Nowadays solar lights are very famous among people. The reason for this is solar lights are very effective in saving energy. Also as solar lights using solar energy to work it helps to protect our environment.
Before going any further it is better to have a quick look at the way solar light works. Solar light has a solar panel that absorbs the solar energy photons/ sunlight and generates the direct current. The generated electricity is then stored in a rechargeable battery. The electricity generation and the storing will happen in the day time. But during when there is no sunlight the solar light uses the stored power in the battery to light up. Solar light has a dark sensor on and off the solar light automatically.
As we know how solar light works let’s get into today’s topic. Can you use regular batteries for solar light?
The safe answer is no you can not. Why we are saying “NO” as a safe answer has a very complex explanation. In this article, we hope to cover all the things you should know.
What is the use of a battery in solar light, how it works?
The battery is a crucial part of a solar light. The reason is solar lights have to work at night when there is no sunlight. So it needs to produce energy during the daytime and stored it to use at night. So we should have a space to store the energy produced by the panels of solar lights during day time. So that is why we need a rechargeable battery.
What happens to the battery fixed in solar light?
When charging the battery continuously, it stores less and less energy after each cycle. So with time, it loses its ability to store energy. So after the life of the battery ends you have to replace it.
What are regular/non-rechargeable batteries?
The non-rechargeable batteries are the batteries that you can not recharge or reuse again after you use it completely. Most people use these batteries because of the self-discharging of the rechargeable batteries.
There are different types of non-rechargeable batteries but the main three types are;
- Zinc carbon batteries
- Alkaline batteries
- Lithium batteries
Difference between rechargeable and non-rechargeable battery?
Both battery types have an anode, cathode, and an electrolyte. Energy will be generated by a chemical reaction happening inside the battery involving these three components. The node is the negative terminal and the cathode is the positive terminal and the electrolyte is the medium that supports the electron flow between the anode and the cathode.
The difference is the chemical reaction is reversible in rechargeable batteries. What happens is during discharge there will be an electron flow from the negative to the positive end. When there is an external energy source connected to the battery’s secondary cell this flow will be reversed and the cell’s charge will be restored. As the chemical reaction is reversible only in the rechargeable battery this can happen only in rechargeable batteries.
Why we cannot use a non-rechargeable battery in solar light?
When we are using solar lights there should be rapid cycles of charging and discharging. But as we know we can not recharge a non-rechargeable battery as the battery will not be fully drained at the night there will be opposing charge flow inside the battery to the direct current flows from the solar panel. Having this kind of blockage daily will damage the battery with time which will result in leakage of hazardous liquids which will cause corrosion.
Also attempting recharging a non-rechargeable battery can cause rupture due to the production of gasses like hydrogen or leakage of hazardous liquids which will cause corrosion of the battery terminals.
Even though some suggest that this corrosion can be cleaned using baking soda and a brush but it will not be possible if the corrosion is very severe. Also when you try to clean this corrosion, water or cleaning liquid can seep into the solar light which will cause damages to the inner circuit. This kind of damages can be permanent. So the manufacturers warn users not to attempt such a thing.
Using an Alkaline battery for two or three days is acceptable if you can not find an ideal rechargeable battery to replace the old battery. But if you use it for more than one week it will certainly damage your solar light.
Do you need special batteries for solar lights?
There are no special batteries manufactured for solar lights. You can use any suitable rechargeable battery available in the market. When selecting a rechargeable battery for your solar light you should consider the following things.
Cycle life – it is better if the battery has a larger cycle life as you can use it for more duration
Size – the battery size should be considered first. Because batteries come from different sizes and different manufacturers may design the battery compartments differently. The most popular sizes are AA and AAA.
Capacity – if you choose a battery with a higher capacity you can store more energy. But your solar light design has to be compatible with that capacity.
Availability – it is better if you can choose a battery that is very easy to find. So you do not have to worry about running out of batteries when you want to replace it.
Voltage – this should be equal to the voltage of the panel of your solar light.
mAh – this depends on the time you want to light up your bulb. More the mAh value more hours you can light up.
Mostly the complete solar light system comes with a battery. So you can readily use it. But you have to replace the battery when the cell cycle life/ battery life span is over. When replacing the battery you can interchange the battery type. But the voltage, mAh, size, and capacity should be equal to the original battery. Sometimes it is okay to choose a battery with a higher mAh value. But if the current comes from the solar panel is not enough to fully charge the battery it might not be useful but it is not harmful.
what are the types of rechargeable batteries in the market?
The most common types of rechargeable batteries in the market are;
- Lead-acid battery
- Nickel cadmium battery (NiCd)
- Nickel metal hydride battery (NiMH)
- Lithium – ion (Li – ion)
- Rechargeable alkaline batteries
The lead-acid battery is mostly applicable for applications where the weight is not much matter. These batteries are not much suitable for solar lights as the weight of the battery is high but can be used if needed. It has a 200 – 3002 of average cell cycle life.
Nickel-cadmium battery (Nicd) – can be used in solar lights. Has prolonged cell cycle life (15002). energy density is less. High discharge rate. NiCd contains toxic metals. So using this battery is not environment friendly.
Nickel metal hydride battery (NiMH) – this battery also can be used for solar lights. This has a higher electron density compared to the NiCd battery. But the cycle of life is less than NiCd (300 – 5002.3). But do not contain any toxic metals.
Lithium-ion – this battery is mostly used in much solar equipment. This is the fastest-growing battery system. Because of the lightweight and also the higher electron density, this battery has become more popular. But when you use this battery you must have a safety circuit. Has a larger cell cycle life (500 – 10003).
Alkaline battery – not recommended for solar lights. Cell cycle life is very much less.
Why do manufacturers discourage using rechargeable alkaline batteries for solar lights?
These rechargeable alkaline cells only have a limited cycle life. The first cycle gives the greatest capacity and the capacity will be decreased from cycle to cycle. If the cycle is deeply discharged then the cell may only provide 20 cycles. So if you use a rechargeable alkaline battery for solar light it will require more battery replacement. Even though alkaline batteries are cheaper than other rechargeable batteries as you need to replace your battery more times it will cost more.
What are the best batteries for solar lights?
The lithium-ion battery is one of the best batteries for solar lights. This battery has high electron density so this means the battery has more capacity. This battery has 3 times of electron density than a standard NiCd battery. Also, this battery has relatively less self-discharged. As the cell voltage is high it makes the battery smaller. Also, the maintenance of this battery is low. Also, the battery life is around 5 – 6 years. These batteries can be easily charged even on cloudy days.
But this battery needs a protection circuit and expensive than the other battery types.
Nicd battery and the NiMH battery both commonly used for solar lights.
NiCd has more cell cycle life. Also, the voltage drop is very less when their charge gets low. So this is an advantage for the equipment.
But most recommend using NiMH even though NiMH has less cycle life than NiMH. This is because NiCd battery contains toxic metals that are not environmentally friendly and NiMH holds more electric charge than the NiCd batteries.