How To Select Battery For Solar Panel?

To get the most out of your solar panels, choose solar batteries with the proper voltage, amp hours, and power rating. If your solar panels output 24 volts of power, you’ll need a battery system with at least 60-65 amp hours to get the most out of them in terms of energy storage.

How can I figure out what size solar battery I’ll require?

The next step is to determine the size of our battery bank! We’ll utilize the same scenario as previously, with a daily energy demand of 1.9 kWh in the winter. To calculate the total energy required for battery storage, multiply the number of days (of energy storage) by one minus the battery SOC we are ready to accept (bearing in mind that typical sizing calls for three days and a 50 percent SOC):

Daily energy use (kWh) x Number of days of autonomy / (1 SOC) = Battery bank size (kWh).

This figure, 11.4 kWh, is the entire quantity of energy that our battery bank must store when completely charged. Working using Amp-hours, a somewhat fictive quantity of Amps we can get out of the batteries for one hour before they are empty, is more convenient for batteries. The number of amp-hours (Ah) is proportional to the voltage of the battery bank. We’ll use a 24 volt battery bank in this example:

When single batteries are connected in series (positive to negative, etc. ), the Voltage of the battery bank is increased while the Amp-hours remain constant. Similarly, when two batteries are connected in parallel, the voltage remains constant while the amp-hours double. We may make this battery bank out of four Surrette S-550 batteries, each with a capacity of 6 Volt 428Ah. When you connect them in series, you have a total battery bank of 24 Volt 428 Ah, which is close enough for our needs!

In our example above, the complete off-grid system consisted of 5 solar panels rated at 295 watts each and 4 Surrette S-550 batteries. That’s pretty similar to our 4-panel cottage kit!

Which solar panel battery is the best?

Solar energy systems typically consist of solar batteries and panels, mounting equipment, and a performance monitoring system. The panels gather the sun’s energy, which is processed and sent to an inverter, from which you can use electricity in your house, business, or industrial setting. Because most homes are connected to the grid, these systems are more commonly used for backup among homeowners. Many others, on the other hand, are looking for a way to replace their utility supply. One of the most popular reasons individuals switch to solar is to avoid high energy expenses.

Solar batteries come in a variety of shapes and sizes, and they’re utilized as a backup for crucial loads when the grid goes down. You can choose from a variety of solar batteries to employ for your system, whether you want an instantaneous backup power system like a UPS or a high-powered one. The solar batteries powered by these panels are designed to provide grid augmentation.

What is a Solar Battery?

A solar battery simply stores the energy generated by your energy system’s solar panels. They may feature an integrated energy conversion and performance monitor in their inverter.

In addition, the storage capacity of various types of solar batteries is proportional to their capacity. Rather than returning solar energy to your grid, the solar battery stores it for later use. The technology will transmit electricity back to the grid after your battery is fully charged. When the battery’s charge is low due to use, the battery will resume charging and draw power from the panels again.

Although batteries are usually attached to house solar energy systems in order to function, they are not required to be helpful for homeowners. In the case of small-scale solar energy storage, electricity from the grid can also be used to charge the batteries. The solar battery is the part of your solar panel system that stores the energy that the panels provide to your home. When the solar panel isn’t producing any electricity, this battery will release the energy it has saved for you to utilize.

If you stay totally off the grid, these batteries can supply homes with 100 percent self-sufficiency as long as the solar panels adequately charge the batteries.

A solar battery bank can properly compensate for power disruptions in businesses or residences where they could spell tragedy. This is especially true in locations where the grid supply is unreliable or when extreme weather conditions necessitate backup power. Solar battery banks are becoming increasingly popular as a source of power at periods when utility bills are at their highest. You can use this developing yet sturdy technology in your house or business, depending on your purpose and desired outcome.

Can Solar Panels Charge Lithium Batteries?

Yes. Lithium batteries, on the other hand, may be harmed by regular charging due to their charge response, among other factors. Bulk, acceptance, and float are the three steps of charging for most solar batteries. Lithium batteries, on the other hand, require two phases of charging.

The first stage is comparable to the bulk stage of other batteries, in which the battery is charged at a constant voltage until it is nearly full. The charging amperage, on the other hand, will be allowed to drain when the device is in the second and final stages of charging. Store charging can also damage lithium batteries by increasing discharge and putting the battery’s life at risk.

Lead Acid

Lead-acid batteries have been used as a stable energy source for off-grid areas for several years. They are usually deep-cycle and low-cost. Lead-acid batteries are known for their high power and discharge current, but they are also known for their low energy. It can take up to 14 hours to fully charge them.

Due to their highly hazardous nature, these batteries must be properly disposed of or they may represent a threat to the environment.

Floating and valve-regulated lead-acid (VRLA) batteries are two types of lead-acid batteries that are often used for solar panels.

The flooded lead battery is a dependable option, but it needs to be watered and ventilated to work properly. The VRLA is available in two types: gel and absorbed glass mat, both of which have valves for off-gassing management (AGM). These are appropriate for both cold and mild temperatures. Although the VRLA batteries provide enough installation flexibility, their temperature sensitivity may be a problem for consumers looking for a long-term alternative to their grid supply.


Lithium-ion batteries are becoming increasingly common for solar systems all around the world. The utilization of this sort of battery in the electric car sector has a lot to do with its development. Its prismatic shape allows for ventilation and makes it ideal for solar applications.

Lithium-ion batteries have a distinct voltage range and charging response (two stages as opposed to the conventional three). A voltage regulator charge controller can be used to charge them. Long-term charging does not benefit lithium-ion batteries, despite their low self-discharge.

This type of solar battery is low-maintenance, has a high specific energy, and has a long lifespan. Lithium batteries are frequently more expensive than lead-acid batteries. They can also need a protective circuit to keep the current and voltage in check.

Lithium-ion batteries, on average, may provide more cycles than lead-acid batteries, making them ideal for providing grid auxiliary services. The high charge and discharge efficiencies of lithium-ion make it a desirable choice for a solar system because it saves energy. These batteries also lose less capacity when they are not in use, which is advantageous in solar setups where energy is only utilized on occasion.

Other alternatives

Nickel-cadmium batteries are known for their low maintenance and ability to withstand a wide variety of temperatures. They are available in a variety of sizes and performance levels, as well as having a lengthy shelf life. However, because of its fast discharge rate and low energy density, this type of solar battery is a poor choice for long-term off-grid power. It also necessitates specific disposal, similar to lead-acid batteries, due to the environmental risk posed by its toxicity.

The sodium nickel chloride battery, also known as the ZEBRA cell, has a high recyclability and produces no emissions. It doesn’t need to be ventilated or maintained. Its high energy density makes it an excellent grid supply backup choice.

Comparing Solar Batteries

When it comes to deciding which solar battery to utilize, you’ll need to take into account a few unique aspects to make a more informed decision. Some things to think about are:


The capacity of a solar battery simply refers to its ability to store electrical energy. Due to their heavier weight, lithium batteries have a higher capacity than all other types of lead-acid batteries. To power a 5.1kW, you’ll need roughly 8 lead-acid batteries, however two lithium-ion solar batteries will suffice. Because lithium batteries have a higher energy density, they can be deployed in difficult-to-reach locations because they can pack more capacity into less space. If you’re installing these solar batteries yourself, you can run into some difficulties due to lithium’s hefty weight. Both nickel-cadmium and sodium nickel chloride have a wide variety of capacities.

Depth of Discharge (DoD)

The DoD of a solar battery is the portion of its capacity that may be used, and a DoD of at least 40% is suggested for maximum battery performance. Lead batteries typically have a DoD of 50%, whereas nickel-cadmium batteries have a DoD of 15%. A battery’s lifespan will be shortened if it reaches this point before being recharged. Solar batteries made of lithium-ion and sodium nickel chloride, on the other hand, have an 80 percent DoD, implying a higher useable capacity.

Solar Battery Life & Warranty

Battery life is the best indicator of a solar battery’s ability to maintain capacity when determining which one to use in your system. A charge cycle is essentially the process of charging a battery once it has been discharged, and it is the most important metric for determining the battery’s lifespan. In addition, the number of cycles your solar battery will go through is determined by how much you utilize it. Even for the same type of solar battery, this characteristic varies and is influenced by the battery’s depth of drain. A guarantee on any brand or product, even solar batteries, is always a good sign of dependability.

Round-trip Efficiency

The difference between the available energy and the amount of energy consumed to charge a solar battery is the round-trip efficiency. The higher the round-trip efficiency of a battery, much like with the DoD, the better. When it comes to efficiency (95 percent), lithium-ion solar batteries dominate since they have the highest conversion rate of solar energy to electrical energy. This means that, depending on the layout of your system, you may need to install fewer solar panels and batteries.

Another factor to consider when choosing a solar battery is the charge rate, which determines how quickly it will be recharged when attached to a charger. It’s a capacity function that’s stated in fractions like C/4. With a charge rate of C/5, lead-acid solar batteries can take up to twice as long to charge as lithium-ion solar batteries, especially during the bulk phase.

You can plan and install your solar system accurately if you keep these considerations in mind. You can choose which type of solar battery is appropriate for you based on what you want to use the system for (backup or main supply).

For a full-time, off-grid supply of varying levels of use, flooded lead-acid and lithium-ion batteries are excellent. The sealed lead-acid kind is your best pick if you’re searching for a battery to utilize in your vacation home or somewhere you won’t be spending much time during the year. It has a low self-discharge rate and requires no maintenance.

You must evaluate the frequency of power outages on your grid supply when selecting a battery for backup purposes alone to predict how many times it will be needed during the year. If it will only be used a few times, a low-maintenance battery, such as a sealed lead-acid solar battery, will be more beneficial. The lithium-ion type is suitable for powering industrial sites where intensive use is expected on a regular basis.

End of Life Solutions

Environmental regulations will be an issue for enterprise and utility-scale solar systems, not just in terms of the types of solar batteries utilized, but also in terms of panel decommissioning, racking recycling, and inverter disposal. Solar battery recycling that goes straight to the refinery ensures that disposal is handled ethically.

What is the best way to connect a solar panel to a battery?

There is a simple formula for determining what big panel you need for your battery, however it is dependent on how many hours of sunlight you get every day (approximately), which in most situations is around six. Battery amp hours multiplied by voltage and then divided by daylight hours is a simple formula.

How can I figure out how big a battery should be?

The formula B = P t / Vdc can be used to calculate the battery size for inverters, where B is the battery capacity in ampere-hour, P is the inverter’s power rating, t is the length of power supply in hours, and Vdc is the inverter’s DC voltage.

What is the life expectancy of a 5kw battery?

We can only execute a single phase installation for those batteries because the Tesla Powerwall 2 has a single phase inverter.

A Tesla Powerwall 2, on the other hand, can be put on a three-phase property. However, it will only provide power to the phase to which it is attached, so you’ll need to inquire more. On three phase locations, the Powerwall 2 can still provide partial backup to specified circuits.

Do I have to switch the battery on if a blackout happens?

Let’s pretend it’s a hot day, and the air conditioners are blasting throughout the home. The electricity goes off. If the battery is unable to bear the load, it will automatically shut off. Then you’ll need to turn off the air conditioners and turn on the batteries again.

If you’re not using a lot of power, the battery will automatically turn on when the power goes out. While the house is powered, the battery is still charging from the solar panels in the background. (Keep in mind that this will only work if your home is powered by a single phase electrical system.)

If the battery is fully charged, how long will it last?

It all depends on what you’re doing with it. The battery will last approximately 12-13 hours if you have a few lights on and are watching TV or cooking. However, if you add a large power user, such as air conditioning or a dishwasher, the battery would be depleted considerably more quickly. After that, it can last for two to three hours.

If you have single phase power and a blackout occurs, you can theoretically back up your entire house – as long as you don’t consume more than 5 kW of continuous power.

Can I feed power from the home battery into the grid and get the feed-in tariff?

Let’s pretend it’s 7 a.m. in the summer and your solar panels are already producing energy. If you have a smart meter, it will check in every 15 minutes or every half hour, depending on how it is configured. If it detects a surplus of solar power, it uses it to recharge the battery.

Let’s say your battery is fully charged by 3 p.m. From that point until sundown, you’ll either be using or exporting the energy you’ve generated.

You should check with your power distributor to see if there is a limit on how much you can export.

How many components do you need for a battery?

You only need the Tesla Powerwall 2 battery if you already have solar panels and an inverter. The battery does come with a gateway box, but that’s just the battery’s energy management system, not the brains.

Soon, you’ll be able to tell the battery what you want it to perform using an app. So you may tell it to stop charging from the sun and start charging from the grid instead. If you don’t generate much solar power or have a time-of-use electricity tariff, where grid power is cheaper at certain hours, this will help.

Should the battery be outside or inside?

It should be kept in a protected location, such as a garage or a shed. We also prefer it to be close to the electrical panel.

We understand that all of this jargon might be perplexing at times, but once you grasp how it works, it becomes pretty straightforward. We’ll try to explain everything in the section below.

Volt or Voltage (V):

The quantity of energy delivered to an electronic circuit is measured in volts. An electronic gadget, for example, is referred to as a circuit. A 12V item is always “given” 12 volts from the battery. A battery’s voltage is always fixed (e.g., 12, 24, or 36 volts), while a device’s voltage is always constant. A device that runs on 12 volts, for example, requires a battery that also runs on 12 volts.

Current Ampere (A):

When we speak of amperes (or amps), we’re referring to the amount of electricity that “flows” each second. When the number of amps increases, the amount of current flowing through the device each second increases as well. The quantity of amps drawn by an electrical equipment is normally fixed, however it might fluctuate depending on factors such as the position of your trolling engine (a trolling engine at full throttle draws more amps than in half throttle for instance).

Example 1: Let’s say I have a Minn Kota Endura C2 50 LBS that is set to gear / speed 2. The trolling motor runs on 12V and draws 15A at the moment. I choose gear / speed setting 4 since I want to travel a little quicker. The engine is still powered by 12V, but it now consumes 25A. Although the voltage has remained constant, the number of amps has increased.

Power Watts (W): :

W = V x A = W = V x A = W = V x A = W = V x A = W = V x A = W = V x A = W = V x A = W = This is the quantity of energy spent by a device, and thus a measurement of its power. This increases as the number of amps increases.

Example 2: Assume I have a 30 amp, 24V Minn Kota Terrova 80 LBS bow motor. As a result, the total power consumption is 720W (24 x 30).

Example 3: Let’s pretend I have another Minn Kota Endura C2 50 LBS in gear / speed setting 2. The engine uses 12V and 15A, resulting in a power usage of 180W. (12 x 15). When I change to gear / speed setting 4, the engine draws 25 amps and continues to run on 12 volts. The trolling motor currently consumes 300 watts of power.

Capacity Amp hours (Ah):

The capacity of a battery is measured in Ah, or Amp-hours. This indicates how many amps the battery can deliver in an hour, as the name implies. A 12V lithium battery with a capacity of 100Ah, for example, can give 100A to a 12-volt device for an hour. The same 100Ah battery could power a 25 amp device for 4 hours (100/25=4). When a battery is labeled 12V50, it signifies it operates at 12 Volts and has a 50Ah capacity. A 24V100 battery has a capacity of 100 Ah and operates at 24 volts. In actuality, the nominal capacity (how many Amps hours the battery can give according to specifications) and the effective capacity of lead-acid batteries are vastly different (how many Amps the battery can actually deliver during use). In our article about discharge and battery capacity, we describe how this works.

Example 4: At 12V, I operate my Minn Kota Endura C2 50 LBS in gear with speed setting 2. I have a 70 ah 12 volt battery. My overall run time is now 70 minutes divided by 15 minutes, which equals 4.7 hours. The engine draws 25A when I move to gear / speed setting 4. My overall playtime is now 70 minutes divided by 25 minutes, or 2.8 hours.

Capacity Watt-hour (Wh):

The capacity of a battery can also be measured in Watt-hours (Wh). The amount of Amps is multiplied by the battery voltage to get Wh. A 12V100 battery, for example, has a capacity of 12 x 100 = 1200Wh (a 12 volt battery with a capacity of 100Ah). The capacity of a 24V50Ah battery is 24 x 50 = 1200Wh. So these batteries have the same capacity; the difference is that one operates at 12 volts and the other at 24 volts. In practice, you’ll find that these batteries have similar dimensions and weight.

Example 5: I have a 600-watt trolling motor and a 1200-watt-hour battery. With this battery, I can run for 2 hours at full throttle (1200 / 600 = 2). To calculate this, I don’t even need to know how the trolling engine or battery voltage function (as long as they work at the same voltage obviously).

The astute reader notices that a device’s battery runtime can be calculated in two ways. Divide the number of Amps in the battery by the power draw in A of the trolling motor, or the number of Wh in the battery by the number of W of the trolling motor.