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Estimating How Long Will a Solar Battery Power Your House

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When it comes to powering your home with a solar battery, the key question is: how long will it power your house?

The answer isn’t straightforward because it hinges on how much energy your home uses, the size of the battery, and how efficiently the system operates.

Think of a solar battery like a water tank and your daily electricity use as the amount of water you need.

If you have a big tank (a large battery) and you only use a small amount of water each day (low energy use), then your supply will last longer.

Conversely, with a smaller tank or higher water usage, you’ll need to refill (recharge) more often.

There’s also some water that evaporates (energy loss due to inefficiency), which affects how long the supply lasts.

Essentially, the duration a solar battery can power your home is a balance between these factors, tailored to your unique energy profile and needs.

How Long Can A Solar Battery Power Your House on Average?

How long a solar battery keeps your house running is determined by the size of the battery and how much electricity your home uses.

Typically, a 10 kWh solar battery could last from half a day to a full day.

If you want it to last longer, you could use energy-saving appliances, be smart about when and how you use electricity, take good care of your solar equipment, and make sure you choose the right number of batteries for your needs.

Factors that Determine How Long Will a Solar Battery Power Your House

The length of time a solar battery can power your house depends on several factors:

Solar Battery Capacity

Capacity refers to the energy that your solar battery can store. It is bound to determine how long the battery will hold its power for obvious reasons.

The unit for measuring the storage capacity is kilowatt hours, known as kWh. Battery capacities range between 1 and 10 kWh, which can also exceed that, especially in commercial power systems.

In other instances, people use several batteries simultaneously to boost their capacity. Despite using your solar battery during power outages, avoid discharging it fully.

It is important to remember that for the following reasons;

  • Your solar inverter will need the charge to start recharging the battery using solar power in the morning once the sun comes up
  • It also helps your battery stay healthy

If you own a 10-kWh battery, you only need to spare 0.5 kWh for these purposes. Therefore, you will have up to 9.5 kWh to use.

Energy Consumption of Your House

Another thing that can determine how long your solar battery holds its charge is the appliances you own. The most common ones include the following;

  • Heating and cooling
  • Kitchen and cooking
  • Lights
  • Refrigerator
  • TV and device charging
  • Water heating

Some use up a lot of power; excellent examples are heating and cooling appliances. So, in case of a power outage, limit how long the equipment stays on to ensure your battery lasts for a long time.

What about a look at how much power the various appliances use?

Kitchen Appliances

  • A newer refrigerator version may use between 1 and 2 kWh per day, whereas older counterparts take up to 5 kWh daily.
  • The coffee maker needs 0.12 kWh per brew or 0.4 kWh per hour on warmer
  • The dishwasher (energy saver cycle) needs 0.5 kWh per load
  • The electric oven needs 2.3 kWh per hour
  • Microwave oven needs 0.12 kWh per 5 minutes
  • Oven: surface needs 1 -1.5 kWh per hour
  • The toaster needs 0.04 kWh per use

Water Heating Appliances

  • Electric water heater needs 4-5 kWh per day after running 2-3 hours)
  • Heat pump water heater with a capacity of 50-75 gallons needs approximately 2.5 kWh per day


  • 8 W CFL or LED equivalent to 25 W incandescent needs 0.008 kWh per hour
  • 15 W CFL or LED equivalent to 60 W incandescent needs 0.015 kWh per hour
  • 27 W CFL or LED (27 W), equivalent to 100 W incandescent, needs 0.027 kWh per hour
  • 38 CFL or LED equivalent to 150 W incandescent needs 0.038 kWh per hour

Device Charging

  • A desktop computer needs 0.06 kWh per hour
  • The laptop computer needs 0.02-0.05 kWh per hour
  • Modern TV: LED/OLED 4k or 1080P HDTV (20″ to 70″+) needs 0.014 to 0.18 kWh per hour
  • A tablet needs 0.032 kWh per day
  • TV: Plasma (40″ to 50″+) needs 0.4 to 0.48 kWh per hour
  • WiFi router needs 0.024 kWh per day

Heating and Cooling Appliances

  • The baseboard heater (6-foot unit) needs 1.5 kWh per hour
  • The ceiling fan needs 0.025-0.075 kWh per hour
  • Central AC (3 ton – 12 SEER) needs 3.0 kWh per hour
  • Cooling Window/Wall AC (8k to 18k BTU) needs 0.73 to 1.8 kWh per hour
  • Electric furnace (with fan) needs 10.5 kWh per hour
  • Pedestal fan needs 0.03 kWh per hour
  • A portable heater needs 1.5 kWh per hour

Medical Equipment

  • Nebulizer needs 1 kWh per hour
  • A sleep apnea machine (CPAP) needs 0.2 kWh per hour
  • Oxygen concentrator needs 0.46 kWh per hour

So, you can do some math to identify the power your house needs depending on the appliances at hand.

The Power Your Solar System Will Produce

Since a solar battery is a power backup, it will have to rise to the occasion whenever your solar system fails. Its power determines how long the battery can hold its charge.

The amount of energy is measured using kilowatts (kW) and calculated hourly.

Since solar production fluctuates since it is weather-dependent, this measurement determines when the panels work under ideal conditions such as peak sunlight.


Batteries lose some energy in the form of heat when they charge and discharge. Inverters also have efficiency ratings that affect total usable power.

Depth of Discharge (DoD)

This is the percentage of the battery that has been used compared to its total capacity.

Most solar batteries are not used to their full capacity to extend their lifespan.

Household Energy Prioritization

If you prioritize your energy usage, powering only essentials, a battery will last longer than if you’re powering everything as usual.

As an example, if you have a 10 kWh battery with a DoD of 90%, you effectively have 9 kWh of usable capacity.

If your home uses 30 kWh per day, you’ll need to ration the power or have additional batteries to get through the day, especially if there’s no solar panel input.

Solar Battery Types

The type of solar battery you have does affect how long it can power your home. There are several types of solar batteries, each with different characteristics that influence their performance, including capacity, lifespan, depth of discharge (DoD), and efficiency.

Lead-Acid Batteries: These are the oldest type of rechargeable battery and are more affordable. However, they typically have a shorter lifespan and a lower DoD, which means you may need more of them, or they may not last as long on a single charge compared to other types.

Lithium-Ion Batteries: These are more expensive but have a higher DoD, are more efficient, and have a longer lifespan. They can store more energy and release it more effectively, so they tend to power your home for longer periods compared to lead-acid batteries.

Nickel-Based Batteries: Such as nickel-cadmium or nickel-iron, are less common for residential solar systems and have specific maintenance and performance characteristics that can also affect their operational duration.