Submitted 4 hours ago by mesamunefire@piefed.social to technology@lemmy.world
How big a solar battery do I need to store *all* my home's electricity? - Terence Eden
Neat breakdown with data + some code.
Basically why the grid exists to begin with. You’re not supposed to be solving these engineering problems on a household budget inside a single home.
You’d be better off simply reducing your consumption or finding alternative methods of power (nat gas or maybe wind or geothermal) during the longer winter nights.
I recently got a solar system and came to the conclusion that if you can sell power back to the grid (not everyone can) for some reasonable percentage of what it costs to buy it, then it will always be worth it to be connected (assuming you already are).
Quite simply, if you have enough solar capacity to get you through the winter (no house is going to have months of battery storage), then you will always be creating far more than you need in the summer. Selling this excess will easily cover any costs associated to being on the grid.
Also at current prices batteries are good for backup power only, it’s always cheaper to sell excess power to the grid in the day and buy it back at night than it is to have battery capacity to get through the night. I worked out it would take 40 years for our battery to pay for itself (assuming the battery kept a constant battery capacity for 40 years…) but less than 10 years for the rest of the system to pay for itself.
We can’t, but we can do net metering, meaning we can offset costs but not get paid. So the best investment is to pay nothing through Dec. 31 and keep costs manageable at the start of the year (net metering ends with the calendar year).
Basically why the grid exists to begin with
Agreed this is the best option. Economy of scales and our consumers wishes should dictate the Grids plan to incorporate cheap energy ( and emergency) storages.
And, also like you said, change your energy life style and insulate your house wherever you can.
I’m very ignorant on this subject, but couldn’t you just sell excess to grid and get it back for a minimal markup? Seems like a good governmemt incentive to even supplement an even exchange program. Scaling things to everyone having their own giant batteries seems like a waste of the existing infrastructure.
I don’t need to get through winter, I just need to get from dusk to when the cheap energy is gone. Currently that’s about 4kwh - or a small portion of my car battery before or recharges on the cheap rate.
battery and solar at the home level is what makes the most sense.
60% of the planet lives between the subtropics and tropics. There is way more than plenty of sunlight hitting our earth to support all of our energy demands.\
Need to wire the whole world. Let’s go.
The most straightforward path to world peace is to increase the global supply of energy to the point of negligibly low prices
BombOmOm@lemmy.world 4 hours ago
O, god, it’s going to be huge. You really can’t do the off-grid thing unless you have enough power production to satiate you over any given 3-day moving window. Trying to store power from summer until winter is going to be too expensive, instead buy more panel.
jubilationtcornpone@sh.itjust.works 20 minutes ago
Holy shit. I think we used that much last month, which is higher than average but not that high for August around here.
Buffalox@lemmy.world 3 hours ago
Seems to me his panel capacity is to small anyway.
We have 11 kWh panels, and yes in the summer we routinely produce 4 times more than we use, and we have a 7.5 kWh battery But November December and January it’s not even close.
In the Winter you can easily have a week with near zero production:
Our Import / export from grid last year:
November 215 / 59 kWh
December 300 15 kWh January 268 / 34 kWh
Despite we have almost 3 times the capacity, and produce more than twice what we use per year, and we have a decent battery and believe it or not, even the shortest day we can produce enough power for a whole 24 hour day if it’s a clear day! But we can also have clouds for 14 days!
But for those months we imported 783 kWh and exported 108 that could have been used with bigger battery. But the net import was still 675 kWh!! For those 3 months, and that’s the minimum size battery we could have managed with, and then we even need 10% extra to compensate for charge/discharge losses.
Minimum 740 kWh battery in our case, despite 3 times as powerful panels.
That means it would require at least the equivalent of 10 high end fully electric car batteries. But also a very hefty inverter, which AFAIK ads about 50% the price of the battery.
PS: Already in February we exported more than we imported.
BombOmOm@lemmy.world 3 hours ago
Damn, those winter numbers would mean a full off-grid really is going to be hard with pure solar. A propane or diesel generator to top off the batteries would probably be required for winter.
BennyInc@feddit.org 4 hours ago
You also lose some energy to heat while charging and discharging. And depending on load profiles, you might not be able to load all of your excess solar power at once (depends on how many Watts the battery can be charged at) or fulfill your power requirement with battery alone (depends on how many Watts your battery can deliver).
CompactFlax@discuss.tchncs.de 4 hours ago
I’m a fan of small scale wind, if there’s climate and space for it. 20hrs a day of a (small) 500w adds up really quickly compared to more panels, especially in grey winter weather. The problem is that there’s a bigger difference between megawatt scale solar vs homeowner scale, and megawatt scale wind vs homeowner scale, so there’s limited investment.
Brkdncr@lemmy.world 3 hours ago
Wind isn’t great small scale. You rarely can get high enough for constant wind energy. They are noisy. They don’t produce a lot. In many or even most cases solar will be better than wind.
I’d go so far as building both sun oriented and a solar “fence” line going north/south to get more non-peak solar before putting up small-scale wind.
Jramskov@feddit.dk 4 hours ago
As is mentioned in the article 😉 What is also mentioned is the fact that battery prices are going down. Soon it seems they’ll be down to $10/kWh!
themurphy@lemmy.ml 4 hours ago
There’s also alot of new battery tech on the way.
There will be a market for batteries at home, and they will exist with the best suitable tech for it - and it’s probably not lithium.
How many years, I dont know. What will it be, and who will do it, no clue. Otherwise my stock portfolio would look better if I knew these things haha.
cygnus@lemmy.ca 4 hours ago
I wish the second-hand battery market were more lively. Using half-worn car battery packs seems optimal for home use.
Valmond@lemmy.world 4 hours ago
Sodium batteries?
BTW that’s the wish for trend line, $10/kWh right?
HowRu68@lemmy.world 3 hours ago
How big a battery would we need in order to be completely self-sufficient?
Exactly. Haven’t read all details of the link,but soI react your comment, and have immersed myself a bit in this earlier.
You need to change your way of thinking and energy usage. Start with your daily energy supply and then change your energy consumption pattern to day time use Then, with for example a dynamic energy contract or if you can spare solar energy, buy or store cheap electricity in your storage ( battery ). The energy management system ( charge / uncharge and which cells) is very important.
Als…realize that battery life is tied to charge cycles and need replacing like every 10 years when talking about the better quality Lithium battery . Soda systems could and maybe used in parallel, if you want more storage, safety and longevity.
It is yet all quite expansive, though imo having a half day reserve ( like 5 -10 kwh) battery, would already create more independence.