loads a day happens very often - it's not an edge case for us. If you're befuddled as to how that is possible, join the club. As for shifting our day's schedule around electricity rates, good luck bringing that idea up with my wife.
- magduf 9y ago>The problem is that peak energy usage now occurs after sunset. So no matter how many solar panels you stack on your home, around 6-7 PM the coal, oil, and gas power plants all have to spin up to their max capacity. Where are you getting this assumption from? In hot climates like Arizona, peak energy usage during the summer months is in the afternoon, not the evening. When it's 115 degrees outside, that's when everyone's A/C is running at full capacity. It gets cooler in the evening and A/C usage goes down then.
- lelandbatey 9y agoThe claim that energy usage peaks after sunset comes from the diagram[0] in the OP's link[1]. In the diagram, you can see that solar power peaked at around 3pm on the graphed day, then declined to near-zero by 6pm. Meanwhile, the total load rose steadily throughout the day, peaking at about 9pm before declining. [0] - https://en.wikipedia.org/wiki/File:Duck_Curve_CA-ISO_2016-10-22.agr.png https://en.wikipedia.org/wiki/File:Duck_Curve_CA-ISO_2016-10... [1] - https://en.wikipedia.org/wiki/Duck_curve https://en.wikipedia.org/wiki/Duck_curve
- magduf 9y agoI'd like to see what the curve looks like for southern Arizona and also southern Nevada. California (at least in the populated parts) isn't remotely as hot as either of those places.
- jzl 9y agoI think the duck curve is more about residential usage rather than overall grid usage. And this conversation is about home solar installations rather than commercial ones in offices and places of work.
- sharpercoder 9y agoThe market should be able to handle this. Thus, the government should create the curcumstances this can occur, which means in practice that timeslot-based tarifs should be enabled.
- skookumchuck 9y agoThe solution is straightforward - lower consumer electricity rates when power is cheap, and raise them when it is expensive. Consumers will naturally shift the elastic part of their electric demand to when power is cheap. For example, charging the car when power is cheap.
- syrrim 9y agoIf only consumers were so rational.
- photojosh 9y agoLaziness and complacency is the main hurdle you need to overcome. It needs to be automated. Hey, this AC will cool your house and save you $$$. Hey, turn on this automatic switch and your car will save you $$$.
- msisk6 9y agoYep. Here in Texas we have an open energy market and in most areas you get to choose your energy provider and an array of plans. One of my co-works with a Tesla got a plan where electricity is free at night. He cranks the AC during the night and charges the car and ends up paying around $40 a month. Not bad.