How Many Batteries Do I Need For A Solar House?

Your storage system, consumption, and photovoltaic system all play a role in determining the number of solar batteries needed for your home.

Solar panels and a battery system for the home are becoming increasingly popular as an add-on to people’s self-consumption facilities. In the event of a blackout or when your solar panels aren’t producing enough power, you’ll still be able to use electricity, making it a more and more sensible choice.


how many batteries do i need for a house?

When it comes to the question “how many solar batteries do I need for a house?” there is no simple answer: in this article, we will look at the most important factors that influence the size of a storage system, as well as how many solar batteries you need depending on what you intend to use them for.


The number of solar batteries you need for your home depends on what you want

The answer to the question “how many solar batteries do I need for my house?” is not easy. You may come across many different answers depending on what you want to get out of your solar and storage system.

There are three general ways to optimize a battery system for a home:

  • Design it to save the most money;
  • Design it to have emergency power in case of failure of the external electrical network
  • Design it for self-sufficiency if you don’t have a network connection.

Let’s look at each of them in a little more detail.


Battery system to save money in our house

If you wish to save money on electricity by using solar batteries, you’ll need to know your current electricity rate. In a flat-rate structure, you’ll want sufficient storage capacity to rely as little as possible on the network. The more energy you can store for later use from your solar panels, the greater your long-term savings.

The other primary choice for an electricity rate is a variable rate plan, as with the new power bill; with the day divided into three distinct pricing periods, it is critical to ensure that you have sufficient storage capacity to cover the most expensive parts of the day.

To maximize your savings with solar batteries, you’ll need enough storage to supplement the energy generated by your solar panels and cover your peak-hour use. It is critical to cover the peak hours of 19 to 22h because this is when your solar panels will produce less electricity and will require an additional charge from your batteries.

Importantly, this does not mean you are self-sufficient and do not use the network; it simply means you maximize your solar installation’s efficiency, utilizing as much solar energy as possible. However, if your energy generation is insufficient, you may always connect to the public grid. And if you cover the most expensive hours of the day with solar panels and batteries, the only time you will need electricity from the grid will be at night or dawn, during the cheapest tariff period.


Battery system for emergency power in homes

Solar batteries are increasingly being used as a backup power source in a grid failure. With a solar battery system installed, you can power your home and important electrical appliances in severe weather or grid failure. 

This is achievable if your inverter (which must be compatible with batteriesincludes a backup or emergency exit.

As you can think, the amount of batteries you need to purchase to be prepared for blackouts is highly dependent on your desired level of stability. 

A backup system provides electricity to your house’s important loads for a few hours, whereas a full backup system provides electricity to all of your loads.

A single lithium battery may be enough if your primary concern is maintaining some functionality during brief blackouts (fridge, router, etc.). 

If you’re more concerned with extended outages lasting several hours or a complete backup system that powers all the loads in your home, you’ll require additional storage.


Solar battery system to be self-sufficient in our house (isolated installations from the grid)

Assume you want to install a solar system but do not have access to the grid or do not wish to be connected to the grid. In that case, you will want substantially more solar batteries than any prior applications. And this is because you will be entirely reliant on your photovoltaic system for power.

The critical aspects to consider when determining the number of solar batteries required for a grid-connected photovoltaic installation are the loads you want to power and how long you’ll need to keep those charges on.

As a result, self-sufficiency (isolated photovoltaics) requires a significant storage capacity, much more so if you intend to gather energy for extended periods without sunlight (cloudy weather, nights, etc.). 

To determine the number of lithium batteries you may require based on the consumption you wish to power.


So how many solar batteries would I need depending on the function I want them to fulfill?

Based on high-voltage lithium batteries, manufacturers are now betting on approximately 10 kilowatt-hours (kWh) capacity. Based on this size, a very rough estimate that will change according to your energy requirements is as follows:

  • If you want to save as much money as possible, you’ll need enough battery storage to cover your consumption when your solar panels aren’t producing, either during peak hours or at night: between 1 and 2 batteries.
  • If you want to continue to have power when the public grid goes down, usually with 1 lithium battery of the standard capacities of the market, you will have enough.
  • But suppose you want to disconnect completely from the network through an isolated installation. In that case, you will need much more storage capacity. In this case, it will be very important to make the correct sizing of the installation with an experienced professional.


What factors influence the size of the solar battery system for a home?

Whatever you want out of a solar storage system, some universal factors influence how many batteries you need to install. These criteria include the electricity loads you need to power, your consumption habits, and your solar panel installation’s size/production capacity.

Electricity loads

Anything that consumes energy is referred to as a “charge.” Electricity charges in the case of household solar batteries are appliances and systems such as refrigerators and other appliances and electrical equipment that you can use in your home. As a result, while constructing a storage system, it is critical to understand how much electricity you will need to give to your appliances; depending on the amount of energy required, you will require more or less storage capacity.


Your electricity consumption habits at home 

You must know how much energy you will consume and when and how many hours you will consume energy. On the one hand, this will calculate the quantity of energy you will require at any given moment, which will give you both the kWh you will require and the power, indicating the number and type of electrical appliances you can connect at the same time.

 However, depending on when your peak consumption occurs, you may require more or less storage capacity. Assume you have a time slot rate, and you need to supplement your solar panels with solar energy from your batteries during peak hours. We supplement the energy you require when your solar panels are not producing it at night. More batteries will be required in such a situation than if you merely need to cover the night hours.

Solar panel installation’s size and power output 

Disconnect the battery from the power grid so that you can charge it with the sun’s power instead. Whether you want to save money or make your home safer, solar energy is the best way to charge a battery. Since solar energy comes from the sun, it is important to know how much energy your solar panels make and how much they charge your solar batteries during the day.

You may require more storage capacity than your panels can provide; if so, and considering the possibility of compensating for excess photovoltaic energy, it may be worthwhile to oversize the installation, introducing more solar panels to maximize the benefit from your solar energy storage configuration.


How to calculate how many solar batteries do you need at home?

It doesn’t matter what you want your solar battery to do. The process of figuring out how many solar batteries you need is the same. If you want to use as much energy as possible, you need more storage space than for a simple backup system and for an isolated installation since you won’t have a backup power source. There are different ways to use your solar batteries, so you have to be more or less careful with the calculations. 

So, I suggest that you hire a professional to do the sizing of the installation you need. This way, you can be sure that the calculations are as close to reality as possible. You can get advice on the equipment and the compatibility between inverters and batteries, among other things. However, to help you figure out how many solar batteries you need, here are some general rules.


Calculate the amount of energy you want to cover in your home with your solar batteries. 

To figure out how many solar batteries you need, you need to figure out how much electricity you use when your solar panels don’t make enough. You’ll also need to know: 

  • People who have solar panels don’t use enough electricity during the hours when they don’t work (either at night or at peak times if you have a variable rate)
  • Everything you want to run during those hours will use up a lot of electricity.

From there, you can calculate the number of batteries you need. Multiplying the electricity demand of the appliances and electrical systems you want to work by the number of hours you will need them. I meaning:

Number of equipment x Number of hours x Hourly consumption (Wh) = Total consumption

In the following table, I summarize an example of the calculations of the consumption of the photovoltaic production of a residential photovoltaic installation:

Standard consumption Number Hours Hourly consumption TOTAL CONSUMPTION
LED lighting 4 4 8 Wh 128 Wh
Mobile Charging 2 1 40 Wh 80 Wh
Fridge 1 16 50 Wh 800 Wh
Washing machine 1 0,5 1000 Wh 500 Wh
Microwave 1 0,2 600 Wh 120 Wh
Oven 1 1 2000 Wh 2000 Wh
Hob 1 1,5 2000 Wh 3000 Wh
Hair Dryer 1 0,2 500 Wh 100 Wh
Mini chain/stereo 1 2 150 Wh 300 Wh
PC 1 2 100 Wh 200 Wh
Television 1 2 100 Wh 200 Wh
TOTAL CONSUMPTION       9,918.00 Wh

About 10 kWh of storage space would be needed to cover the electricity that solar panels can’t. Only then would you be able to choose the lithium battery that best fits your needs.