How Long Can a Solar Battery Power a House?

Solar Battery

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The idea of using a fully charged solar battery to help offset your electricity costs has become very popular in Australia, especially with the peaks of summer and winter pushing out air conditioners to the max. But how long can a fully charged solar battery last, and is it enough to power a house? 

A fully charged solar battery can power your entire home normally for two to four hours, or up to two days if you only run essential items like fridges and lighting. However, different solar battery models have different capacities, which will affect how long a solar battery can power your home. 

If you’re looking to improve the autonomy and efficiency of your solar system, then look no further. This article will discuss solar batteries and how they can help reduce your electricity bills and your reliance on the grid. 

To find out more, continue reading! 

How Much Energy Does a Solar Battery Store? 

Solar battery capacity is measured in kilowatt-hours (KWh) and ranges from 1.2kWh to 28kWh. The exact capacity will differ between models and among manufacturers. The more money you spend on your solar battery, the more capacity it will have and the more solar energy it can store. 

It is important to make a distinction between kilowatts (the measure of power) and kilowatt-hours (the measure of energy). These two numbers are present in solar batteries and together indicate the effective operating time of a solar battery.

For instance, if a solar battery can store 20 kWh of energy with a power of 5 kilowatts, it can be charged or depleted at a rate of 5 kilowatts (the maximum rate) and will consequently take three hours to be fully charged. The battery’s brand, size and model will all affect much energy the unit can store. 

Remember that solar batteries are not like your small everyday batteries, which you can stack or use multiples of to achieve the power needed. Solar batteries are meant to operate as a complete system. If you eventually require a battery with a much larger capacity, you cannot just purchase another battery of the same model and use them simultaneously. 

In cases like this, you should instead purchase a solar battery with a larger capacity — one that is proportional to the energy needs of your household or establishment. Just remember that the battery size you choose will influence how much a solar battery costs, which is something you need to factor into your budget. 

How Much Solar Power is Needed to Power a Home?

A solar system generating 30kWh of energy should be enough to power most homes, as according to the CSIRO, the average four person home uses between 16 and 18kWh of energy daily. However, the size of your home, solar system and family will all affect how much power is needed to power your home. 

Determining the correct size and capacity of a solar PV system for your home requires knowledge of how much electricity you’re currently using and how much more electricity you might be using in the future (especially important in cases where the family is expecting a new baby, or simply expecting to grow).

There are several ways to determine electricity usage, one of which is to review past electricity bills. You can determine the average monthly, quarterly, or daily usage from the data on the bills. If you have a smart meter installed, checking it should give you a more precise figure. 

Electricity consumption depends on many factors, such as the number of people residing, the area or state you live in, what appliances you use, how often appliances are used, and whether your house is populated or in use.

The specific models and types of appliances will also affect energy usage. A household that uses electric stoves or induction cookers will use more than those who use gas for cooking. Activity in the house should also be considered. Sometimes people are out on the weekends, or the house could be empty during the day if most or all residents go to their offices. This shows that it’s difficult to use hard-and-fast rules to determine energy usage without looking at specifics. 

The factors that will affect future home electricity usage include:

  • Working from home more often
  • Planning to start a family or expand the family
  • Adding a swimming pool 
  • Switching from gas cooking to electric
  • Purchasing an Electric Vehicle (EV)
  • Improving the house’s resale value

These factors are often a sign of higher energy consumption. So make sure to include this when you’re planning to install or expand your home solar PV system, like increasing the number of solar panels you have or adding a battery to your solar system

How Long Can a Fully Charged Solar Battery Power Your House? 

On average, a homeowner will use anywhere from 750 to 1,000 watts of power per hour during an outage or power interruption, up to a maximum of 2 kilowatts. So a 10kWh solar battery will be able to last for roughly 10 to 12 hours. 

Remember that the purpose of solar batteries during outages is to ensure usable electricity throughout the outage and maintain essential appliances like your fridge and lights. Using electricity like normal will significantly reduce the time your solar battery can power your house. 

How Long Will a 10kWh Solar Battery Last? 

A 10kWh solar battery will last anywhere from 10 to 12 hours of use with an average consumption of 750 to 1,000 per hour. This duration lessens as you use more power.

How Long Will a 5kWh Solar Battery Last?

A solar battery with a 5kWh capacity can last up to 10 hours if you only run a few lights and the fridge. You may expect a 5-hour runtime if you use around 1,000 watts per hour.

How Long Will a 3kWh Solar Battery Last? 

A solar battery with 3kWh will not last too long; 3 hours is the limit if you’re using around 1,000 watts of power per hour. You can lengthen the duration by only using the bare essentials and rationing your electricity.

What Size Solar Battery Do You Need to Power Your Home at Night?

An 11kWh solar battery will power the average Australian home at night because the average Australian home uses 30% of its electricity consumption during the day, and 70% during the night, mostly due to people being out at work during the day. 

The issue for most people is the upfront cost of larger batteries, even considering the available solar battery rebates. For instance, the Tesla Powerwall 2, which has a 13.5kWh capacity costs around $15,000, including installation, which is more than many people are willing to spend, even if it will save money in the long run. The silver lining is that there is actually no need to offset the entirety of your night-time power consumption with solar batteries.

If you do some calculations, you will see that the best payback is from the first kilowatt-hour of energy storage because it works the hardest. Subsequent kilowatt-hours have longer paybacks, so you don’t have to spend a fortune trying to account for every single kWh of electricity your house uses at night. 

The critical factor in determining the solar battery needed will still be an in-depth understanding of your household’s energy usage profile. Of course, if the main reason you want a solar battery back-up is to power your home in case of an outage, you may want to opt for a larger capacity!

How Long Does a Solar Battery Hold a Charge? 

Most modern solar batteries can hold a charge for anywhere from one to five days. However, differing types of batteries, models, and capacities will affect how long your solar battery can hold a charge. 

How Long Does a Solar Battery Take to Charge?

For most batteries, it will take anywhere from five to eight hours of charging to go from completely drained to fully charged. The exact charging time will depend on the type of battery, the current capacity and the weather.


This article is published in good faith and for general informational purposes only. JFK Electrical does not make any warranties about the ongoing completeness and reliability of this information. Always seek personalised advice on solar energy to ensure any recommendations suit your property and scenario.

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