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With solar capacity getting larger and larger, you will see heavier loads being set on PV modules and batteries. If you want to load 10,000 watts for instance, how many batteries would you need? What capacity is required?
The battery size depends on how long you need to draw the load, the longer the time, the bigger the battery. A 10kwh / 900ah-1000ah battery is the minimum required if you have to draw 10000W for 1 hour, but for 15 minutes a 2.5kwh / 220ah battery will be enough.
How to Calculate 10000W Battery Requirements
The longer you need to run a 10000W load, the greater the battery capacity will be required. It is not so much the number of batteries required, but the size. You can run a 10000W load on any battery as long as there is enough capacity.
To do the calculations, we have to convert watts into amp hours, as that is how battery capacity is measured.
Watts / Volts = amp hours
In this example we are looking for a 12V battery that can handle a 10000W load.
10000 / 12 = 833
So you need an 833ah battery to run a 10000W load for 1 hour. Because of the way batteries work, capacity goes down when you charge heavy loads, so better get an 850ah or 900ah as a cushion. We recommend 3 or 4 Losigy 300ah LiFePO4 lithium batteries for the best results.
Another way to express the formula is kwh x runtime. 10000W = 10kwh, so 10kwh x 1 hour = 1kwh battery, 10kwh x 2 hours = 2kwh battery and so on. When you have the kwh, convert it to watts and divide it by the volts to get the required amps.
10kwh x 1 hr = 10kwh
10kwh = 10000W
10000W / 12V = 833ah
This formula gives you the same results, but we used kwh in case that is the size you are working with. Whichever formula you use, what matters is getting a slightly bigger battery than what the final figure suggests.
Solar power is not perfect and there will be times when production slows down. This applies to solar panels, inverters, charge controllers, generators and batteries. By adding that extra capacity you’ll be able to store more energy and not worry about pushing the battery to its limits.
How Long Can a Battery Last on 10000W?
It depends on how long you need to run 10000W. While the formula above works, we have to remember that lead acid batteries cannot be fully discharged, and second, there is a limit to how fast a battery can discharge.
Batteries have a rating system called C that determines how quickly it can safely discharge. In other words, the rating tells you how many amps a battery can hold. A battery with a 1C rating discharges from 100%-0% in an hour. A 2C battery goes from 100%-0% in 30 minutes, etc.
If you require 10000W for 6 minutes, a 1kwh 10C rated battery will work. For 15 minutes a 2.5kwh 4C battery is sufficient. Again you just need to divide watts by the battery voltage to find the amp hours. The rating also depends on the discharge time. In the example above picked 4C because the discharge is 15 minutes.
Can You Connect Several Batteries For More Capacity?
You can connect batteries in parallel or series for more power. If you get 2.5kwh batteries you can settle for a 2C rating for each as it will be sufficient. Why? Because the batteries only have to discharge at half capacity. You can use either series or parallel configurations, it is up to you. But you must know the volts and how much amps is being pulled to determine how many will be needed.
What Number of Batteries are Needed For 10000W?
10000W, or 10kwh is a lot of power. It is enough to run a refrigerator, air conditioner and other high powered solar appliances at the same time. The average RV uses 20kwh a day so this system can handle 50% of the daily requirements.
The next question is how many individual batteries, solar panels or generators you need. Well it is the same as with the batteries, in that it depends on the capacity of each. If you have an 850-900ah battery that is all you will need. If you have a 450ah battery, you need 2 and so on.
The same rule applies with solar panels. If you’re going to install 350W solar panels, you’ll need 28 to reach 10000W. If you install 300W solar panels, you have to get 34. It is similar to solar generators, the more power, the fewer you will need. And it doesn’t make a difference whether it is one or several. As long as the total is at least 10000W, you can use that power.
How Many Batteries are Needed by a 10000W Inverter?
You need at least a 12V 900-1000ah battery bank to run a 10000W inverter at full power for 30-45 minutes. Why not 1 hour like in our previous calculation? That is because inverters are never 100% efficient, around 90-95%. You have to account for that when calculating how much battery capacity is needed.
If you want to run that load for an hour, get an 1800ah-2000ah battery bank. This will completely discharge the battery, so do this only if it is lithium. For AGM, gel and FLA, 50% is the recharge level. So instead of a 900ah-1000ah and 1800ah-2000, you need 2000ah and 4000ah battery banks respectively.
500W is about 416ah plus another 50 watts for overhead. So 900ah or so is enough. But that is the bare minimum and it is never a good idea to push battery banks because they could overheat. Even if you have a charge controller for protectionLNK, it is better to do your par in preserving the battery.
Slowing the discharge rate will preserve the battery, while a faster charge rate will reduce its life cycle. With a 1000ah battery bank the most you can go is 30 minutes at 10000W. But if you reduce the discharge to 5000W, the battery will run longer.
Another way to look at it is that you need 950ah-1000ah an hour. Unless you have a 1000ah battery, you will need two 500ah or three 450ah batteries in a bank.
If your inverter has a different voltage other than 12V, say 36V or 48V, you can still use 12V batteries as long as the total is equal to the inverter voltage. If you have a 48V inverter, four 12V batteries will do (12 x 4 = 48). A loaded 48V inverter with four 12V batteries can pull 208ah an hour. No matter what the inverter voltage is, the battery bank must provider 10000W an hour.
What Factors Affect the Battery Output For a 10000W inverter?
There are several factors that determine the performance of a battery bank. The following are just some of them and you should consider each thoroughly. Running 10000W on batteries is no joke, so plan first.
- Battery type. not all batteries are made equal, even if they are of the same capacity. A 450ah lithium battery is superior to a 450ah lead acid battery because you can discharge it fully. Lithium ion is lower maintenance and offers superior performance. AGM is better than flooded lead acid but not as good as lithium. The type of battery you choose makes a difference.
- Discharge rate. because lead acid batteries cannot be discharged by more than 50%, you will need extra capacity.
- Inverter efficiency. even if the inverter is the correct size, efficiency is crucial. The difference between an 80% to 85% efficiency can mean several minutes more – or less – running power.
- Duration. we have already covered this so we won’t repeat it. It is enough to say that this is probably the biggest factor that determines how long the battery will last.
- Battery voltage. most batteries have 12V, but 24V, 36V and 48V are available. 24V and higher are superior to 12V, but they are more expensive.
Running a 10000W load on solar power is no longer an unusual sight. With battery capacities becoming larger and more affordable, we should see more of these thousand watt loads, and it is always a good thing to see greater usage of renewable energy.