Solar Battery Backup System Buying Guide

In South Africa, load-shedding is only getting worse, with 2023 being the worst year on record and 2024 not looking any better. So, if you want to be free of Eskom and not have to worry about rolling blackouts, you need a solar battery backup system.

Solar batteries can allow you to be completely independent of your utility system. You can either go off-grid or remain tied to the grid but still benefit from having power during blackouts. 

Let’s examine everything you need to know about solar battery backup to help you buy the right system for your home. 

What Is a Solar Battery Backup System?

Solar batteries are an essential component of any hybrid or off-grid solar system tied to the grid but not dependent on it for electricity. It’s a battery or collection of batteries that store the electricity produced by your solar panels, also called photovoltaics.

They allow you to switch to battery power to keep your lights on and your essential appliances running even when the electrical grid goes down, which, in South Africa with Eskom’s increasingly common load-shedding, can occur almost daily. Without batteries, you’re at the whim of your utility company.

For those who want to go off the grid, batteries are essential to run appliances at night or during bad weather when your photovoltaics can’t produce enough energy to meet your needs.  

You can also use the batteries without photovoltaic panels. However, they wouldn’t really be solar batteries, and you’d still have to rely on Eskom’s power to charge them. They’ll provide you with some backup power during load-shedding, but if your blackout lasts too long, it could leave you without electricity. 

How Do Solar Batteries Work?

Solar batteries are rechargeable batteries that store the electricity produced by photovoltaic panels. The panels capture photons from the sun and convert them into DC (direct current) electricity, which flows into your batteries, charging them and storing the DC electricity so it’s there when you need it.  

From there, your batteries have a balance of system (BOS). The BOS includes an inverter, which converts DC electricity into AC (alternating current) electricity, which your home uses to power your lights and appliances. It also consists of a charge controller and a battery management system to keep everything running smoothly and efficiently. 

It helps protect your battery from overcharging and other issues that could reduce its lifespan. Then, when you need power at night or when the grid goes down, you can use the electricity that you produced with your photovoltaics during the day, stored in your batteries. This allows you to be independent of load-shedding or other unscheduled power outages since you no longer rely on the grid to meet your energy needs. 

Solar Batteries Advantages & Disadvantages

Advantages 

• Solar batteries allow you to store electricity during the day when your photovoltaics produce electricity using energy from the Sun. Then, you can still have power at night when the sun isn’t shining. 
• It reduces or even eliminates your electricity bills if you have enough capacity. 
• They provide complete energy independence and are no longer reliant on the grid, so you’ll still have the power to run your lights and appliances during load-shedding or unplanned blackouts. 
• Their energy is clean and carbon-free, producing zero greenhouse gases or toxic pollutants. 
• Technology has advanced significantly while becoming more and more affordable.
• They’re often eligible for significant tax incentives and rebates.
• Installing photovoltaic panels and batteries could increase your home’s value by 3-8% compared to homes without.

Disadvantages

• Savings and net-metering options vary depending on your utility company.
• It requires an initial investment that not everyone can afford. 
• Older lead-acid and lithium-ion batteries (not including new LiFePO4 models) may pose health and fire risks and don’t last as long as newer models. 
• Lead-acid batteries will require regular maintenance to ensure they last as long as possible (also not needed in newer LiFePO4 models).

Types of Solar Battery Backup Systems

Depending on what you want from your photovoltaic backup system, you can choose between grid-tied and off-grid systems. 

Grid-Tied Solar Power Systems

Grid-tied systems produce electricity using photovoltaics but remain tied to the grid. This can be useful if you only have a few photovoltaic panels and no battery backup. However, grid-tied systems without batteries will leave you at the mercy of your utility company and will not provide power when the grid goes down. 

If you want a grid-tied system but still want energy during a blackout, you can use a hybrid solar system that uses photovoltaic panels and backup batteries, with a balance of system designed to switch to the batteries automatically when the grid goes down. That way, you can have the benefits of photovoltaics and the independence of an off-grid system but still remain tied to the grid, where you can benefit from net metering and keep your electricity bills to a minimum. 

Off-Grid Solar Power Systems

Off-grid photovoltaic systems aren’t connected to the grid. They’re completely self-contained in your household, allowing those in remote locations far from the grid to enjoy the benefits of electricity. They’re also great for those who want complete independence from utility companies like Eskom with their load-shedding rolling blackouts.

Off-grid systems are similar to hybrid systems in that you need photovoltaic panels and a battery backup system, with a balance of systems to convert DC electricity into AC to power your home.  

Types of Solar Panels

Monocrystalline Solar Panels

Monocrystalline solar panels, like EcoFlow’s 400W Rigid Photovoltaics, are made from a single silicon crystal and boast the highest conversion efficiency at 23%. They also last the longest since they are more resilient to thermal degradation and other factors that can reduce their useful lifespan. Because they are more complicated to manufacture, they used to cost more. But thanks to innovation from companies like EcoFlow, they now cost about the same as polycrystalline panels. 

Polycrystalline Solar Panels

Polycrystalline panels are made from multiple smaller silicon crystals melded together to create a photovoltaic cell. They’re cheaper to make and have a lower conversion efficiency of between 13% and 16%. This means you’d need more panels to create the same amount of electricity. Polycrystalline panels are also more prone to thermal damage, so they typically have a shorter lifespan, especially in hot climates.   

Thin-Film Solar Cells

Thin-film cells are made from a thin layer of photovoltaic material deposited onto a glass, plastic, or other surface. They’re helpful when you want flexibility and are typically the cheapest type, but that comes with a price. They have the shortest lifespan and usually the lowest conversion efficiency.

What To Consider Before Buying a Solar Battery Backup System

Before you buy components to set up a solar battery system, there are several factors you should consider to help you find the best option for your home. 

Capacity

The battery capacity, or how much energy you can store, typically recorded in kWh, is critical. How much capacity you need will depend entirely on the size of your home, how many people live there, what appliances you have and how often you use them. You should calculate your energy usage to determine what capacity you’ll need. For whole home backup, you want an expandable system like EcoFlow’s DELTA series to add extra batteries if your energy needs increase. 

Portability 

Portability can be crucial, especially if you like camping or on game drives and want to travel comfortably. EcoFlow’s RIVER 2 series portable power stations are perfect for their lightweight and portability. This means you can pack them for hiking, fishing, or for a day on the beach. For those with higher energy needs, EcoFlow’s DELTA series is more robust yet still portable enough to use in your campervan.  

Battery Chemistry

There are different types of battery chemistries to choose from. Lead-acid models used to be the popular choice due to their lower costs. However, newer LiFePO4 batteries are quickly becoming increasingly affordable, last the longest, and are the safest choice. 

Cycle Life

Different battery types can vary significantly in their cycle life. A battery’s cycle life – also called its charge cycle – is how many times you can recharge it before it starts losing capacity. A deep-cycle lead-acid model may only have 100-200 charge cycles compared to LiFePO4 models, which can often be charged 3000 times before they begin losing capacity. 

This means the initial savings on the lead-acid models are no longer worth it with the declining prices of LiFePO4.   

Monitoring Options

It’s a good idea to purchase batteries with monitoring apps that allow you to receive alerts, monitor your usage, and maximise your efficiency, as opposed to batteries that don’t let you optimise your system performance. Monitoring apps can save you money and help extend the life of your battery.

Safety

Safety is another critical consideration. Older lead-acid batteries frequently discharge toxic gases, and if they tip or experience temperature fluctuations, they’re prone to leaking acid that can corrode anything it spills on. Older lithium-ion models were also prone to thermal runaway, which sometimes caused fires or even explosions. Newer LiFePO4 models aren’t prone to any of those old safety issues, so if safety is a priority for your family, they are your best choice. 

Warranty

Always avoid manufacturers that don’t offer a good warranty or have warranties limited to the number of charge cycles you have used the product for. If the manufacturer doesn’t stand by its product, neither should you.  

Price

Of course, price is a significant factor for most of us. But don’t be fooled by the initial cost savings. Lead-acid batteries are still the cheapest, but they last a much shorter period of time. So, those initial savings will cost you significantly more in the long run, considering you may have to replace them 3-5 or even more before replacing your LiFePO4 battery just once. 

Another price factor to consider is looking up government tax incentives or other solar rebates in your area. You might be surprised at the discounts available to help you get the system you need at a price that works for you.

Frequently Asked Questions

Final Thoughts

Now, you have all the information to help you decide on the best solar battery backup system for your household. Consider whether you want an off-grid or on-grid system, and consider your batteries’ capacity, cycle life, battery chemistry, safety, and warranty options. 

Purchasing one of EcoFlow’s Portable Power Stations is your way to energy independence, so you never have to worry about load-shedding again.