solar battery

How a Solar Battery Enables Your Eskom Independence

In the quest for a sustainable and resilient power supply, solar has emerged as the primary solution in South Africa. Our abundant sunshine makes solar in South Africa a great option.

However, the true transformation lies not only in solar panels but in the storage and utilisation of solar energy. This is where the solar battery comes into play.

Traditionally, the power landscape in South Africa has been heavily reliant on Eskom, which we know is vulnerable to disruptions and dependent on fossil fuels. The improved technology offered by today’s solar panels and solar batteries, however, is shifting the paradigm and reshaping the way we think about energy generation and consumption.

By storing excess solar energy, solar batteries offer a game-changing solution to the intermittent nature of solar power, unlocking a host of benefits for residential, commercial, and even utility-scale applications.

One of the most significant roles of solar batteries is their ability to power a home or business during an Eskom outage or load-shedding period, regardless if the sun is shining or not.

The role of solar batteries in energy storage

In a renewable energy system, energy storage plays a vital role in overcoming the inherent intermittency of renewable sources like solar power. Energy storage refers to the ability to capture and store excess energy produced during high generation and release it when demand is high, or generation is low. This capability is crucial for creating a reliable and sustainable power supply.

energy consumption vs solar production
energy consumption vs solar production

Energy storage addresses the challenge of matching electricity supply with demand, as renewable sources often generate power inconsistently due to weather conditions or time-dependent factors. By storing surplus energy, renewable systems can bridge the gap between production and consumption, ensuring a steady and uninterrupted power supply.

Solar batteries store the electricity solar panels generate during periods of high solar irradiation. The stored energy can then be used when solar generation is low, such as in the early morning, at night or during cloudy days.

Residential and commercial applications benefit greatly from solar batteries. For residential users, batteries can store surplus solar energy during the day and use it in the evening or during peak demand hours. This reduces dependence on the grid, lowers electricity bills, and provides homeowners with a reliable backup power source during outages.

Additionally, your residential bill is subject to stepped tariffs. By using solar and solar battery stored energy, you effectively reduce the most expensive stepped (block) rates being charged to your electricity bill.

See the example below of a Johannesburg City Power invoice from 2022.

city power stepped tarrifs

2023 included a 7.5% increase in our electricity rates. Below is what we currently pay for electricity from City Power in Johannesburg.

city power rates 2023


In commercial settings, solar batteries have a broader impact. They allow businesses to optimise their energy consumption by storing excess solar energy and using it when electricity demand and costs are highest. This practice, known as peak shaving, helps businesses reduce their reliance on grid power during expensive peak hours, resulting in significant cost savings.

Grid-tied vs off grid battery considerations

To run your home entirely off the grid requires at least 18 hours of battery backup power. The cost associated with this size of battery backup is enormous and will run into hundreds of thousands! Not to mention the space required to house all the batteries. The good news is that you don’t need an off grid size solar battery system.

Due to the very high cost of solar system batteries, we suggest purchasing the required batteries to keep your home or business going for an extended load-shedding period only. This is roughly 4-5 hours during stage 6 load shedding.

In winter, we have only 6 hours of usable sunlight. Therefore, we suggest as many panels as your roof can support; and a solar battery backup that can hold your essential load (no geysers, pool pumps, heaters etc) for at least 4.5 hours. The rest of the time, you utilise the unpredictable Eskom grid supply. In summer, you will enjoy most of your savings, but a solar system spec like this will save significant energy and remove the worry of load shedding from your family or business.

grid tied solar

What is Depth of Discharge, and why is it important?

When evaluating solar batteries, one crucial factor to consider is the depth of discharge (DoD). DoD refers to the percentage of a battery’s total capacity that can be used before it needs to be recharged. It indicates how much energy can be extracted from the battery before it reaches a low state of charge.

Understanding the depth of discharge is essential because it directly affects the battery’s lifespan and performance. Batteries with a higher DoD allow for a larger usable capacity, meaning they can be discharged more deeply before requiring recharging. This increases the amount of energy that can be stored and utilized, maximizing the battery’s efficiency and overall system performance.

Different battery chemistries have varying depth of discharge capabilities. Let’s explore two common battery types:

Lead Acid Batteries

Lead acid batteries are widely used for energy storage applications – you have one in your car – including solar panel systems. These batteries typically offer a DoD of around 50%, meaning they can discharge up to 50% of their total capacity before recharging. While lead acid batteries have a lower DoD than other technologies, they are still suitable for many residential and commercial applications due to their low cost. Unfortunately, our very regular load shedding cycles are too extreme for lead acid batteries – and you can expect a very short lifespan when using these types of batteries in South Africa.

One advantage of lead acid batteries is their affordability, making them a popular choice for budget-conscious consumers. However, it’s important to note that lead acid batteries require regular maintenance, including checking electrolyte levels and ensuring proper ventilation. Additionally, their lifespan and performance can be affected by factors such as temperature fluctuations and depth of discharge cycles.

Lithium Ion Batteries

Lithium-ion batteries have gained significant attention recently due to their higher energy density and superior performance to lead acid batteries. These batteries offer a higher DoD, typically 80% to 90%, allowing for greater utilization of their total capacity.

The higher DoD of lithium-ion batteries means more energy can be stored and utilized, maximizing the efficiency of solar panel systems. Additionally, lithium-ion batteries are known for their longer lifespan, lower self-discharge rates, and faster charging capabilities compared to lead-acid batteries. These features make them an attractive choice for those seeking a high-performance and low-maintenance energy storage solution.

However, it’s important to consider that lithium-ion batteries are much more expensive upfront compared to lead-acid batteries. Care should also be taken to ensure proper battery management and safety measures when working with lithium-ion technology due to their sensitivity to temperature extremes and overcharging.

Understanding the depth of discharge is crucial when selecting a solar battery. Lead acid batteries offer a DoD of around 50%, while lithium-ion batteries provide a higher DoD ranging from 80% to 90%. The choice between these battery types depends on factors such as budget, performance requirements, and maintenance considerations. Consulting with a reputable solar power installer can help you determine the most suitable battery technology for your specific needs.

Benefits of energy storage with solar batteries

Energy storage with solar batteries offers several benefits that contribute to the transformation of the power landscape:

  1. Grid Stabilisation: Solar batteries enhance grid stability by smoothing out the variability of solar power generation. They store excess energy when generation is high and release it during periods of high demand or when solar generation is low. This helps reduce strain on the grid and provides a more consistent and reliable power supply.
  2. Peak Shaving: Solar batteries enable peak shaving, a practice that involves drawing stored energy during times of high electricity demand. By utilising stored energy instead of relying solely on the grid, peak shaving reduces the need for additional power generation capacity and helps alleviate stress on the grid during peak periods. This not only benefits individual consumers but also supports overall grid stability.
  3. Load Shifting: Solar batteries allow for load shifting, which involves storing excess solar energy generated during low-demand periods and using it during high-demand periods. Load shifting helps balance the load on the grid by shifting energy consumption to times when electricity demand is lower. It maximises the utilisation of solar energy and reduces reliance on fossil fuel-based power plants during peak hours.

Studies demonstrate the impact

Numerous case studies illustrate the transformative impact of solar batteries in achieving grid independence. For instance, in regions prone to frequent power outages or with limited grid infrastructure, solar batteries have provided a reliable and continuous power supply. Remote communities and rural areas have benefited from off-grid solar systems, where solar panels coupled with batteries have enabled access to electricity and improved the quality of life.

In developed areas, solar batteries have demonstrated their capability to reduce dependence on the grid during peak demand periods where electricity can cost far more. Commercial buildings and industrial facilities have effectively implemented hybrid systems, utilising stored solar energy during expensive peak hours and significantly reducing electricity costs. These examples showcase the potential of solar batteries in enhancing grid independence, empowering users to have greater control over their energy consumption and reducing their reliance on the traditional power grid.

Maximising Self-Consumption and Cost Savings

Maximising self-consumption is a crucial aspect of optimising energy use and unlocking the full potential of solar power systems. Self-consumption refers to the utilisation of the energy generated by solar panels on-site, rather than exporting it to the grid. By consuming more of the solar energy they produce, individuals and businesses can save on electricity costs and reduce their reliance on grid power.

Self-consumption with solar batteries offers significant financial benefits, both for residential and commercial users.

Firstly, self-consumption reduces the electricity purchased from the grid, resulting in lower energy costs. Rather than buying electricity at grid rates during peak hours, users can rely on stored solar energy, which is typically cheaper or even free once the initial investment in solar panels and batteries is recovered. This leads to long-term savings on electricity bills, allowing users to allocate their financial resources to other priorities.

Secondly, self-consumption helps mitigate the impact of increasing electricity prices. As utility rates continue to rise, relying on self-generated solar energy becomes increasingly advantageous. Users are less susceptible to fluctuating energy prices, making budgeting and financial planning more predictable and stable.

In addition to direct cost savings, self-consumption contributes to the overall financial viability of solar power systems. By maximising self-generated solar energy, the return on investment for solar panel installations and battery systems is accelerated. The reduced reliance on the grid and potential revenue from exporting excess energy can further offset the initial costs of the system, making solar power a financially attractive and sustainable option.

Environmental Impact and Sustainability

Solar batteries play a vital role in reducing carbon emissions and combating climate change. By storing excess solar energy, these batteries enable the utilisation of clean and renewable energy even when the sun is not shining. This reduces the reliance on fossil fuel-based power generation, which is a significant source of greenhouse gas emissions.

Integrating solar batteries into the energy system allows for more efficient and sustainable use of renewable energy. It enables a shift towards a low-carbon economy by reducing the need for traditional energy sources contributing to climate change. By maximising the utilisation of solar energy and minimising dependence on fossil fuels, solar batteries help to mitigate carbon emissions and make significant strides towards a more sustainable future.


Solar batteries are revolutionising the energy sector, promoting grid independence, maximising self-consumption, and reducing carbon emissions. They offer financial benefits, environmental sustainability, and energy resilience. By embracing solar batteries, we can create a future powered by clean and renewable energy, ensuring a sustainable and resilient power landscape for generations to come. Let us seize this transformative technology and work together towards a brighter and greener future.