How Does Solar Battery Storage Work

Our Head of Engineering shares some expert tips on how to calculate your solar battery storage requirements as a high dependency business.

Expert Guide: How Solar Batteries Work

High energy dependent businesses in South Africa need to invest in power security to combat blackouts and brownouts. Our Head of Engineering, Kobus Crauwcamp, shares advice on how to correctly size your solar battery back-up in order to keep your business running efficiently when you need it most.

How to calculate your battery storage requirements

A solar battery solution is not a one-size-fits-all setup. You need to calculate your battery backup requirements based on your unique business environment. This guide will help you to not only size your system correctly but also provide safety considerations when selecting a battery solution.


A PPA is a contract to sell the power a solar service provider (electricity generator) produces to the customer (off-taker). The solar service provider will own, install, and maintain the solar energy system on the customer’s property.

The solar service provider will be responsible for all the costs of purchasing, installing, and maintaining the entire system. The customer will only pay for the electricity they use from the solar energy system at a predetermined tariff.

Sizing your solar battery storage system

It’s important to consider what equipment you need to be able to operate when running off your solar battery. Powering your lights and wifi for example would require a significantly smaller system than powering high power dependent machinery. If there is any heating or cooling required, you may also need to factor gas into your green energy solution. 

How your battery backup system works

There are two components when sizing your solar battery system: an inverter and the battery blocks.

The inverter determines how many KWh can be connected to the batteries including how much of the load can be supplied at any point in time. The batteries determine the capacity of energy stored. If, for example, your system was set up to run your lights and wifi for 6 hours and you accidentally boiled your kettle, you would overload your inverter which could use your entire 6-hour battery storage in as little as 30 seconds.

If your demand is very high, you may need to add additional inverter capacity as well as additional battery banks accordingly.

For example, a 5kW/30kWh backup system can supply 5kW continuously for 6 hours.

What to consider when sizing your solar battery system

There are a few things to keep in mind to ensure you install a solar battery system that’s fit for purpose:

  • How much revenue do you lose when power is out? For example, some businesses are losing around R6 000 per minute in downtime in the steel manufacturing industry; as a nation, South Africa loses billions daily due to planned load shedding.

  • Do your operations use sensitive equipment that needs a constant energy supply and may get damaged if there is a sudden shutdown?

  • Can downtime lead to substantive supply issues? For example, meat suppliers have a window period to process meat safely; without cold storage, it becomes a health risk.

  • Can downtime lead to financial losses from regulatory or legal penalties? For example, your contracts may have fines and fees that you have to pay to the client if you delay delivery.

  • Can loss of power lead to wastage? For example, paint manufacturers are forced to watch their drums sit still during load shedding while the paint hardens; once that happens, the paint is unusable and becomes a loss.

  • Do you need to practise peak shaving to make savings by drawing from cheaper energy sources? Part of your operation, such as machine startup or critical processes, may require a spike in energy use. If you can’t time that spike due to unreliable electricity supply, you may have the energy spike during peak or expensive energy rate periods.

  • Which operations are critical and need constant power? Different industries have very different requirements; for example, in the hospitality industry, you may only want your critical loads on the battery, such as lights, TV, wifi, and restaurant but remove the laundry and pool pump because these aren’t necessary for short periods.

You can book a time with one of our solar experts to help guide you through the process of sizing your solar battery system for success.

Which solar battery is best?

Selecting the best solar battery is important. There are four types of solar batteries available and each of these come with pros and cons.

Types of solar batteries

  1. Lead-acid
  2. Flow battery system
  3. Nickel-based
  4. Lithium-ion

At SolarAfrica we use lithium-ion batteries as our first choice to avoid acid leaks. They are safer than lead-acid batteries and have a superior storage capacity. They are sensitive to high temperatures, but when properly installed and maintained they are the preferred choice by most solar providers. They can also be cycled many times and can handle deep discharge rates.

Lead-acid batteries are usually the most affordable option, however, these batteries come with a few safety risks. Regular maintenance is required in order to prevent lead-acid batteries from leaking. Leaks can cause significant health and safety damage due to the gases released as they charge. They are highly flammable and can cause injuries when they are not handled correctly. When these batteries reach end of life, recycling them is also very complicated and can only be done by certified recyclers.

The sulphuric acid in lead-acid batteries can also destroy your clothing and burn your skin in the process.

Safety tips when working with solar batteries

All solar batteries should be handled with care for your safety. Keep the following in mind:

  1. Educate your team about the dangers of incorrectly handling the batteries
  2. Closely monitor the temperature of your solar batteries 
  3. Make sure that safety gear is worn when handling the batteries (e.g. heavy duty safety gloves and eye protection)
  4. If you have lead-acid batteries and a leak occurs, immediately deep clean the affected area and seek medical care if there is any skin contact

How long will my solar battery last?

All batteries, including your solar batteries, start to degrade over time. A solar battery with a 10-year warranty will last around 6 000 cycles over the 10-year period (at which point the battery will have around 80% of its life left).

How do solar battery cycles work?

Solar battery cycles are calculated in pairs. The first cycle is to charge the battery and the second cycle is to discharge the battery. You would most likely use around four cycles per day.

Each cycle consists of approximately 6 hours and, as the battery degrades, this time reduces. So, for example, you could be getting only 4 hours per cycle.

Why businesses need solar batteries for business continuity

Investing in solar for your business can help you achieve three primary goals — cost savings, power security, and compliance with carbon emission regulations. However, if you want to go off-grid, then solar on its own is not the solution. Solar battery storage is necessary to help keep your operations running smoothly when you’re experiencing power outages and bad weather conditions.

Read our article, The importance of a solar battery system for a high energy dependent business, to learn more about how solar and battery storage can help you achieve power security in challenging times.

When it comes to battery storage, one of the many benefits of partnering with SolarAfrica is their Capex-free lease agreement solution, take advantage of:

  1. No Capex investment
  2. Avoid manufacturing downtime and loss of revenue with immediate, reliable energy for your business
  3. Leverage peak shaving to reduce operational costs
  4. Demand reduction to balance variable loads and reduce unnecessary peaks
  5. Time of use arbitrage to charge your batteries during off-peak times where your tariff is cheaper
  6. Avoid future price escalations with a fixed price for renewable energy

Contact us if you’d like to speak to an expert for advice on the right solution to help your business enjoy all the benefits when investing in renewable energy. 

Planning your organisation’s green energy road map is easier than it seems. Fill in our green energy goals questionnaire to identify the right alternative energy solution for your business.


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Man wearing a hard hat who is working on solar panels