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Heading straight to the point. Solar battery storage bank is a well-defined series and parallel connections of solar battery which are stored up for later consumption. The stored electricity is consumed after sundown, during energy demand peaks, or during a power outage.

So the question is, Do you want to buy solar batteries for your solar storage bank? Then you have to know that there are certain specifications you should use when evaluating your solar battery options. These options are very important to consider because dialing in on the right solar battery bank will make your solar power system a success.

solar storage bank
A WELL CONNECTED SOLAR BATTERY

Thus, you have to consider: the battery’s capacity & power ratings, depth of discharge (DoD), round-trip efficiency, and warranty. So let’s dive into how this criteria affect the success of your solar battery bank.

The battery’s capacity:

The battery capacity is the major and first criteria to consider while choosing your solar battery bank. It is the total amount of electricity that a solar battery can store at a time.

This means that when you have a solar battery with high capacity, your appliances will run for a longer hour. Don’t forget that battery capacity is measured in kilowatt-hours (kWh).

Battery power rating:

Here, the contextual meaning of power rating is the average amount of current which the battery releases over a period of time under normal use. In other words, i can say its the amount of electricity that a battery can deliver at a time.

This means that a battery with a rating of 200 Ah can deliver 20 amps of power at a constant rate for 10 hours.

The connection between capacity and power rating in solar storage bank is very simple. When you have a battery with high capacity and a low power rating, then a low amount of electricity will be produced which is enough to run a few crucial appliances for a long time.

But when you have a battery with low capacity and a high power-rating, big amount of electricity will be produced to run your entire home, but only for a few hours.

Depth of discharge (DoD):

The depth of discharge is always in contrast to the state of charge (SoC). So in a clear definition, depth of discharge shows the ratio or percentage of the battery that has been discharged relative to the overall capacity of the battery when fully charged. To make your solar storage bank last long, you need to understand this clearly.

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To understand DoB in practical sense, lets take a quick example. When you buy a solar battery which holds 13.5 kilowatt-hours (kWh) of electricity, and you discharge 13 kWh, then the DoD is approximately 96 percent.

depth of discharge of solar battery

So when purchasing a solar battery, make sure the DoB is 100%. DoB is expressed in percentage. so get yourself a high DoB battery today and enjoy solar power.

The life-cycle or number of charge or discharge cycle of your solar battery depends greatly on the battery’s capacity you normally use. Thats to say, if you regularly discharge the batteries at a lower percentage rate.

It will have more useful cycles than when you frequently drain the battery to its maximum DoD. Please always have this in mind so as to maximize the lifespan of your solar battery. And also to make your solar storage bank worthwhile.

Round-Trip Efficiency:

Most home solar batteries are designed to be “stackable,” which means that you can include multiple batteries with your solar storage system to get extra capacity. So round-trip efficiency is the useful energy we get back after storing it.

I know that this isnt a common word we are use to,but look at it this way.

round-trip efficiency of solar battery

If you store (5kWh) of electricity into your battery bank and can only get (4kWh) of useful electricity back. Then the battery has 80 percent round-trip efficiency (4 kWh / 5 kWh = 80%). Note that the higher the round-trip efficiency, the less energy you loss due to storage, and the more efficiency of the system as a whole.

Battery Warranty:

It is a common truth that age affects productivity. so solar batteries are no exception. Their performance decrease with age. This means that The battery’s ability to hold a charge will gradually decrease the more you use it.

Thus, the warranty of a solar battery is the number of cycles and/or years of useful life. Some solar batteries in the markets today have a warranty of 25-year long warranty (also known as a performance guarantee).

In most cases, this means a guaranteed electrical production for 10 years at 90% of rated power output and 25 years at 80% rated power output. So now you know the factors to consider while choosing your solar storage bank battery. Let’s take a good look at how long your solar battery should last.

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But before then, how many solar batteries do you need to power your home?

How many solar batteries are needed to power a house?

The question of how much solar battery that can power a home is very common. So I will split it into two sections for clearer understanding. Firstly we need to determine how long a solar battery can power your home. What this means is that you need to do an exact calculation to determine the amount of energy you consume per day.

So after getting the value of the energy consumed per day. The next thing is the capacity and power rating of your solar battery and whether or not you are connected to the electric grid.

Reports from U.S National Energy Information Administration, an average U.S household consumes about 30 kilowatt-hours (kWh) of energy per day. Thus, going by this data an average U.S household needs about three solar batteries because each solar battery produces 10 kWh of capacity.

solar battery bank connection
TIGHT CONNECTION OF SOLAR BATTERY

So you can power your entire house throughout the night without support from an electric grid with three batteries. That’s right! choose solar power today and enjoy constant free power supply.

The second part of this question is based on practical methods. In science, there is always a little drift between theory and practical. Going straight to the point, most batteries cannot run at maximum capacity and generally peak at a 90% DoD (as explained above).

As a result, your 10 kWh battery is likely to have a useful capacity of 9 kWh.

This implies that in a practical sense, you might be needing up to 4 solar batteries in order to power your house comfortably.

How long do solar batteries last?

To determine how long a solar battery should last depends greatly on all the above-mentioned factors. For more clarification, I will focus on the lifespan of a solar battery.
Speaking of the lifespan of solar battery, you need to understand properly the maintenance process of a battery. Without proper maintanance, your solar battery might practically not last up to 3 years.

comparing with the normal useful life of a solar battery which is within the range of 5 to 15 years. But your solar panel can last up to 25 to 30 years, thus there will be a need for replacement as time runs out.

Going back to maintenance, temperature is a major problem which affects solar battery significantly. Thus protecting your battery from freezing or sweltering temperatures can boost its useful life.

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When a solar battery temperature drops below 30° F, it will require more voltage to reach maximum charge; when that same battery rises above the 90° F threshold, it will become overheated and require a reduction in charge.

To solve this problem, many leading battery manufacturers, provide temperature moderation as a feature. However, if your solar battery does not have any moderation feature. Then you will need to consider other solutions like earth-sheltered enclosures.

What are the best batteries for solar storage bank?

Before choosing the best brand for your solar battery bank, there are some factors to consider such as. How much power does my home consume, how long am I going to use it per day? What is the available battery in the market? How much they cost and how long does each of these batteries last. Here is a list of the available batteries in the market:

lead-acid battery:
Lead-acid batteries remain the best solar battery bank that has been used in off-grid energy systems for years. Healthy lead-acid batteries have a short life and lower DoD than other battery types. They are also one of the least expensive options currently on the market and also the best in terms of home energy.

lithium-ion battery:
The majority of new home energy storage bank technologies, such as the use of some form of lithium-ion chemical composition. The energy density of lithium-ion is typically twice that of the standard nickel-cadmium.

They also have a higher DoD and longer lifespan when compared to lead-acid batteries. However, lithium-ion batteries are more expensive than their lead-acid counterparts. lithium-ion battery causes little harm when disposed of.


Salt-water battery: The new salt-water technology makes energy storage safe and sustainable. Very high cycle life at 100% depth of discharge makes this ideal for long-duration solar applications. This non-toxic off-grid solar battery bank that can last a household over 10 years and can handle up to 3,000 full cycles, or 3,000 days and nights. They are also non-flammable, non-hazardous, and non-explosive. Considering this option for your solar storage bank is more than a good idea.

dept of discharge of solar battery
photo credit: ENERGYSAGE

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