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How Long Can Solar Batteries Hold Charge?


The role of a solar battery is to offer backup power, mainly if the solar can’t produce energy or there is a grid outage. Since the period that such issues can last is often unpredictable, it would be great to have a reliable family.

Various things determine how reliable it is. For example, how long can solar batteries hold a charge?

Since it isn’t forever, knowing the precise answer to such a question is advisable for great planning. So, without further ado, let’s answer this million-dollar question.

How Long Does a Solar Battery Hold its Charge?

Solar batteries are similar to other batteries to a great extent. Therefore, it is unnecessary to recharge them now and then.

After fully charging your solar battery, it may not need recharging for a few days. Depending on your battery, it could be a day or even up to 5 days.

Some batteries, especially Tesla batteries, can hold their charges even longer. To be exact, a Tesla battery can hold its charge for around 7 days.

Do Solar Batteries Go Bad If Not Used?

Having established that a solar battery can hold its charge, can it go bad if you don’t use it for a while? On the contrary, the stored charge significantly ensures that the solar battery doesn’t go bad despite not being used for long.

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Otherwise, storing a fully discharged solar battery without use for long will damage it within no time. That battery will lose its ability to hold its charge, thus becoming useless.

Fortunately, such an eventuality is avoidable; all you can do is use trickle chargers. They ensure that your solar battery is always charged, thus avoiding complete depletion.

However, keeping your solar battery charged is just one way to take care of it. Adhering to these instructions and recommendations will help your solar battery last more than a year despite being unused for a long time.

How Long Will a Solar Battery Power Your House?

Whereas solar batteries store their charges, it is also clear that the period is different among them. That’s because of various factors affecting this period.

Let’s look at these things which make the difference.

The 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
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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.

The Power Your House Will Need

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
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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.

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