If the power goes out, you won’t be able to use your solar system if it is connected to the grid. It automatically turns off to keep you safe, so having batteries is a good idea. The question is how many 200-ah batteries you will need to power all of your devices. How long will it last?

With four 200-ah batteries, you get 9.8 kwh, which is about 9600 W. This is enough power to run a fridge, five light bulbs, a TV, a laptop charger, and a TV for 3.9 hours.

**How many 200ah batteries do I need for my house?**

You should think about two important things. First, you need to decide how many things you want to run and for how long.

From these, you can figure out how many 200-ah batteries you need. As for which brand to buy, we recommend the Renogy 200ah Battery because it is made for off-grid use.

**You can use this simple formula to figure out how many batteries you will need:**

**Total ****W****/KW= size of the battery**

Batteries are measured in amps, so to figure out how many watts they produce:

**W/****V**** = ****A****mps**

Ax**V**** = ****W****atts**

How to Calculate Battery Power for a House

Here, we need to make a few assumptions. First, it’s not possible to run a whole house for days on batteries. You can, however, use batteries to keep your home or cabin’s appliances running for a few hours if the power goes out. In our example, let’s say you only want to run the most important appliances, like:

Appliance |
Power Consumption |

Refrigerator | 2000 WStarting / 780 running |

60W light bulbs (5) | 300 W |

Mobile device charger | 60 W |

45 inch TV | 100 W |

Total: 2460 watts / Battery Required: 4x200ah / Runtime 3.9 hours |

The total is 2,460 watts, or 2.5 kilowatt-hours. These rates of consumption are just a guide. Look at the label on your product to find out how much power it needs.

This is just an example; you may have other ideas about what kinds of things are important appliances. Just add your own devices to the list above and figure out how much power they use.

The total number of watts is now 2460. How many batteries with 200ah do you need? First, we need to figure out how many amps a watt is. If you are going to use a 12V battery:

200ah x 12V = 2400 Watts

You need at least two 200ah batteries to even start your power load. But the question is how many batteries you will need to keep your devices running. This is what the next section is about.

**How Long Will My Batteries Last?**

How many 200ah batteries you need is based on how long your appliances run. Once you know how long it will run, you’ll know exactly how many and what kind of batteries to buy.

**To find out how long the battery will last:**

**Battery capacity / total wattage = appliance runtime**

You need four 200ah batteries to run a 2460-watt critical load for about four hours. 9600 watts is the same as four 200-ah batteries.

200ah x 12 = 2400

2400 x 4 = 9600

Multiply the power of the battery (9600 watts in this case) by the power of the appliance (2460 watts):

9600 / 2460 = 3.9

Going back to the example we used before, your appliances use 2460 Watts, which is 2.5 kwh. One 200ah battery is only 2400 watts, which isn’t enough. You have enough power to keep your appliances running with four 200ah batteries.

If you want your appliances to run for longer periods, just add more batteries or reduce the critical load. If you add more to the load the runtime will drop.

Adding a 2000 watt window AC for instance, brings the total wattage to over 4000 watts.

9600 / 4000 = 2.4

The length of the movie drops from almost four hours to two and a half. To make it last for four hours, you need to add another 200ah battery. With this formula, you can figure out how many batteries you need for a certain amount of time.

We did these calculations with 200ah batteries, but you can try other sizes. But because of its size, 200ah is great for homes. But if you can get a big battery, you can power more things.

**What Batteries Should I Use?**

One thing to remember about these calculations is that it will use up all the power in the batteries. And that’s important, especially if you use deep cycle lead acid.

AGM and gel batteries that use lead acid have a 50% discharge rate. This means you shouldn’t let the battery capacity drop below the halfway point. Why? Because it is bad for the way the battery works on the inside. Lithium batteries, on the other hand, are made to be used all the way down, but they cost more.

So, your 2460 power load will run for about four hours if you use four 200ah lithium batteries. This will run down the batteries, but lithium batteries can handle it.

Since a 50 percent depth discharge is normal for lead batteries, does this mean you need eight of them? Well, that depends on how often you use the system.

If there aren’t many power outages in your area, it’s fine to let lead acid batteries run down completely. If you take good care of your batteries, your power system should work fine. But if you use these batteries in your appliances often, you should either double their capacity or switch to lithium.

**Can I charge my battery bank with solar panels?**

** **Yes, solar panels and batteries can work together. In fact, that’s how most homes that don’t use the grid are set up. As long as your solar array is big enough, your appliances should work just fine. But what number do you need?

It will take nine 300-watt solar panels to power a 2.5-kwh load. This is based on the idea that you’ll load all the appliances at once. If you only want to load a fridge and lights, you only need eight panels. We suggest the ACOPOWER 300W Solar Panel Kit because it is a good deal and works well.

You can save battery power by running your solar panels in the morning and only using them at night. But you can only do this if you are not connected to the grid. In the event of a power outage, grid-tied systems automatically turn off your solar panels to keep you safe.

If you live away from the power grid, you need a battery bank or another way to get power. Add the total wattage plus the reserve power to run a solar panel and battery system (20 percent minimum). And don’t forget the charge controller and inverter.

To be clear, you do not need solar panels to use a battery bank to power appliances. You will need a charge controller and an inverter. You don’t have to use solar panels. But if you have a system that doesn’t use the grid, you probably already have an array set up.

**Tips For Using Battery Backup Power**

Setting up a battery backup system can be hard and expensive for someone who has never done it before. Here are some ways to make sure your money and time are well spent.

**Figure out which appliances you want to keep running if the power goes out. **Most people need a refrigerator, a heater, an air conditioner in the window, lights, a laptop charger, and a TV. You are the only one who can decide what is important for you and your family.

**Check the running and maximum wattage of each device you want to run. **Both will be on the label or in the instructions. Starting watt requirements are needed for refrigerators, air conditioners, heat pumps, washing machines, well pumps, and stoves. Some appliances, like a refrigerator, have on/off cycles, so they will turn on and off over and over again, using more power each time.

**Always have some extra power on hand. **If the total load is 2460 watts, the battery must be much more powerful. In the case of lead acid batteries, you may want to double it. Don’t forget that the size of the battery will also depend on how long you want the appliances to run. These numbers are for running important appliances for a few hours a day. If you need a backup power source for several days, you will need a big generator and other power sources.

**Try out your bank of batteries. **When the power goes out, the last thing you want is for something to not work. Check the wires and cables, since problems usually start there.

**Check to see that your batteries are full. **Batteries don’t like to sit still for long periods of time, so make sure to use them every once in a while.

## Conclusion

In the end, it all comes down to what essential appliances you want to use and for how long. Using 200ah batteries to power your home in an emergency is possible if you only use basic appliances.