Solar Battery Guide

Solar Batteries: A Beginners Guide

In this article, you are going to learn all about Solar Batteries.

You will understand what the differences are between the types of solar battery, how they fit into a Solar System, how many you’ll need and more.

Here’s the breakdown:

Let’s get started.

Chapter 1

What Are Solar Batteries

Lets start at the beginning

In short, Solar Batteries store power, either solar power produced from your solar panels or grid-supplied power so that you have electricity supply when it is nighttime or when the grid fails.

However, solar batteries do not work on their own. They need other equipment to manage the charge and discharge rate, manage the overall health of your battery bank and convert DC stored power to AC power which we need to run our appliances.

You will typically use a solar battery in one of two instances, namely a Solar Power Kit or a Load Shedding Kit.

Battery Storage Options - A Beginners Guide

Load Shedding Kit

Load Shedding Kit Icon
A Load Shedding Kit contains a Solar Inverter, a Battery Bank and peripherals like disconnect switches and wiring. There are no panels with a Load Shedding Kit. However, you can add panels later if you want to.

Solar Batteries store DC (Direct Current) power, but we use AC (Alternating Current) in our homes.

The inverter will convert the grid-supplied AC power to DC power when your battery is charging. And when using the power stored in your battery, the inverter will convert the DC power to usable AC power.

Solar Power Kit

Solar Power Kit Icon
As the name suggests, a Solar Power Kit contains a Solar Inverter, Battery Bank, Peripherals and Solar Panels.

Solar Power Kits supplement your usage with freely produced solar power during the day and supply power during load shedding because you have a battery bank.

More often than not, your Solar Panels will charge your battery bank during the day so that you can use the stored solar power in the evenings and during grid failure.

Solar Power Kits will save you money on electricity where Load Shedding Kits will not.

Chapter 2

Fundamentals

Solar lingo explained

Understanding the terms used in this guide is very important as they’ll help you understand what to look out for when sizing your own battery bank. If you know the basics, skip to Chapter 3.

Deep-Cycle

What does Deep-Cycle mean?

You will hear the term “Deep-Cycle”, what this refers to is the  Depth Of Discharge . Deep-Cycle Solar Batteries are  specifically designed to regularly discharge until it has used most of its capacity .
The depth of discharge will depend on the type of battery you choose.

DOD

DOD

DOD (Depth of Discharge) refers to how much of the battery can be used.
A typical  Lead-Acid Battery will have a DOD of 50%  . Whereas with the  Lithium-ion Solar Batteries have a DOD of between 80-100% , this is important to understand when calculating your solar battery needs.

Chapter 3

What Kinds Are Best For Solar Power?

In short, there are 2 main types of Solar Batteries, Lead Acid and Lithium-ion

AGM Lead Acid

Sealed Lead Acid

An upgrade to the flooded version, Sealed Lead Acid eliminates the maintenance required compared to its counter partner.

It’s not without its drawbacks, however, a very short lifespan compared to that of the Lithium-ion Battery and they end up being more expensive in the long run due to the fact that they will need to be replaced in about 3 years time.

How do Lead Acid Batteries work?

AGM (Absorbent Glass Mat) are capable of handling higher temperatures with a lower self-discharge when they are idle. The cells have a lower resistance compared to conventional cells, they don’t leak and they don’t need to be in an upright position.

New AGM batteries cannot be connected in series to existing, older batteries as this will damage the newest addition.

Pros

  •  Completely sealed so no risk of acid leaks 
  •  No maintenance is required 
  • Don’t have to be mounted upright
  • Charge quicker with a lower voltage
  • Lower initial cost

Cons

  •  Lifespan from around 3-5 years  (depending on brand)
  • Need to replace more frequently
  • Only  50% depth of discharge  is recommended

Lithium-ion

The most efficient battery on the market Lithium-ion battery technology is the future of solar storage. They waste significantly less power when charging and discharging. The cycle is deeper using more of their capacity with a long lifespan.

Completely maintenance-free they are lighter, smaller and they don’t produce as much heat as Lead Acid batteries and are perfect for setups that have space restrictions.

Easy, versatile Installation

Lithium-ion batteries come in a number of sizes and are easily installed. Should you need to add new batteries later, you’d simply need to add them to your existing battery pack.

Furthermore, you are able to choose how and where you’d like to install them. Lithium-ion batteries are available in wall-mounted, floor-mounted and rack-mounted options which give you the freedom of choice. For rack-mounted batteries, you also have the choice of a cabinet.

Lithium-Ion Batteries | What you need to know!
Pros

  •  Maintenance free 
  • Lighter and smaller
  • Don’t have to be mounted upright
  •  Produce more cycles (6000 – 10000) 
  • Can produce 100% of the stored energy
  • Lifespan from around 10-20 years
  • High charging and discharging efficiency,  more than 95% 
Cons

  •  Highest cost 
Chapter 4

How to Size a Battery Bank

In 3 easy steps

To begin, it’s a good idea to check the power ratings of your appliances. You have to make sure you have a large enough battery to accommodate your needs.

Let’s Start

Now to work out what size solar battery bank you’ll need, you’ll need to work out what you want to run off your battery and for how long you need to run these appliances.

There are three main questions you need to answer:

  1. What appliances need to run off the battery bank?
  2. For how long do these appliances need to run off the battery bank?
  3. Will your battery be used during load shedding, evenings, nights and mornings?

Whatever your answer is, you’ll be able to work out your kWh needs by following the steps in this section.

I’ll refer to load shedding, evenings, nights and mornings as ‘downtime(s)’ as this is the period you’ll not be producing solar power.

Step 1

Step 01
Add the power ratings of all the appliances you’d like to run off your solar battery bank.
As I have said, it is a good idea to  check each of your appliances for their ratings  to get an exact idea of your usage.

Step 2

Step 02
Next, we’ll need to  work out the amount of time you typically use these appliances .

You’ll use your appliances for varying amounts of time throughout the down phases. Like a TV might be on for 4 hours while your microwave is only on for 3 minutes.

This section is entirely reliant on your usage.

Step 3

Step 03
 How will you use your solar battery ? Load shedding? Non-production time? Both?

Non-Production Time Guidelines

Below are some guidelines for figuring out how many hours you’d like to run your appliances off your battery bank.

Load Shedding Usage

Loadshedding
In some areas, they can expect  2.5 hours of load shedding , and in other areas, they can have up to 4 hours of load shedding. It’s essential to consider these times.

Evening Usage

Evening Usage
The average evening usage is around 4 hours for appliances that we use when we’re awake from when we come home from work till the time we go to bed. We’ll work from 18:00 to 22:00.

Nighttime Usage

Night Time Usage
Say you’re getting in a good night sleep at the recommended 8 hours a night. Most of us still run a few essential appliances like fridges, alarms etc.

Morning Usage

Morning Usage
We use a lot of power in the mornings because we use appliances like kettles, toasters, microwaves and hairdryers. All of these appliances pull large amounts of power.

Usually, between 06:00 and 10:00, we don’t produce enough solar power to supplement our load. Therefore, it is beneficial to have a big enough battery to cover as much of our usage in the morning as possible.

As a rule of thumb, we suggest being mindful of what you are running off your battery bank, but mornings are different because who wants to start their day de-caffeinated with a severe case of bedhead?

In the next section, we’ll take a look at a case study of my home to show you exactly how to work out your battery needs.
Chapter 5

Adding Up All The Data

Now we get to the fun part: working out our usage!

Below, I’ll give you an example based on my home and the appliances we own with their ratings, how many times we use them, and how long we use them in 16 hours.

I have broken them down into three sections.

  • Mornings
  • Evenings
  • Nights

Mornings

Appliance Watts Number of uses Duration of usage Total Watts
Espresso Machine 1450W 2 10 minutes 484W
Toaster 850W 1 3 minutes 43W
Microwave 1200W 1 minute 20W
Hairdryer 1000W 1 10 minutes 166W
LED Lights x 10 @ 5W each 50W 1 3 hours 150W
TV x 2 @ 160W each 320W 1 2 hours 640W
Fridge Freezer 150W 1 4 hours 600W
Alarm 6W 1 1 hour 6W
Modem 10W 1 4 hours 40W
Heat Pump 1250W 1 1 hour 1250W
Total 3399W

Evenings

Appliance Watts Number of uses Duration of usage Total Watts
Toaster 850W 1 3 minutes 43W
Microwave 1200W 2 3 minutes 120W
LED Lights x 10 @ 5W each 50W 1 4 hours 200W
TV x 2 @ 160W each 320W 1 4 hours 1280W
Fridge Freezer 150W 1 4 hours 600W
Modem 10W 1 4 hours 40W
Heat Pump 1250W 1 1 hour 1250W
Total 3533W

Nights

Appliance Watts Number of uses Duration of usage Total Watts
Fridge Freezer 150W 1 8 hours 1200W
Modem 10W 1 8 hours 80W
Alarm 6W 1 8 hour 48W
Phone Chargers x 4 @ 20W each 40W 1 2 hours 80W
Laptop Chargers x 2 @ 45W each 90W 1 3 hours 270W
Total 1678W

Case Study Findings

Now that we have totals for each time frame, we can determine my family’s overall usage and battery needs to cover 100% of our load using our solar battery bank.

We’ll add all three totals together: 8610W or 8.61kW.

To choose a battery, I’ll need to consider the battery’s DOD (Depth of Discharge). If I choose a battery with 80% DOD, I’ll need to subtract 20% from the overall rating of the battery.

I could consider these options to cover my usage completely:

4 x PylonTech US2000C Batteries giving me 9.12kWh @ 95% DOD.
5 x Dyness 2.4kWh Batteries giving me 9.6kWh @ 80% DOD.
3 x PylonTech US3000C Batteries giving me 9.975kWh @ 95% DOD
3 x PylonTech US3000C Batteries giving me 8.645kWh @ 80% DOD
2 x Alpha ESS 5.8kWh Batteries giving me 10.44kWh @ 90% DOD.
Chapter 6

What Solar Battery Brands Are Best?

Here’s a selection of brands which we recommend

As with the other components, the brand of the battery is closely related to the quality of the product, Solar Batteries are no different in this regard.

PylonTech

PylonTech LogoPylon Technologies, Co. Ltd founded in 2009 is regarded as the pioneer for LFP (lithium iron phosphate) battery deployed in ESS (energy storage system).

Pylontech’s battery products and solutions have been used for high-end vehicles, cloud computing systems and telecom power backups, new energy storage systems and electric vehicles.

Top features:

  • Innovative
  • High Quality
  • Specialise in Lithium technology
  • Used by companies such as Apple
  • Award-winning
  • Great value for money

View PylonTech website

Dyness

Dyness Energy StorageA relatively new player in the market Dyness have made an impressive start by rivaling the mightly PylonTech by creating similar spec lithium-ion batteries.

They have a sophisticated team of Lithium-ion experts with a specialist R&D team.

Also used in various sectors the Dyness range suits Solar applications like a glove, their PowerBox module is a big hit due to its aesthetically pleasing design at a fantastic price point.

Top features:

  • Innovative
  • High Quality
  • Specialise in Lithium technology
  • Well designed Wall Units
  • 10-Year Warranty
  • Great value for money

View Dyness website

Fusion Solar

BlueNova EnergyFusion Solar’s creators have seen the demand in South Africa for more choice when it comes to Solar Batteries. Passion for the South African Solar Industry has seen them answer this demand by finding excellent batteries that were not available in South Africa before.

Additionally, the batteries were specifically chosen for their price point and size to be able to cope with long periods of no grid supply and compatibility with quality inverters.

Their batteries have been popular thanks to their reliability and stylish design.

Top features:

  • Stylish
  • Functional
  • Realiable
  • High Quality
  • 10-Year Warranty

View Fusion Solar website

AlphaESS

AlphaESS LogoFounded in 2012, AlphaESS is one of the leading energy storage manufacturers in the world.

Their passion for green energy is evident in their excellent product range. AlphaESS offer a variety of residential and commercial storage solutions in over 60 countries world wide.

Additionally, AlphaESS ranked fifth as one of the top suppliers of Residential Storage Systems for 2020, accounting for 15% of the global market share.

Top features:

  • Good reputation
  • Long life-span
  • Excellent quality
  • Great support

View AlphaESS website

Chapter 7

How Much Do Solar Batteries Cost

What you can expect to pay

Cost of Solar Lithium-ion Batteries
We all know that the initial solar battery prices in South Africa are pretty high. But if you’re cycling a battery bank once a day and have 6000 cycles, that gives you over 16 years of battery life.

Lithium-ion prices range from just under R12,000 for a single modular battery and upwards of R53,000 for large battery banks with multiple batteries.

Below is a comparison table of lithium-ion and lead-acid 9.6kWh / 200Ah solar battery prices:

Lithium-ion

Lead-Acid

Size 9.6kWh 48V (9.12kWh Usable) 9.6kWh 48V (4.8kWh Usable)
DOD 95% 50%
Cycles 6000
6000 / 365 = 16.44
(Cycles / 1 year = Lifespan)
1350
1350 / 365 = 3.70
(Cycles / 1 year = Lifespan)
Average Cost R 61,300 R 19,100
Cost Per kWh R 6.72
(R 61,300 / 9120W)
R 3.98
(R 19,100.00 / 4800W)
Cost Per Year R 3,728.71
(R 61,300 / 16.44 years)
R 5,162.16
(R 19,100 / 3.70)
Cost Per Day R 10.22
(R 3,728.71 / 365 days)
R 14,14
(R 5,162.16 / 365 days)
NB: The above information is based on one cycle a day under optimal conditions.

You would need to replace your AGM battery bank 3 times to match the number of years that the Lithium-ion batteries give you. You will eventually spend R76,400.00 on your AGM batteries in total.

While a lithium battery price may be a significant amount to front initially, as you can see, the cost per cycle is highly affordable. And if you’re storing and using solar power rather than the grid, you’ll be saving money.

Chapter 8

FAQ

Frequently Asked Questions

Which solar battery is the best?

A lithium-ion battery is the best solar battery available because it has a longer life span and a greater depth of discharge than the AGM / gel battery variety.

When it comes to brand, stick to reputable brands like PylonTech, Dyness, Alpha ESS, Greenrich and Hubble. These brands are some of South Africa’s favourites because they are of excellent quality.

How long will my solar battery last?

How long a solar battery will last depends on the size of your battery and what you are running off of it.

The kWh rating is how many hours you have to run 1kW worth of appliances.

Here is how long a 4.8kWh battery (3.84kWh at 80% DOD) will last running 500W, 750W, 1kW and 2kW:

500W – 7.6 hours
750W – 5 hours
1kW – 3.8 hours
2kW – 1.9 hours

How to charge solar batteries?

Solar batteries are charged using either solar power or grid power. The power from these sources is fed through the inverter and then into your battery bank.

When you are ready to use the stored power, it is fed back through the inverter and into your distribution board, where it will be used to power your essential appliances.

How many solar batteries to run a house?

The number of solar batteries needed to run a house depends on your essential appliances list, and the amount of time you will run these appliances.
Below is a list of battery sizes and the sized homes they suit.

3.5kWh – 4.8kWh – Small to medium
4.8kWh – 5.8kWh – Medium
5.8kWh – 10.1kWh+ – Large to extra large

How much are solar batteries?

Solar batteries range in price from around R2500 for a 100Ah AGM battery and upwards of R50,000 for singular 9.6kWh – 10.1kWh batteries, as your add more batteries to a battery bank, the price increases.

Ask A Question About Solar Batteries

If you have a question feel free to add a comment below or contact us directly.

3 comments

  1. Anonymous

    Visitor Rating: 4 Stars

  2. Visitor Rating: 5 Stars

  3. Hi. A cycle on the lithium batteries. How’s the cycle calculated? For example, if the battery was 20% discharged, then charged again, is that a cycle or not?
    Thx

  4. Hi, if the battery is 80% DOD and it goes from 100% to 20% that would be 1 cycle, if it went to half that then that would be half a cycle.

    Hope that answers your question.

Leave a Reply

Solar Advice Deals
Sign Up to Our Newsletter
Get Solar related information and great deals available for all your Solar needs
Solar Advice Deals
Sign Up to Our Newsletter
Get Solar related information and great deals available for all your Solar needs
Solar Advice Deals
You are Subscribed!
Thank You for your subscription. We send out weekly newsletters that we know you'll love.
Solar Advice Deals
You are Subscribed!
Thank You for your subscription.