Affordable Solar Battery Options: 150-300 kWH Capacity for Your Home

[Home Improvement]

Hi all,

I'm looking for a high capacity battery to store my solar energy. The capacity I'm looking for is between 150 kWH - 300 kWH per unit, just like the battery used in Tesla cars.
I'm planning for a 2.250 KWH system. The average consumption of my house is around 10kWH per day.
with a battery of this capacity, I can store 2 weeks to a month worth of electricity for my house. a nearly absolute independence from the local grid.
The only problem with Tesla is the price.
Is there any cheaper alternative to Tesla?

thanks

 

[mfb]

Batteries are expensive, and two weeks to a month of storage will be extremely expensive no matter where you buy the batteries from. Is there a need for such a huge storage? Would a diesel generator for emergencies work as well?

 

[Home Improvement]

Batteries are expensive, and two weeks to a month of storage will be extremely expensive no matter where you buy the batteries from. Is there a need for such a huge storage? Would a diesel generator for emergencies work as well?

I see.
but a diesel generator would defeat the purpose of my solar system.
better to just use diesel and store drums of diesel fuel.
this is what I'm afraid of, the battery tech is left very far behind the solar panel tech. affordable energy storage just doesn't exist yet

 

[anorlunda]

the battery tech is left very far behind the solar panel tech. affordable energy storage just doesn't exist yet

Yes, that's true. But it is improving fast. Perhaps in 20 years, you'll be able to afford it.

But if you live in a place that allows net metering, you can use the power grid as a practically unlimited capacity battery, and you can do it free with the non-solar power customers paying the costs. That unfairness is part of the reason why some places are terminating the net metering arrangements. If you do have net metering in your area, don't count on it perpetuating.

 

[russ_watters]

I see.
but a diesel generator would defeat the purpose of my solar system.

Your opening post implied getting off the grid was your primary goal; what is "the purpose" that a back-up generator doesn't work for?

 

[Home Improvement]

Your opening post implied getting off the grid was your primary goal; what is "the purpose" that a back-up generator doesn't work for?

in my opening post, I mentioned about independence from the local grid. so, it's not merely as backup. I'm planning to move away from the grid permanently. I'll tap into the grid only in cases of emergency (system broke down, extreme weather with no sun in a long time, etc).
I have looked into backup generator (gasoline, diesel, bio diesel, LNG, LPG, etc), but I came to the conclusion that despite the type of generator, their M&O will always be several times more expensive than local grid. so, the only free energy source is solar, the only investment is the solar system.
the only component that's still a mystery to me is the battery, how much the cost for this to see if it's possible to use solar as the permanent alternative to local grid. so, I'm posting this hoping to hear someone replying like "oh yes, there's this battery by company X, it's got 200 KWH with price tag of only $1000". something like that, but it seems that my worst fear has been confirmed, it's just a dream.

 

[anorlunda]

If cost is your primary concern, then learning to live using less energy is much more effective than batteries or more panels.

My wife and I lived for 12 years off the grid on a sailboat. Some people might say luxury yacht. Our electric consumption was 0.6 kWh per day, of which 80% of that went to refrigeration. We have friends that live in a lovely house on an offshore island in Maine. They have no electric of any kind, but they live a very comfortable life anyhow.

You don't say where you live, but in some places geothermal heating/cooling is very achievable.

 

[russ_watters]

in my opening post, I mentioned about independence from the local grid. so, it's not merely as backup.

No, I meant back-up to the solar system.

I'm planning to move away from the grid permanently. I'll tap into the grid only in cases of emergency (system broke down, extreme weather with no sun in a long time, etc).

Your constraints are confusing. Do you mean literally moving away from the grid or just disconnecting from it? In order to tap-in during emergencies and long-term bad weather you of course need to be connected to the grid. Which begs the question: why bother with storage at all if you can just be net-zero (produce on average just a little more than you use).?

What I really wanted to know is if you had an environmentalism reason for wanting to be off-grid, which might also preclude a gas generator (fossil fuels). So far though I don't really see any reason at all why you are planning to do this. You've kind of said what you want to do, but you haven't said why, so it is difficult to provide guidance to get you where you want to go if we don't know what the constraints are.

I have looked into backup generator (gasoline, diesel, bio diesel, LNG, LPG, etc), but I came to the conclusion that despite the type of generator, their M&O will always be several times more expensive than local grid. so, the only free energy source is solar, the only investment is the solar system. the only component that's still a mystery to me is the battery...

Right: as you are finding out, free energy isn't really free. There very few scenarios where solar energy is cheaper than grid power and even when it is, it is a very long payback (generally 20+) years. It is very difficult to make a case for solar on economic grounds.

However, the best deal for solar is with no battery and net-zero total usage of grid power. And the obvious reason why is that you don't need to buy a battery or any other type of back-up to the solar; "storage" is provided by the grid, on a daily basis.

Next, though, I would consider a 3-tiered system:
-Solar panels
-Small battery; perhaps 30 kWh
-Back-up generator

Depending on your local weather conditions, you can find a sizing of the panels and battery pack where 99 days out of 100 you are covered. For those rare cases when you aren't, you'd just turn on the generator and run it for a few hours to boost the battery charge. The government provides such data:
http://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3/
And I would think a solar integrator would help run the scenarios.

There's likely never going to be a time when the other 120-270 kWh of battery back-up is going to be cheaper than a 3 kW generator.

I'm posting this hoping to hear someone replying like "oh yes, there's this battery by company X, it's got 200 KWH with price tag of only $1000". something like that, but it seems that my worst fear has been confirmed, it's just a dream.

Yes. We're very far away from that being realistic.

The only other scenario I can think of that might help is a plug-in hybrid or electric car that can serve as an additional back-up. I think Tesla has kicked that around, but I don't think it has actually been done yet.

Something else, if you haven't looked into it yet: if you aren't talking about literally moving somewhere where the grid doesn't reach, you will need to check your local codes/regulations regarding disconnecting from the grid either temporarily or permanently. It is possible that neither are legal.

 

[mfb]

At 10 kWh/day, even 500 W to 1 kW from the generator would be sufficient - just enough to keep the house running if the battery is nearly depleted.
It will cost more than using the grid - otherwise we wouldn’t have a grid.

 

[Home Improvement]

If cost is your primary concern, then learning to live using less energy is much more effective than batteries or more panels.

My wife and I lived for 12 years off the grid on a sailboat. Some people might say luxury yacht. Our electric consumption was 0.6 kWh per day, of which 80% of that went to refrigeration. We have friends that live in a lovely house on an offshore island in Maine. They have no electric of any kind, but they live a very comfortable life anyhow.

You don't say where you live, but in some places geothermal heating/cooling is very achievable.

I live in the capital city of Indonesia, Jakarta, so, far from any natural phenomenon like geothermal, etc.

No, I meant back-up to the solar system.

Your constraints are confusing. Do you mean literally moving away from the grid or just disconnecting from it? In order to tap-in during emergencies and long-term bad weather you of course need to be connected to the grid. Which begs the question: why bother with storage at all if you can just be net-zero (produce on average just a little more than you use).?

What I really wanted to know is if you had an environmentalism reason for wanting to be off-grid, which might also preclude a gas generator (fossil fuels). So far though I don't really see any reason at all why you are planning to do this. You've kind of said what you want to do, but you haven't said why, so it is difficult to provide guidance to get you where you want to go if we don't know what the constraints are.

Right: as you are finding out, free energy isn't really free. There very few scenarios where solar energy is cheaper than grid power and even when it is, it is a very long payback (generally 20+) years. It is very difficult to make a case for solar on economic grounds.

However, the best deal for solar is with no battery and net-zero total usage of grid power. And the obvious reason why is that you don't need to buy a battery or any other type of back-up to the solar; "storage" is provided by the grid, on a daily basis.

Next, though, I would consider a 3-tiered system:
-Solar panels
-Small battery; perhaps 30 kWh
-Back-up generator

Depending on your local weather conditions, you can find a sizing of the panels and battery pack where 99 days out of 100 you are covered. For those rare cases when you aren't, you'd just turn on the generator and run it for a few hours to boost the battery charge. The government provides such data:
http://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3/
And I would think a solar integrator would help run the scenarios.

There's likely never going to be a time when the other 120-270 kWh of battery back-up is going to be cheaper than a 3 kW generator.

Yes. We're very far away from that being realistic.

The only other scenario I can think of that might help is a plug-in hybrid or electric car that can serve as an additional back-up. I think Tesla has kicked that around, but I don't think it has actually been done yet.

Something else, if you haven't looked into it yet: if you aren't talking about literally moving somewhere where the grid doesn't reach, you will need to check your local codes/regulations regarding disconnecting from the grid either temporarily or permanently. It is possible that neither are legal.

what I want to achieve is absorb all solar energy during sunny day, save excess energy in battery to power the house at night, so that there will be enough energy until next day harvest. in case it was a cloudy day (during rainy season) and the excess energy is not enough for the night, then tap into local grid. that's about it. the primary objective for me is cost, not environmental reasons. I have also checked the local codes, it's perfectly legal to disconnect from the grid, although I'll use the grid as my fallback. I was really planning to disconnect from the grid completely if the 300 kWh battery exists, but I think we already establish that it's not possible, so, I'm not "moving away" from the grid anymore. you mentioned about 30 kWh battery, is that affordable? and can last long (no need to change every 3 - 5 years)?

 

[rootone]

There are ways to store energy other than batteries.
Water can be pumped uphill, electrolysis can separate water to H2 and O2.
There are solutions using those techniques on industrial scales, but they probably are not scaleable to domestic power.
I think we will see rapid advances in the capacity of batteries, and lower costs in ten or twenty years.

 

[russ_watters]

what I want to achieve is absorb all solar energy during sunny day, save excess energy in battery to power the house at night, so that there will be enough energy until next day harvest. in case it was a cloudy day (during rainy season) and the excess energy is not enough for the night, then tap into local grid. that's about it. the primary objective for me is cost, not environmental reasons.

Well, then disconnecting from the grid is not something that supports your goal. The simple reality is that you spend a lot of money for batteries that you only use very rarely if you want to disconnect from the grid completely. So you are much better off using the grid as your backup.

And anyway, do they not have net zero metering where you are? I don't know your laws/utility rates, so I don't know if solar power is ever viable where you are. It may not be.

you mentioned about 30 kWh battery, is that affordable?

Not really, no -- but it is 90% more affordable than a 150 kWh battery. The cheapest way to do it would probably be to get 60 car batteries or deep cycle marine batteries.

and can last long (no need to change every 3 - 5 years)?

I would think a lead acid battery would last a lot longer than that.

The way you talk, it sounds like you have a vision of what you want; I'm sorry, though; what you want just isn't a reality. It's common for people to think that since the sun provides the energy that solar power is cheap, but it isn't.

I live in the capital city of Indonesia, Jakarta, so, far from any natural phenomenon like geothermal, etc.

@anorlunda is referring to a geothermal heat pump, which is an efficient heating and air conditioning system.

 

[Evanish]

Hello Home Improvement. I've always found this topic interesting precisely because their are no easy answers, or at least no easy answers unless you are able, and willing, to waste huge amount of money on it. Here is a link to an article that really taught me a lot about the problem. Here is a quote from the article that might interest you.

The lesson is that batteries are a can-do solution in terms of fitting into a house envelope. A more practical few-days of storage is that much easier. Although at approximately $150 per kWh of storage, three days of storage for the average American house will cost about $15,000 to cover electricity demand, with the cost recurring every five years or so. But let’s not worry our pretty little heads over mere economic concerns at the moment.

From what I understand the life time of batteries varies a lot based on how they are used and maintained. I'm not too clear on the details, and it seems to very by battery type.

If you are good at making things, and have lot of wood, I've heard about wood gasifiers to power generators. Gasifiers use wood to create a flammable mixture that a generator can run on without gasoline.



Hopefully some of this is helpful to you.

 

[Home Improvement]

@russ_watters I've checked about net metering a year ago with the local grid authorities, but their response is funny --> "You got to build the whole solar system first, then we'll survey your system and decide if we'll allow net metering for you". not sure if that's how it works everywhere, but that's just weird for me. so, I spent all the money and time and effort to build the system, and then they say no, this suddenly becomes a glorified science project. another downside with net metering is that I'll still experience blackout if the grid is down at night. as for the 30 kWh batt is actually a bunch of car batteries connected together, well, let's just say that puts the final nail in my imaginary solar system's coffin.
I guess we can agree that the weak link in any solar system is the energy storage part (battery). so, solar panels are not appetizing for now (at least for people whose only reason to move to solar is saving money, like me), at least until there's a major breakthrough in battery tech.
@Evanish the gasifier seems like a lot of money and effort, will learn more about it, especially the ROI and M&O against the amount of money it can generate. thanks
@anorlunda thanks to @russ_watters seems that I misunderstood your geothermal post. I'll also check out that geothermal pump

 

[Ken Fabos]

Hi all,

I'm looking for a high capacity battery to store my solar energy. The capacity I'm looking for is between 150 kWH - 300 kWH per unit, just like the battery used in Tesla cars.
I'm planning for a 2.250 KWH system. The average consumption of my house is around 10kWH per day.
with a battery of this capacity, I can store 2 weeks to a month worth of electricity for my house. a nearly absolute independence from the local grid.
The only problem with Tesla is the price.
Is there any cheaper alternative to Tesla?

thanks

I suggest you add more solar panels, say 5 kW or as much as you can fit (I assume 2.25 KWH should be kW - kWh would mean 2.25 kW for one hour) rather than rely on very large amounts of storage. You live in the Tropics - yes you will get periods of overcast and rain during the monsoon season but modern solar panels do produce power in low light conditions and more panels will both increase the total output during low light conditions as well as take advantage of those periods when cloud cover is not so dense for battery charging. It takes very heavy cloud and rain conditions to reduce output below 10% of rated maximum.

Such a large amount of storage seems excessive to achieve independence from the grid, especially if you can exercise some control over your usage during periods when solar is less abundant. Even 3 full days of storage sounds excessive. As suggested, backup generators are effective and should not be required very often.

 

[mfb]

The discussion about solar panel prices is now in a separate thread.

 

[dnyberg2]

I was the director of engineering for iCel Systems a Solar power storage company. Our primary product was a Lithium Ion storage battery expressly engineered for solar storage! It was a 1KWh battery and it was scalable. It used 96 of the the very common 18650 cells from Panasonic. The MSRP for each battery pack was about $1500 each! These elements were planned to be expanded to ship container size with all the control and monitoring smarts needed to keep them safe. You're talking about a lifespan of perhaps 10 to 15 years and then you have to replace all the cells because the chemical material in the batteries will be exhausted and spent. Nowadays, cheap cells from China are $50 per 100. Once you get all the electronics in place, cell replacement and system maintenance at the end of the original life span could be staggered to run several hundred dollars a month with a system that size until all the cells were replaced. It would be a full time job even with a computer helping.

 

[Blank_Stare]

All I can add about battery costs, and battery life can be summed up in two words: "Edison Battery".

They are NOT cheap, but have been know to be in continuous service for as long as 50 years, by some reports. They are huge, heavy, and expensive, but for many of us, would be a one-time expense on a product that would out-live us. This is a solution where you are not concerned about money, but rather, want a lifetime solution for your private compound that you don't have to worry about replacing after society breaks down, and batteries are no longer being manufactured. Yeah, I went there - this is the Prepper's wet-dream of batteries. (I am not a Prepper, but I did have breakfast at some fancy hotel the other day...)

I'll let you google the details...