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Types of batteries that are best suited for solar power

Types of batteries that are best suited for solar power />

08/07/2020

The use of solar power is becoming increasingly popular in homes. Many find it to be a viable option for lowering their electricity bills and providing backup in times of power cuts. A key component in an off grid solar setup, along with the panels and the charge controller, is the battery. There are different battery options available in the market that can work with solar panels. However, not all of them would yield optimal results.

Today, BPZ would like to discuss the types of batteries best suited for solar power. We would also explore the pricing of these batteries along with their respective advantages and disadvantages. We would conclude our discussion by explaining whether solar lights need a different kind of battery compared to the normal solar setup.

In a broad sense, deep cycle batteries are best suited for energy storage in solar applications. When compared to automotive batteries, deep cycle batteries are not as adversely affected by deep discharge cycles. In addition they need to have quicker recharge capabilities as well as high resilience in PSC (partial state of charge conditions)  where the batteries may not be adequately re-charged on a regular basis which in the case of normal batteries would result in plate sulphation and possible early demise.

Deep cycle batteries are designed to provide a steady current of relatively low magnitude for longer durations. This is a desirable feature for a solar power system where the battery may need to power electronics for an extended time. On the other hand, automotive batteries can be damaged permanently if they are regularly discharged below 50% of their full capacity. Automotive batteries or SLI batteries (starter, lights, ignition), prime purpose is to provide a short burst of current and not extended deep discharges. These properties make automotive batteries unsuitable for a solar power system for any reasonable life expectancy.

In terms of specific battery types, two popular battery choices for solar power systems are lead-acid batteries and lithium-ion batteries. The lead-acid battery is cheaper and, therefore, a good option if one is on a limited budget. These generally come in the form of flat plate AGM (absorbed glass mat) or GEL electrolyte.  Tubular plate batteries are available in wet electrolyte options (which will require periodic maintenance) or Gelled electrolyte which are classified as maintenance free.  Voltage configurations vary from 2 volt, 6 volt and 12 volt. Dependent on the size and technology of the batteries. Lead acid is generally substantially less expensive than its Lithium Ion counterpart.

Lead acid batteries possess lower depth of discharge characteristics. As a direct result regular deep discharges can cause rapid deterioration of lead-acid batteries. On the other hand, lithium-ion batteries are much more expensive than lead-acid batteries, but they offer various benefits as well. They are lighter and more compact when compared to lead-acid batteries. Their lifespan is longer due to their higher depth of discharge (up to 100%). Their rechargeability is phenomenal in terms of time and they may be operated in a partial state of charge without any damage to the battery. Their cycle life capability is at a far higher rate than most lead acid batteries – by up to 10 times in some batteries. As a due result, lithium-ion batteries are used in most modern solar power systems.

We refer to the TOTAL COST of ownership. That is the expectant life that one is expecting budgeting on in terms of the battery. The key input value is the number of times that the battery of choice will need to be replaced relative to the expected lifespan. It is not uncommon, for example: that a lesser quality lead acid battery could be replaced two to three times in a ten-year lifespan than a good quality lead acid AGM or Gel battery. In most instances one good quality lithium ion battery would last the full ten-year period (some are guaranteed for ten years) and could still have 60% of usable capacity left, even after ten years. 

Solar lights are another scenario where solar technology and batteries are used in conjunction with one another. Solar based lightning solutions are being used for both the interior and exterior of homes. Both lead-acid batteries and lithium-ion batteries work well with solar lights.

As solar technology progresses, it is expected that new types of batteries would emerge as well. That is why it is best to stay in touch with the latest trends within the solar battery market. As a result, one can be aware of the available options which will allow one to opt for the best possible choice in one’s solar system of choice.