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Is it possible to harvest and store enough solar in summer to carry you through winter?

Gueyog8a7

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Like how we grow crops in summer to take us through winter can the same be done for solar or do batteries not hold charge for long enough for it to be feasible?

I know you could do what my mum does with the solar on her roof and sell solar back to the grid and buy that back again but that does not apply here as I am talking about self sufficiency.
 
Sure, it's possible it'd be ridiculously expensive. Just look at your power usage over the time period you want to run exclusively off batteries. Divide that by that total kilowatt hours by 5, and that's roughly how many 48v rackmount batteries you need to buy. Each of those will cost around 1200-1500 once you add in racks and wire maybe a bit more.

So I used around 600 kilowatt hours last month. So, 600/5=120. So I'd need 120 48v (51.2v in reality) server rack batterys if I wanted to run exclusively off batteries for a month, not counting for inverter losses, but close enough. that'd cost at minimum 1200 usd * 120=144,000 usd before taxes. that's for 1 house for 1 month.
 
Like how we grow crops in summer to take us through winter can the same be done for solar or do batteries not hold charge for long enough for it to be feasible?

I know you could do what my mum does with the solar on her roof and sell solar back to the grid and buy that back again but that does not apply here as I am talking about self sufficiency.
yes but not for the whole winter, you basically store up enough for two or three days of use, and recharge the battery pack when you have good sun.

My cabin has a 500 a/h battery pack and currently i have 5600 watts of panels recharging them (i have more that I have pulled while I reconfigure my panels.) this is enough for one refrigerator, one freezer, one septic tank bubbler, all lights for the house as well as my powering all the lights and single phase tools in my shop.

is this enough for your house? you would need to do an energy audit of your house to find out how much you use on a daily basis over the course of a month or two during the winter (worst possible conditions for solar) and then design your system accordingly. you would size it to power the house for a minimum of 3-4 days without solar input. this allows for days when you your panels output are lower than normal. such as when you have snow on the panels, or two to three days of heavy rain. if your area gets very heavy rain or very heavy snow for more than two to three days at a time, you might need to size your bank, and solar panels larger to accommodate this.
 
Don't forget about the heating power required to keep the lifepo4 battery at operating temperature. Need to factor this too.
Lithium plating caused by low temperature = permanent damage.
 
I can’t think of anything that would be affordable.

If you had the land and elevation, you could use excess energy to pump water, uphill. Then later use that to drive a generator. There are also methods to store heat in a mass like sand.

if you have land again, could grow vegetation that you would convert into a type of bio diesel. Or even burn wood to generate electricity.
 
The person that said, "Move to the equator" isn't all that far off, frankly. From a practical perspective, one cannot store enough solar energy to last from one season to the next for use over any reasonable period of time, as the cost of the storage medium (e.g., batteries) would be too great. I didn't take their answer as being anything more than an amusing way to call that out, although others took it differently. The bottom line is that this isn't like growing vegetables in the summer and then canning or drying the resource until winter. The most almost anyone can afford to store is about 3-5 days of electric use (perhaps 7 at most).
 
My solution for the winter blues is to have a ridiculous amount of solar panel capacity. I currently disconnect 3 arrays in the summer. I can still eke out 1000 watts on cloudy/snowy days sometimes for a few hours. Panels are cheap and I have the land. I actually don’t have that much storage capacity (relative to solar)
 
the OP wrote this question in a naïve way that I think shows his or her general lack of knowledge. as such I addressed it as it should have been from the standpoint of storing enough for short periods of time between good harvesting of solar.

I agree that storing enough for a whole winter would be impossible with what we have available, but I am not convinced that this was the OP's question.

to the OP if this was your question (storing for an entire winter) then no there is no feasible way, the only feasible way is the method I outlined in my post, which is what everybody in the offgrid market does.
 
Don't forget about the heating power required to keep the lifepo4 battery at operating temperature. Need to factor this too.
Lithium plating caused by low temperature = permanent damage.
yes I have a 3p16s bank that burns 15 watts continuously to keep the battery bank at 15~20°c while the outside weather is -10°c. not really as much as one might think for a large-ish bank. this boils down to the mass of the bank itself, and the insulation you put around it.

once again part of the overall strategy when you design and implement a system.
 
The person that said, "Move to the equator" isn't all that far off, frankly. From a practical perspective, one cannot store enough solar energy to last from one season to the next for use over any reasonable period of time, as the cost of the storage medium (e.g., batteries) would be too great. I didn't take their answer as being anything more than an amusing way to call that out, although others took it differently. The bottom line is that this isn't like growing vegetables in the summer and then canning or drying the resource until winter. The most almost anyone can afford to store is about 3-5 days of electric use (perhaps 7 at most).
yes I am currently at three days, and will hit eight to nine days with the install and implementation of my new bank(s) this month. not sure of which vein the OP was asking the question as it is not worded as well as it could be. I think the whole analogy to gardening threw some folks off.
 
My solution for the winter blues is to have a ridiculous amount of solar panel capacity. I currently disconnect 3 arrays in the summer. I can still eke out 1000 watts on cloudy/snowy days sometimes for a few hours. Panels are cheap and I have the land. I actually don’t have that much storage capacity (relative to solar)
I am aiming for both, and in the summer I will heat water...lots of it, with the excess from the panels.
 
If you can use the excess Summer time solar to create a fuel for winter it can be done. On my place this is done by growing trees. In the Winter the harvested wood fuels my stove which keeps me warm. I could build a wood powered steam generator for electricity but the thought of keeping it operating would involve too much effort.
 
Like how we grow crops in summer to take us through winter can the same be done for solar
Edit - reviewed and fixed due to cal vs kcal error.

The reason we don't store energy overwinter like we store food is that there is a 10x difference in daily needs of food compared to electricity. We need about 2,500 watt hours per day of food, but our houses consume around 29,000 watt hours per day of electricity.

Food:
A laboratory standard human requires 2,000 kcalories per day input to live and work. Less if they don't move much and are in a temperate climate, more if they perform a lot of physical labor and are in a cold environment.

Assuming winter is 4 months long, then 120 days of food are needed, or about 240,000 kcalories. That's 150lb of rice (assuming 1,600 kcalories per dry pound), so you can meet the caloric needs of 1 adult human with a small stack of three 50lb bags of rice, or about $160*.

There are 860 calories in one watt hour. Humans need under 2,500 watt hours per day.

So that entire winter's worth of rice represents 279,000 watt hours of energy. This represents less than $50 of electricity depending on your local utility rate.

Animals (ie, humans) and plants are very efficient at energy conversion.

Electricity:
The average household in the US consumes around 886kWH per month. So over a four month winter you'd need 3,544,000 watt hours stored up, or 3.5MWH.

Low cost residential battery storage is around $100/kwh. So you'd need around $350k just for the batteries. You'd then need to collect 3.5MWH over the other 8 months of the year, on top of your residential consumption, either by buying electricity (charging at night when rates are low, for instance) or by building a 15kWH to 30kwh solar array, depending on your location and solar insolation. At $0.50 per kw, the solar would cost around $8k to $16k. You'd need to pay more for wiring, inverters, charge controllers, mounts, battery storage room, etc.

Newer technologies promise grid scale solar energy storage as low as $132/MWH (iron oxide batteries, Bezos backed research) but those are 1) a long way off, 2) new research so are unlikely to meet stated goals, and 3) prices assuming a utility is buying hundreds of GWH of storage, not just a few MWH.

That 3.5MWH of battery storage is comparable to 3 billion kcalories, or about 3.8 years of food energy the average human needs.

Conclusion:
It would be expensive, prohibitively so for most people, to store enough electricity to last all winter, since we consume 10 times more energy as electricity than we consume as food, and food, as a basic need, is very cheap compared to electrical storage and generation.

Conversely, it takes a space, time, water, and effort to grow and harvest 150lb of rice. About 7,400lb of rice is harvested per acre in intensive rice farm operations, so about 800 square feet of rice in fertile soil, along with nutrients, water, weeding (usually chemical), etc will supply enough energy for one human over the winter, or about 2,400 square feet for the whole year. That's enough space for a 23kw solar array, which would meet the electrical needs of a human for a year, assuming a method of storage is managed.

So there's a lot of energy just being thrown around and wasted in electricity, but our solar panels are more efficient than growing crops, there's just that little problem of feeding humans electricity.

This all changes if we lower our energy consumption. Smaller dwellings, underground with great nearly perfect insulation, lower light levels, more raw foods (ie, reduce heat required for cooking), no AC, smaller fridges and freezers, etc, etc, etc. But even then, a large TV consumes in an hour what a human needs in one winter, so you'd have to be very, very frugal with energy to reduce the 10:1 ratio between electrical consumption and food consumption enough to be practical.

*Note that the rice requires at least soaking if not cooking to get all the calories available out of it, and this water and heat represent a not insignificant amount of energy as well.
 
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I agree that storing enough for a whole winter would be impossible with what we have available, but I am not convinced that this was the OP's question.
Most likely impossible for a home owner even in the future.
Cold is the absence of Energy. Any kind of energy being stored is experiencing Entropy and is being reduced by the cold. The expense for the insulation and it's overall effectiveness vs Price would make this a NASA kind of project.
 
Like how we grow crops in summer to take us through winter can the same be done for solar or do batteries not hold charge for long enough for it to be feasible?

I know you could do what my mum does with the solar on her roof and sell solar back to the grid and buy that back again but that does not apply here as I am talking about self sufficiency.
We talked about this not long ago.
Best you can do is try to save enough to cover a few days of bad weather.

It’s just more economic to have more panels for the limited production time available.

If you needed say 2000kWh to get through just December your talking about 400 server rack batteries or 133 DIY batteries.

Just better off to buy more panels.
 
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