Are you researching batteries for living off the grid? If so, you know there’s a lot of information available online.
Yet most of it assumes the reader has some knowledge of batteries. If you don’t, here’s a quick overview of battery bank basics for an off-grid home.
What is a Battery Bank?
Estimated reading time: 8 minutes
In simple terms, a battery bank is just a place to store energy that you've acquired through the use of generators, solar power, wind power, or even aqua power. Our battery bank plays an important role as part of our off grid home system.
For clarity, aqua power is not “Aquaman”. It is energy generated through the use of a water turbine, a topic for a different article.
A battery bank is an appropriate term since it's like banking. You literally save “energy” for a rainy day. The next question to consider is: “Do I really need a battery bank?”
The answer, of course, is not so simple and we will rely on a tried and true lawyer's response: it depends.
Batteries for Living Off The Grid: Why a Battery Bank is Best
The real advantage with a battery bank occurs when you’re off the grid and want to have power available on cloudy days, nighttime, etc. Yet you don't want to run a generator 24/7.
The larger the battery bank, the more power you can store. This allows you to run longer without the need to replenish your power. And this is an important consideration when it comes to batteries for living off the grid.
Do you want to run appliances such as a washing machine or dishwasher in your off grid home in the middle of winter? If so, you'll depend on those batteries.
The dilemma you face is that very few areas have a consistent balance of sunshine/nightfall/clear skies/cloudy skies/comfortable temperature day after day, month after month, and year after year. If they did, it would be easier to establish a system that has a good balance of available power.
Related: Generators for Beginners
Planning an Off-Grid Battery System
To begin with, there are different types of batteries, voltages, amperage, and costs to consider when planning your system. Since batteries aren't cheap, the ideal situation is to find a balance between your average usage and what type of energy source you have.
For example, if you have access to hydro through a local utility company, their energy is usually less expensive than any power you can generate. So if your sole interest is from a financial perspective, it is prudent to consider keeping that power source.
Tip: Add "battery maintenance" to your Fall Homestead Checklist in your Seasonal Homestead Checklists. That way, they'll be in tip-top shape when you need them.
Best Batteries for Living Off The Grid
There are different types of batteries to consider. It’s important to take your budget and off grid costs into account as well as the time you want to spend maintaining your off-grid battery bank.
In the lead-acid category, there are generally three types of batteries: flooded, absorbent glass mat (AGM), and gel batteries.
Flooded batteries are maintainable and have to be checked fairly regularly to ensure the water levels are correct and the plates remain submerged.
The other two options are absorbent glass mat (AGM) and gel batteries. They require less maintenance. These are generally more expensive to buy initially than flooded lead-acid batteries, but what you save in both maintenance time and cost is a consideration for some people.
Lithium batteries are also on the market now, which some are considering for off-grid applications. They are the most expensive to purchase. However, they have more cycles and more amp capacity delivered over the life of the battery.
Battery Bank Setup Basics
When setting up your battery bank there are several things to think about. One of them is the input voltage. This is generally defined by the input voltage of the inverter, which changes the DC current into AC current.
Usually, that will be 12, 24, or 48 volts with higher voltage, generally meaning that less amperage input is required.
The easy way to look at this is that if you only require power for things such as general lighting, small electrical appliances, and any appliances that don't generate heat, 12-volt is usually sufficient for off grid electricity storage.
If you're planning to run heat-generating appliances, electric stove, pumps, microwave, iron, hairdryer, etc. a 24-volt system is a better setup. If you're running any commercial equipment such as electric planers, welders, sawmills, etc. a 48-volt system might be the better way to go.
Having said all this, your average household can generally operate quite comfortably on a 24-volt setup. Any occasional heavier equipment can get powered directly from a generator.
Batteries come in many configurations, usually in sets of 2, 4, 6, 8, and 12 volts. The key point here is that regardless of the grouping, batteries run in series. Each group must equal either 12, 24, or 48 volts while using the same voltage battery.
Examples of Battery Bank Configurations
For simplicity I will include some examples knowing each number represents volts:
2+2+2+2+2+2=12 or 2+2+2+2+2+2+2+2+2+2+2+2=24 and so on
6+6=12 or 6+6+6+6=24 and so on
12=12 or 12+12=24 or 12+12+12+12=48
Now the above groupings are called “batteries running in series” to give you either 12, 24, or 48 volt systems. You can easily increase your system's amperage (storage) by running similar series (groups) of batteries in parallel.
This means, for example, a 24-volt system may be made up of 4 groups of 2 (12 volts) which will leave you with a 24-volt system yet 4x the power stored.
Therefore the more groupings, the more available storage space, yet obviously the greater the cost. This is why it’s good to have a rough idea of your energy requirements.
Batteries For Living Off The Grid: Our Battery Bank System
Now, there are many formulas to use to help you calculate your battery bank requirements. They’re efficient and factual.
For the purpose of this article though, they give too much information and take too much time to calculate. So here’s a real-world example of how we live.
We have a two-story house and run a combination of solar, generator, and propane to power and heat the house.
I’ll break down the exact specifics regarding the generator and propane in a future blog post. Suffice it to say, we’re running a 24-volt system.
We were originally set up as a 12-volt system. This was based on a dozen 6-volt batteries each paired together so we had 6 groups of 2 batteries.
This worked well for our general lighting but was more challenging when operating appliances, pumps, and small tools.
We decided to change the configuration to a 24-volt service that only required changing the configuration to 3 groups of 4 batteries. Each group totaled 24 volts (4x6) and we have three series of 24 volts running parallel which triples the amps for a 24-volt system.
We did this more for convenience since our water system includes running a lake pump for water that requires 24 volts and cannot operate on a 12-volt system. Previously when running the pump, we had to also run the generator at the same time and switch the system to directly run from the generator.
I am always thinking about upgrading our batteries. Yet as previously stated, such things are contingent on available finances!
Update:
On Christmas Eve, 2019, our 40-year-old generator shed burned to the ground. That was the end of our Lombardini generators. We now (finally) have a new 11.5 kW Kubota diesel generator and Tesla 2 Powerwall/Solar panels setup.
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Doug
I have a cabin powered by a 7000 watt Honda gas generator. I want to add a battery bank to my system so I don’t ave to run generator 24/7. The cabin wired and I have a 100 amp service.? How do I tie in a battery bank and charge batteries while generator is running/
Rudy van Acker
I feel that Frank made an error in using 'longitude' rather than 'latitude' in his calculation for tilt, and the angle from horizontal is nominally equal to the latitude of your location.
However. solar panels tilted at an angle equal to the latitude will face exactly midway between the sun’s highest point in the sky in summer and its lowest point in winter. This seems like a reasonable way to maximise solar electricity output, but because days are longer in summer it usually helps to tilt them a few degrees lower to take advantage of this. Seasonal differences in average cloud cover can also alter the optimal angle.
From the pvwatts site https://pvwatts.nrel.gov , for highest total collected annual power, this adjustment is also dependent on the latitude. The angular adjustment appears to vary from +6 at 12deg, -4 at 30deg and -6 at 40deg.
Frank
As a radio amateur I power my radio equipment by lead-acid batteries charged by solar panels ..........although AC power is still available for PC and heating .
For those considering going off-grid using solar panels ,it is very important that solar influx is available for "most of the day" , such that not all solar panels are pointed due south but spread from east to west or somewhere in between . Also the angle of the panels should be right for any specific location on earth , approx 90 degrees minus degrees Longitude (this with horizontal plane as reference)
Frank Amateur Radio EI7KS , KN6WH
Deborah
Sorry to bother you but all these numbers suffice it to say math is not my element. This is my dilemma if you will. I live in the city in an apartment with electricity. When the building lost electricity for 3 days. I realized i need a fallback plan to keep my kitty and i warm. So id need to keep my small bedroom heated, any suggestions welcomed.
Neil Dueck
Very Interesting info. I am total off grid , have 10 6Volt batteries hooked up for 12 volt system , have 8 135 watt solar panels / charge contolers .2800 magnum inverter what benift would I have going to a 24volt system
andrew
great information and thank you, i just bought a new house and have alot of plans for a lot of yard project, one is a screened patio away from your home. it will have an outside kitchen attached but that will run off of wood. i would to run some light maybe a fan and a projector so when my childrens friends come over they can stay there and watch movies. thinking solar to power it, would it better to run 12v or 24v. i am new at all this and want to learn more. thank you and be safe
Sarita Harbour
Hi Carolyn!
Are you thinking of having an alternative energy backup system for a "worst-case scenario?" In the simplest terms, a battery bank is just the place where energy gets stored. That energy either comes from an alternative energy source such as a windmill, or in our case, solar panels. It can also store energy from a generator, which is what we do when we don't get enough sunlight. Hope that helps.
Carolyn
How do battery operated power banks work? I am just one of those people who prepare for the worstand hope for the best.
Sarita Harbour
Hi Carol! Thank you for your thoughtful and encouraging comment. We're so glad you're finding value in our posts. We consider ourselves fledgling off gridders and are continuously learning as we go!
Carol L
Most people who want this type of information want to go "off grid" for reasons other than to be 'independent' of corporations. By that, I mean, we are trying to be prepared for when (not if) WHEN the power goes out AGAIN. In such a case, it wouldn't be at all practical to have your storage elsewhere, if that storage cannot be accessed because the power grid is down due to snow/ice storms or due to over extension of power use, or due to some form of EMP (which, granted will cause any power source to be damaged unless you are prepared specifically for them). I'd like to be free from my power company, just to be more able to live like I want without their interference, ("Smart Meters", etc.) but also because I go without power several times every winter...and am the last one to get power restored. I have options for food, water, heat and light, but it would be really nice to not have to camp out in my home and have REAL heat and be able to have entertainment via dvd's or books read by real light.
I truly appreciate that you write these posts that those like me can learn by your experiences and not have to suffer through the learning process!!!
Thank you!
Sarita Harbour
Good day Michael and thank you for your question.
Since this has potentially many answers, I would request a bit more information:
1) It seems you are currently tied to the grid so do they "buy" back extra energy you create or store it?
2) Do you want to be separate from the grid or maintain a presence with them?
3) Are you considering a balance of solar panels and batteries while also considering the above 2 questions?
4) What are the average hours of sunlight where you are and does it fluctuate seasonally?
5) Do you have many outages currently that you are trying to avoid?
The above are important to know because it is not always economical to be off grid although we believe it is better environmentally. It also depends on the cost per kilowatt that your service provider charges. Batteries are generally the expensive component (stores your generated power) and that is why it is good to know information from #1 above. If they store it, you can minimize, or even eliminate, a battery bank.
Michael
Hi, thank you for your info on "power bank 101" for off-grid living.
I live in a tropical climate, and use an air conditioning unit most of the time (either a window type A/C or split type A/C). This is additional to the water pump, ref, computers, TVs, and electric fans, kitchen appliances.. (my monthly consumption is 1000 kWh)
I would like to try to go off-grid, but I'm not sure if it would be more economical long term? I was wondering if you can give an opinion on this? (I know that this is going to be an expensive setup, but, let's assume that I can afford it)
My main concern is the practicality of being able to live off-grid without really compromising on the small luxuries of city living.
Thank you,
Michael