18 ms·
People both underestimate and overestimate what PV can do. In summer and around noon, here in western Europe, there is so much PV-electricity produced that it i
by Helmut10001 4y ago
People both underestimate and overestimate what PV can do. In summer and around noon, here in western Europe, there is so much PV-electricity produced that it is _almost_ enough to fulfill all demands. In winter, the amount is like a drop in the desert.
I have built a 30 kWp PV at home 2 years ago - you would think this is quite big, for a private plant. It is not enough. If I want to power a heat pump (with drilled holes), e.g. to cover the heating for the house from November - February, I calculated I would need about 70 to 80 kWp (optimized for winter sun angle, e.g. pretty steep modules at 60° or 70° that relatively produce less in summer, but more in winter).
Now I imagine all the people that buy tiny 5 kWp plants. The only way this would work is collaborative, with buffers at the medium-voltage level.
So the biggest problem is really energy transfer or relocation, between different time's and regions´ needs (winter, summer; night, day; or from different regions worldwide).
.. btw. here's a graphic for the calculation [1]. Blue is an imaginary heating pump electricity consumption over the year, red is the predicted pv production for a 60 kWp plant, where 30 kWp are at 60° angle - calculated with Europe's pvgis tool [2].
[1]: https://ibb.co/WKsHPKX https://ibb.co/WKsHPKX
[2]: https://re.jrc.ec.europa.eu/pvg_tools/en/ https://re.jrc.ec.europa.eu/pvg_tools/en/
- jnsaff2 4y agoWith all due respect, looking at your numbers my hunch is that you need better insulation. I know a person who has about 10kWp installed on a passivhaus here in latitude 59N and says that having a heat pump is overkill for them.
- Helmut10001 4y agoYes, absolutely - the house is a pretty big country side house from 1925, not uncommon in Germany. But (almost) impossible to insulate efficiently. My estimates where €150k to €200k, just for the insulation, windows, and renewed heaters. In comparison, an 'oversized' 70 kWp PV only costs €100k, and also returns some income when not all of the power is used. The parameters widely differ between country and city: In the country, you usually have space (but lack money), in the city, you lack space but can often work with a pretty good income (= build a new, energy optimized house). Every house is different. If I build a new house today, of course this would look different.
- bryanrasmussen 4y agoyeah, there are so many old houses are still sitting around in Europe. My area almost every house was built in the late 1800s. Looks pretty nice, but insulation sucks.
- switch007 4y agoThat estimate seems insane. Was that a “we’re too busy, go away” estimate? How big is the house?
- Helmut10001 4y agoIt is quite a standard 2-generations house (at that 1925 time), 250 m² and two apartments, + a base level with an office. I am not saying that this is the universal standard - but it is _a_ standard that I do see quite often here, especially if you look outside cities, where the turnaround for reconstructon of houses is slower. .. and this was quite thoroughly calculated. I can tear down the house and build a new one, but apart from the waste of resources - building a new one will also cost minimum €200k - so I thought, why not 'oversize' PV, if it only costs €100k and can heat the house without improving on insulation? To emphasize, this conclusion will likely not apply to the majority of people (especially here on HN) because as many have said here, parameters and contexts differ widely.
- swores 4y agoDoes the calculation stay the same looking decades ahead? I'd have guessed that 200k to rip it down & build a new house that has great insulation - or even to just retrofit insulation and other upgrades to the existing building - would be expected to last longer before costing the same amount against to replace (and/or pricey maintenance/insurance of the more expensive PV, aircon etc.). And might therefore work out cheaper when looked at as a 50 year question rather than 1 year one? I don't presume to know more than you, not only don't I know about your specific situation I also know very little about these subjects generally, I'm just curious.
- 4y ago
- dmitriid 4y ago> With all due respect, looking at your numbers my hunch is that you need better insulation. With all due respect these are the kinds of "tiny" details that renewable enthusiasts conveniently forget. Yes, this person's house needs better insulation. As does everybody else's. You can't just wave this away with "your math is wrong". These numbers reflect reality, not wishful thinking.
- dvh 4y agoIn a worst case scenario (no gas, no grid electricity), he could heat only one room instead of entire house.
- stewbrew 4y agoHow is this a tiny detail. We live in a passivhaus. We hardly ever heat. Improving insulation of old houses is an important aspect here. Reducing energy consumption is as important as generating and storing energy.
- JohnHaugeland 4y ago
- stewbrew 4y agoI don't see how this relates to this discussion other than by spamming this subthread.
- JohnHaugeland 4y agoI appreciate that you don't see how a direct answer to your question, where you asked what you don't understand and it was spelled out for you, doesn't relate to the discussion. I agree, your attempt to make the world's energy problems about the way you live personally in a Passivhaus doesn't relate to this discussion. That was kind of my point, as well as the point of several other people who've replied to you so far. You might as well ask why everyone doesn't just live in an igloo. It's because they don't work in the places that most people live, like downtown. And if you try to ask the company "hey, I see that you claim you reduce carbon by 90%, why wouldn't LEED certify you, they only require 30%," the company will quickly change the topic. I'll try it a little differently. "If your solution doesn't work for 99.99% of humans, your solution just doesn't work." No, I wasn't selling anything. This wasn't spam. But, you knew that. I was making a good faith attempt to answer the question you asked.
- ekianjo 4y ago> better insulation better insulation is not cheap and therefore not everyone can afford to do it. Also the same people who want renewables are usually opposed to building new housing so there's that.
- taneq 4y agoIt's not super expensive, really. And this is something that building codes can address - either via the gentle option of requiring all newly built dwellings to be thermally efficient, or the somewhat more assertive route of requiring any home sold to have adequate insulation.
- brtkdotse 4y agoThe actual insulation is stupid cheap when you look at the ROI. However, installing in on an existing house is really tricky and you can cause a lot of moisture related damage if you do it in the wrong way.
- Roritharr 4y agoThe house I live in, like everyone's in my street, is from the late 1800s. Insulating those houses from the outside is very expensive, to the tune of 200k, where the house is worth around 500k in the inflated environment we're in. At the very same time, I haven't found a single insurance company willing to insure the house after insulation for insulation related moisture damage. This makes insulating this house an absurdly bad financial decision, since once you have moisture damage in any part of this material, you can basically demolish most of the walls since it soaks like a sponge. Mind you, I have not started going into the pitfalls of the legality of even touching a house this old in Germany, where you have to deal with "Denkmalschutz". Insulating new construction and retrofitting insulation are two absolutely different things and barely have anything to do with each other from the cost-benefit ratio.
- brtkdotse 4y agoAbsolutely, and the thing about old houses is that they've evolved to keep moisture and ventilation in check without access to modern tech. Modern tech, as you point out, usually makes things worse. My house in Sweden is from the 1950's and I still had to be _very_ mindful when adding insulation. The best thing I've found is cellulose-based insulation, basically shredded newspapers lined with salts and pressed to sheets. The can buffer a lot of moisture without developing mold.
- isoprophlex 4y agoThe catch is that power-to-gas tech described in the article will allow you to store the power produced in summer. Produce excess methane gas in summer, store with existing infrastructure, burn it for baseload/winter.
- m12k 4y agoFrom the article: "Just as converting chemical energy in the form of fuel into electricity endures 45-75% thermodynamic losses, converting electricity back into chemical fuels loses 60-70% of the energy in the process. Converting solar power into natural gas only to burn it in a gas turbine power plant could help with long term seasonal energy storage but is so much less cost competitive than other ways to stabilize electricity supply that we should expect this usage modality in, at most, niche cases."
- jiggywiggy 4y agoIt might be less cost effecient at the moment. But I kinda like the decentralized nature of it.
- Schroedingersat 4y agoIf the chemical fuel can work in a fuel cell, then where it's relevant (high latitudes in winter), you can get 100% efficiency in the chemical->used energy step by using the fuel cell for heating. The electricity->fuel step struggles to heat 50%, which is not a deal breaker compared to other sources. The hard bit is storing hydrogen.
- JohnHaugeland 4y ago> The catch is that power-to-gas tech described in the article isn't real
- cinntaile 4y agoThe Sabatier reaction has been known since 1897. The Wiki article also gives some examples of Power-to-gas systems that were built, so I don't know why you claim it's not real. https://en.m.wikipedia.org/wiki/Sabatier_reaction https://en.m.wikipedia.org/wiki/Sabatier_reaction
- choeger 4y agoI think with 30kWp you should be able to heat enough sand to make it over the winter. It's a matter of space and finding someone to build you that heat storage.
- Helmut10001 4y agoCurrently, it is cheaper though to "sell" the electricity in summer and "buy" it back in winter (even if it is at 10x the price I sold it for). Compared to private long term storage solutions. Most long term electricity storage solutions will yield electricity at prices above 80c/kWh here (even lithium ion is currently around 50 to 70c, if you calculate 10,000 hrs average lifetime of house batteries). And you cannot use lithium ion for long term storage, you would need H2, or heat storage solutions.
- choeger 4y agoSand is heat storage, not electricity storage. Storing heat can be much simpler and much more economical (considering that heat is the majority of your energy consumption).
- guerby 4y agoCurrent consumer friendly rack battery LFP prices are at around 400 EUR/kWh, here an example of a 5.12 kWh for 2100 EUR: https://www.europe.sokbattery.com/product-page/sok-battery-100ah-48v-server-rack-battery https://www.europe.sokbattery.com/product-page/sok-battery-1... These are rated for 6000 cycles to 80% degration, so if we take an average of 90% assuming linear degration we will be able to output 6000 by 0.9 so 5400 kWh for each kWh of battery capacity before the battery reaches 80% of its original capacity. 400 EUR divided by 5400 is 0.074 EUR per kWh out the the battery, an order of magnitude lower than the 0.80 EUR per kWh you quoted. These have low self discharge but capacity prices (price per kWh stored in the battery) are way too high to do seasonal storage. Note: if you DIY the battery it's half the price: 150-200 EUR/kWh at the cell level currently.
- Epa095 4y agoYour calculations are interesting for day to day peak shaving, but as you noted yourself, these batteries are way to expensive for seasonal storage. Depending on the insulation on your house, one of those would maybe contain enough power for 0.3-1 hour of power-use in the winter.
- benevol 4y agoHave you considered https://www.KryonEngine.org https://www.KryonEngine.org ?
- spaniard89277 4y agoWhat im looking at?
- avhon1 4y agoA perpetual motion machine. ("Free Energy" has long been a used as a synonym by those who believe it is imminently possible.)
- the8472 4y ago> I calculated I would need about 70 to 80 kWp (optimized for winter sun angle, e.g. pretty steep modules at 60° or 70° that relatively produce less in summer, but more in winter). I know there are sun-following installations but those need expensive mechanics and control systems. Aren't there middle-ground solutions that can be manually adjusted twice a year?
- Bombthecat 4y agoIf 70 to 80 is enough in winter,I would assume that it is enough in summer?
- walrus01 4y ago70-80 degree tilt will produce a lot more at latitude 45+ from Nov. 1st to end of February, but at the expense of much less production kWh per month during the rest of the year. In an off grid totally battery reliant pv system such as for some telecom applications you design the PV for December, worst month of the year for kWh production. If it will "survive" December and provide enough for the load to run 24x7 then it'll be fine for the rest of the year. At high latitudes this cha mean a 75-80 degree tilt facing south.
- PeterisP 4y agoIt depends on whether the price you're getting for that power is sufficiently different between winter and summer; because if your contract has a fixed price per kWh then optimizing for winter (which gets you a bit more power in winter, but a lot less power in summer - because in summer the "angle multiplier" gets applied to much more sunlight) is a bad decision.
- bartwe 4y agoSounds like the next step should be long-term at-home storage through generation of solid or liquid fuels.
- jonnycomputer 4y agoGiven the increasing duck-curve [https://elements.visualcapitalist.com/the-solar-power-duck-curve-explained/ https://elements.visualcapitalist.com/the-solar-power-duck-c...] of solar energy production, this makes sense to me, economics and efficiency concerns aside.
- nl 4y agoSurely utility level wind power can fill parts of that gap? Utility level solar is much more effective too of course.
- tluyben2 4y agoIn north-west eu maybe, in south-west not so much; I have had solar for 20 years in different houses in the south and it covers more than enough all year round (we are off grid). During the days, summer and winter, you can switch on whatever as it will never run out; during the night it obviously depends on the amount and quality of batteries. I have had 1 moment without power and that was a rare event for that location: snow covering the solar panels.
- pfdietz 4y agoYou're still seeing a large swing in insolation between summer and winter in SW Europe. You can tilt the PV arrays to increase winter production at the expense of summer (and at expense of overall production); did you do that?
- ncmncm 4y agoPlaces without enough sun in the winter, and without enough wind, too, sometimes, will just import power. You might be able to draw down on HVDC transmission lines. But there will also be abundant solar farms in the tropics synthesizing ammonia for export. If the weather prediction says not enough wind, and your tanked ammonia would run low, and you can't book enough transmission line power, you just order a shipment, which will be substantially cheaper than NG, from anybody anywhere. But you will have overbuilt a great deal of cheap solar capacity, because anytime it generates more than you can use, you can synthesize your own ammonia. First you fill your tanks, and then sell the rest. In winter, the overbuild means you burn less of it. In summer, the excess ammonia will find an unlimited market because ammonia is so useful. It is fuel, it is fertilizer, it is refrigerant, it is feedstock for myriad chemical processes.
- pcdoodle 4y agoI had no idea ammonia had such properties, any recommended readings/video?
- Kim_Bruning 4y agohttps://www.oxfordenergy.org/wpcms/wp-content/uploads/2020/11/Ammonia-as-a-storage-solution-for-future-decarbonized-systems-EL-42.pdf https://www.oxfordenergy.org/wpcms/wp-content/uploads/2020/1... Pure hydrogen has some handling difficulties which might be solved by binding it to carbon (eg in Methane: CH_4), or to nitrogen (eg in Ammonia: NH_3). Ammonia production has as an advantage that nitrogen is available in large quantities in the earth's atmosphere (78%), and ammonia production and usage can therefore _theoretically_ be carbon-neutral (and in fact not involve carbon at all, ideally) Methane production has as an advantage that you can produce it using atmospheric carbon capture (pulling CO_2 from the air), which means it could theoretically contribute to reduction of greenhouse gasses. A downside of atmospheric carbon capture is that earth atmosphere CO_2 is fairly low (0.04%) . (note: Atmospheric CO_2 capture is also proposed for Mars ISRU (In-Situ resource utilization), which is one reason why SpaceX is using methane engines for its upcoming generation of (mars) rockets. There's some synergies / extra investments to be had in working on CO2 capture technologies) (note 2: Current modern methane and ammonia production/delivery tend to use fossil hydrocarbons as the hydrogen donor, rather than water electrolysis https://en.wikipedia.org/wiki/Ammonia_production#Modern_ammonia-producing_plants https://en.wikipedia.org/wiki/Ammonia_production#Modern_ammo... )
- ZeroGravitas 4y agoIf you're on a farm, then vertical bi-facial aligned west/east, or even north/south, or some mix, can radically shift the power output as required. https://www.sciencedirect.com/science/article/pii/S2666955222000211 https://www.sciencedirect.com/science/article/pii/S266695522... https://ars.els-cdn.com/content/image/1-s2.0-S2666955222000211-gr6_lrg.jpg https://ars.els-cdn.com/content/image/1-s2.0-S26669552220002... The summer peak drops but the winter rises to compensate. Daily peak is spread out too, which helps match heat pumps that like to run continuously and battery storage can cycle twice per day. Figures for Germany, but Norwegian researchers suggest it has benefits at their latitude too.
- MilaM 4y agoThe question is, if complete energy autonomy is even that desirable. From an economic perspective I think it makes sense to use the grid as a kind of battery. Sell surplus energy to the grid in summer, buy it back in winter (ideally renewable) and let the utilities deal with the headache of balancing supply/demand and storage. Also, solar panel efficiency is still increasing at a steady pace. A gain of 50% compared to the average efficiency of currently sold panels seems to be achievable in a couple of years. 20% vs. 30% could be all you need to improve your calculation.
- rocqua 4y agoWhat I found cool about the synthetic natural gas, is that Europe already has really good seasonal storage of natural gas. Hence the infrastructure is available for summer-time generation of gas using solar abundance that we use in winter for heating. To my mind, it is seasonal load shifting that is Europe's long term energy problem. Winter energy demand has a bottom that needs to be met. We used to ensure this by stockpiling on seasonal scales. Without stockpiling, and with intermittent production, things will get hairy in winter. Put differently, you can turn up a gas plant, but you can't turn up a windmill or a solar panel. That scares me. Batteries and similar technologies are great for daily variation, but their cost per capacity does not allow for practical seasonal storage. For this I imagine we need cheap bulk storage, and can accept low efficiency because we can fill the stockpile with the cheapest excess power.
- throwaways85989 4y agoI think methanol is even a better storage candidate. https://phys.org/news/2022-06-holy-grail-catalysisturning-methane-methanol.html https://phys.org/news/2022-06-holy-grail-catalysisturning-me...
- bufferoverflow 4y agoMethanol is very nasty though. If it leaks, it leaves you blind or dead.
- Robotbeat 4y agoThis is Northern Europe, tho. 95% of the world’s population gets much, much better solar…
- krzyk 4y agoOther places get much more heat, which is not good for solar.
- Robotbeat 4y agoOn the contrary, it's far better suited to providing demand when solar is most available. It's far better than trying to fight the cold using solar. The tiny theoretical efficiency boost from lower temperatures and high sun is virtually irrelevant in comparison (and much more relevant to thermal power plant considerations). Much of the world gets literally twice the sunlight as most of Germany and that's the annual average. When talking about the winter time, the difference can be more like a factor of 5 or more when taking into account heat needs. I fail to see why people use northern Europe as the baseline for their solar arguments when it's clearly a cornercase, given a global perspective.
- krzyk 4y agoMuch of the world lacks what Germany (and Europe in general) has: industry. You can supply industry using solar, because it is needed during the day mostly. Yes, the output in winter is 10x smaller, that's why we need also other power sources (at least until we have a way to store electricity effectively). What's the purpose of solar farm in Sahara? Lack of a need for electricity (except AC, but not many there can afford it) and transferring power over long distances is not effective. For home heating there are other energy sources, not as clean (well maybe except wind, which blows during winter also): coal, gas, oil and nuclear.
- stolsvik 4y agoWasn't the article exactly about this need for a massive over capacity of installed PV, and that it still is possible to do?
- M_bara 4y agoJust wondering, isn’t it viable to have Solar arrays in the Sahara/equator regions and have the power transmitted to temperate zones? Is the transmission the issue? Is it politics? Super conductors? I’d love to know why we can’t have a follow the sun global grid…
- kristianp 4y agoThere is a plan afoot to cable electricity from an Australian solar farm to Singapore, so these things may be in the future: https://suncable.energy/ https://suncable.energy/
- konschubert 4y agoPolitics. Look what's happening to Germany with Russian gas.
- kkfx 4y agoI have a small 5kWp PV at home, with a small lithium storage (8kWh) just to cover my arse in case of outage, since here (French Alps) there is a very big day-night thermal delta it's very good in summer, where at night I just need the VMC in passive mode and A/C only during the day, for the rest it's enough for heating sanitary water almost ONLY from the Sun, winter included, and to run some appliances (dishwasher, washing machine etc) in self-consumption. Doing more is needed for trying to charge an EV from PV during the day, likely the double at minimum, but to heat the house in winter OR: - I need a very expensive battery (60kWh/~30k€ at least just to avoid big daily deep discharge cycles) who might or might not last 10 years with an expensive geothermal heat-pump 15k€ at least; - I need a giant insulated, probably underground for mere easiness of design, pool and PV plant (I do not know how to estimate but surely few swimming pools of water and enough PV to heat it) to store enough heat for the night. Both options are ridiculously expensive especially since they still NOT give autonomy since they can support day-to-day winter IF the Sun shine enough, witch might but also might not happen. Perhaps in a future H₂ from hydrolysis will be on sale to offer a fuel-cell third option, but I imagine it will be even more expensive. So far it's still FAR, FAR, FAR, cheaper using the grid + an emergency wood based heating. Long story short I might accept investing (I'm actually in the planning stage) a 15kWp or so PV for an EV charging (WFH so without daily car usage) but trying more is just money gifted to some company pocket. Oh BTW that's JUST for private homes. We also have public buildings AND industry...
- SergeAx 4y agoHow viable in terms of performance/(cost+trouble) it is to motorize panels to change only horizontal angle, without full tracking?
- Schroedingersat 4y ago> I have built a 30 kWp PV at home 2 years ago - you would think this is quite big, for a private plant. It is not enough. If I want to power a heat pump (with drilled holes), e.g. to cover the heating for the house from November - February, I calculated I would need about 70 to 80 kWp (optimized for winter sun angle, e.g. pretty steep modules at 60° or 70° that relatively produce less in summer, but more in winter). Have you considered a thermal battery? A cubic meter or ten of NaOH solution can store a surprising amount of energy, and can be charged during summer/spring/autumn with simple solar modules consisting of black pipes in glass. Even if you only store half the energy needed for some of December and January, it halves the needed size of modules. Hydrogen electrolysis is also shockingly cheap, if there were some safe, small scale storage this issue would be solved.