Solar System Batteries (Important Facts)

How many solar batteries are needed to power up a house?

A battery bank of 88 batteries, 6 volt can power an American house of 30 KWH consumption for a week. However the number of solar batteries needed to power up a house is totally depends on the load of the house. The more the load in the house, the more will be the number of batteries.

 Also, it depends on the condition of the SUN light. In summer there will be more need for the batteries and in winter there will be less need.

Usage of electricity in homes is measured in unit of kilo watt hours. The electricity bill shows the number of kilo watt hours spent in a month.

 The requirements of the energy of 1 kw-hour is equal to the 100 watt device for 10 hours or one kilo watt device for 1 hour.

 According to the reports of American energy information administration(eia), an average American house uses almost 901 kilo watt hours in a single month or almost 30 kilo watt hours in a single day.

Specifications of a battery is a critical factor in deciding the number of batteries to power up a house.

For example, a 400 amp-hours battery will be able to supply 4 amperes for the 100 hours. Usually the voltage of battery is constant but it decreases slowly when the battery is powered up.

 For estimation of the energy capacity of a battery in the unit of kilo watt hours, operating voltage is multiplied with the amp-hour rating of the battery and then it is divided by 1000.

So, a battery of 400 amp-hour that generates 6 volt voltage can supply almost 2.4 kilo watt hours.

Let’s talk about a week consumption, a battery bank needed for an average American house would need to supply almost 210 kilo watt hours.

 As we discussed in the last paragraph that battery will supply 2.4 kilo watt hours, so almost 88 such batteries are needed to power up a house for a week.

 But in reality more batteries are required to cater the battery imperfections and the power used by the converter.

During hot days, obviously less number of batteries will be required and during cold days, more number of batteries will be required. The load for the hot and cold days can be estimated from the electricity bill of those months.

For mor information about Ampere Hour Meaning, read my detailed article here.

Can I use solar panel without the Battery?

YES, solar panels can be used without battery. However there are advantages of having batteries with the solar panel setup, but it’s not essential.

Batteries are required when SUN is not completely exposed or clouds are there or at night or something like this.

In the Grid-tied systems, batteries are not required. People draw power from the grid in this system when sun is not shinning fully or at night. Grid is actually a giant battery in this case.

If one has the net energy metering facility then even extra energy during full shiny midday can be sent to the grid and can earn the money. 

It is really worthy to have batteries with solar panels as there are areas where there are no grid-tied system or net metering system. You have to have batteries along with the solar panels to power up the house for whole day and night.

Solar panel can be used without the battery. Solar panels can be used for charging the dead battery. Obviously the output of solar panel is not standard amount of energy.

The output varies for the whole day depending on the shine of the sun. From 12 volt to the 48 volt, solar panels have different voltage outputs. Let’s suppose a solar panel has been specifically designed for charging a 12-volt battery.

In this case, panel can be connected to the battery and it will charge the battery without any damage.

But what if solar panel is not designed specifically for charging a 12 volt battery, in this case after connecting the panel to the battery, fluctuating voltages will be there and light intensity will increase and decrease.

More voltage causes the battery to produce the gas and causes it’s electrolyte to bubble and as a result battery will be ruined. A charge controller can be used for regulating the amount of solar energy that is pushed through to the battery.

During power outages, if a battery is connected to the solar panel set up, then supply will not be disconnected even at night or at early in the morning or when sun does not shine well.

But if there is no battery then during power outages supply will be disconnected at night or at early in the morning or when sun does not shine well.

How Can I run my AC on solar without battery?

AC can be run on solar without battery in grid-tied system. As far as Grid-off system, DC powered air conditioner is required along with the wide operating voltage.

It is possible to run AC on solar without battery but it’s not practical. Solar panels are not those sources of energy that give constant energy throughout.

In fact no more than one simultaneous moments will be the same, because of the involvement of many environmental factors.

Batteries are helpful in stabilizing the power. As air conditioners are sensitive electronic equipment, so a constant and clean source of the energy is required for smooth operation. Even a small battery can solve the stabilization problem.

Can I use my car battery for a solar panel?

Yes, a car battery can be used for solar panels but there will be significant changes in the output and efficiency. A car battery is type of a starter battery that is designed to produce short but powerful amount of currents for starting the car engine.

The flow of the electricity is quite significant as compare to the solar battery. As far as lengthier and stabilized supply of energy is concerned, there is no comparison between solar and car battery, solar battery is far better than the car battery.

Solar batteries are designed to store the energy for a longer period of time. These batteries are also different to car batteries as they can provide electricity for the longer hours.

Solar batteries can withstand different charging and discharging cycles without affecting the lifespan of the battery. Durability of the solar batteries is quite good. Car batteries are cheaper but it is the wrong choice for solar panels.

How do you know if a solar panel is charging the battery?

There are three simple steps to follow for checking the charging of the battery.

Firstly, voltage of the solar panel itself is measured.

Secondly, Voltage of that point should be measured where the solar panel is connected to the battery.

Thirdly, the voltage of the battery should be checked but take care wires should be unattached.

If there is any disconnectivity then solar panel is not charging, otherwise it is charging.

Loose battery connection should also be checked. For solution of loose connections, reattach the connections. Corrosion should also be checked, properly clean it.

Charge controller role is pretty much important to know whether solar panel is charging battery or not. When solar panel is producing the power and batteries are in the charging state then charge controller should display the sign of the current flowing from the solar panels towards the batteries.

Battery charge status will be determined when voltage will show on the display screen of charge controller. In case of lead acid battery, charging voltage’s maximum value should be 14.6.

A new or old solar panel charges the battery or not can be checked by the above mentioned method.

If battery is not charged, then culprits can be many. Wrong solar panel setup, Faulty battery, or the issues in the solar charge controller.

If there is the issue with the solar charge controller, reset the controller and then connect the solar panel, battery, and the charge controller in a proper way.

There can be problems with the battery as it can be incompatible with the solar panel. Battery can be broken. Leakage and discoloration should be checked in the battery. Another problem with the battery is sometimes we don’t charge the battery for a long time and it remains idle, this battery will not charge directly again from the solar panel.

Can I replace solar panel battery?

Yes, solar panel batteries can be replaced by a common man but it’s a good approach that you hire a technician for this as there can be some complexities in the process.

The replacement of a battery in a solar system depends on many notable factors. Type of the battery is quite common factor. Different batteries have different life spans like lead acid battery has 4 to 8 years life. Lithium has almost 10 plus year life.

Another responsible factor is the maintenance, means how these batteries are maintained.

Third factor is the environment in which batteries are kept. Check that they should be kept in an environment having appropriate temperature, neither very hot nor very cold.

Smaller size battery can be replaced with larger size depending on the need of the load. Faulty battery can also be replaced with the new one.

Before replacing the battery, it is ensured that all wiring and battery system settings are accurate. Also ensure that system of solar panel is converting DC to AC and then it is transmitted to the battery correctly. After this assessment switch off the power supply.

AC power supply will then be disconnected from the older battery. AC coupling will be used to establish the connection between the solar panel and the battery. The AC power for the new battery will come from the conversion of energy happened in the solar panel cells.

After securing the AC, new solar battery can be placed. Old battery inverter should also be changed as it plays a vital role for the long life of the battery.

For tools we use in electrical work read my article here.

How long do solar batteries last?

It depends on the quality of the battery, it’s rating, and the amount of the load connected to it. For example an average home that draws 750 watt to 1000 watt power in one hour during the power outage.

A battery of 10 kWh will last almost 10 to 12 hours and a battery of 13.5 kWh will last almost 13.5 to 16.8 hours.

Solar batteries usually last almost in between 5 to 15 years, but YES there is no hard and fast rule in it. Lifespan of a solar battery depends on some factors.

Type of the solar battery is one of the major factor as far as lifespan is concerned. Usually there are three types of chemical compositions in batteries. Lithium Ion, Salt water, and the lead acid batteries are these types.

Lead acid batteries is considered as the least expensive option. They have a short lifespan as compare to lithium Ion and have lower depth of discharge as compare to Lithium Ion batteries.

Standard answer for the lifespan of lead acid batteries is 3 to 5 years. The lifespan of Lithium Ion batteries is almost around 5 years.

Unlike lead-acid and lithium Ion, these batteries contain saltwater electrolytes instead of the heavy metals. These are the most environment friendly. Out of all these, lithium Ion batteries offer the most reliable service.

Another important factor in life expectancy of a battery is its usage cycles. Fortunately, most of the batteries are deep cycle batteries allowing them to discharge 80% of the storage energy before the recharging.

Battery temperature is also an important factor as far as life expectancy and efficiency is concerned. It should be kept at an optimal temperature. Proper timely maintenance of the battery is also very critical for the longer life of the battery.

Replacement of the battery totally depends on its condition, so check whether it is functioning properly or not. As far as preventive maintenance is concerned, just stick to the basics like cleaning and keeping the battery at optimal temperature, it will perform well.