The use of solar battery storage and its impact on the environment has been an essential topic of discussion.
Different factors need to be considered, such as the embedded energy cost in manufacturing the battery, its use, and end-of-life disposal. Lithium batteries are the most common type used. They have significant embedded energy, varying between 60 to 310 kWh of energy consumption, resulting in 170.2 Kg of CO2 emissions.
A battery sized efficiently and used daily could have a simple payback of 323 days, far better than the current 526.9 gCO2/kWh from grid-supplied electricity.
Batteries can reduce the household carbon footprint and maintain the stability and strength of the electricity grid. However, too much solar energy entering the grid can cause voltage and frequency fluctuations.
Do solar batteries help or hurt the environment?
This has been a debated question over recent years and is complex to assess accurately. Several assumptions need to be made when determining the environmental benefits of solar batteries and how they can affect the environment. The key considerations when looking at this are:
- The embedded energy in manufacturing the solar batteries;
- The environmental value of a solar battery in use;
- The solar battery’s end of life, if it is recycled, etc.
The embodied energy of a solar battery
Embodied energy is the energy cost or amount of energy it takes to manufacture a product and the carbon cost of that electricity. There are several different battery chemistries available with differing levels of embedded energy. For simplicity, to answer this question, we will only consider lithium batteries which are by far the most common battery chemistry used. Also, as a general comment, CO2 is generated via different forms of electricity use. Our overall calculations presented in the FAQ are general assumption calculations rather than precise calculations without any variances.
Manufacturing the solar battery
The reality is that it does take a significant amount of energy to manufacture a solar battery. There is a fair difference in the calculation of embedded energy for lithium batteries across the industry. This varies per kWh of battery capacity from around 60 kWh to over 310 kWh of energy consumed.
This may be partly due to how far back the assessment goes as to whether it is only considering the actual manufacture of the product or a complete “cradle to gate or grave” assessment. This includes all costs of mining, transport, manufacture, and end-of-life disposal. To look at this question, we will use the higher number.
Carbon costs of manufacturing
Assuming we investigate a 12 kWh solar battery. The total kWH needed to manufacture this product is 310 x 12 = 3720 kWh total electricity required to make the product. We then need to convert the kWh needed to manufacture the product to kg of CO2 for an emissions calculation.
Recent assessments have assumed that the electricity used to manufacture the batteries is from coal. This creates approx—1 kg of CO2 per kWh of electricity generated.
This would mean that based on the energy consumed above 3720 kWh of energy is equivalent to 3720 kg of CO2 generated per battery. However, the reality is that the electricity grid uses a combination of different generation forms with varying costs of carbon.
To be more accurate, the calculation should reflect this. As most solar batteries are manufactured in China, we will use the carbon intensity figures from there. According to Statistica.com, it was 549.29 gCO2/kWh in 2021. Therefore, the carbon cost of manufacturing a lithium-ion solar battery can be better represented as 549.29g x 3720 kWh. Giving us a total of 2043 kg of CO2 produced in manufacturing one home storage battery.
Is my solar battery sized correctly?
If the battery is sized efficiently, it should be fully cycled (used) every day. This means a 12 kWh battery will charge and discharge around 11 kWh. As one will always retain some charge to prolong its life.
In Australia, the carbon intensity of the grid-supplied electricity from Statisitica.com was 526.9 g CO2 created per kWh of electricity. So if the battery works in partnership with a solar system and is there to capture renewable energy and replace coal-fired energy. Then the question is – how many days will it take for the battery to capture enough renewable energy equal to the CO2 it took to make the battery?
2043 kg of CO2 being CO2 generated to make the battery is equivalent to the CO2 generated from generating 3877 kWh of coal-fired electricity in Australia.
We established that the battery per day supplies 11 kWh. So it will take = 352 days to hold the electricity equivalent to the electricity required to manufacture the battery. In short, a solar battery will take less than one year of operation in combination with solar to regain its carbon footprint.
This calculation nevertheless makes a huge additional assumption. The assumption is that we have a large solar system that generates 11 kWh of additional electricity to be exported daily. The system has export control, meaning that the 11 kWh of additional renewable energy lost is only preserved due to the battery.
How much CO2 do we generate per kWh over the life of the solar battery
Most lithium batteries have a 10-year plus warranty and are expected to be used longer than the warranty period. So if we seek to calculate the battery’s carbon benefit, we must assume how long it will last. Then we can calculate the carbon cost per kWh of energy the battery uses.
As batteries degrade over their lifetime, even if we assume a 10-year lifespan, we can not simply say 11k Wh per day benefit x 365 days x 10 years is 40,150 kWh. So instead, let’s use 35,000 kWh of solar over the battery’s life to account for the degradation.
To generate 35,000 kWh of electricity in Australia in our current electricity mix. It would generate 35,000 x 526.9 g of CO2, which is 18,441 kg of CO2. The solar battery needs 2043 kg of CO2 generation to be manufactured. So the net benefit of the battery in CO2 reduction would be 18,441 – 2043 = 16,398 kilograms of CO2 avoided.
To look at it from another angle, 35,000 kWh over ten years is available to the household for the equivalent of 2043kg of CO2 generation. This is 58.37 g of CO2 for each kWh of electricity. This is only around 10% of Australia’s CO2 generated using conventional coal-fired electricity.
So from this perspective, solar batteries are good for the environment. As long as they capture renewable electricity, which would not have been able to be used without a battery (export-controlled)
Value of a solar battery to the grid
It has also been argued that from an environmental perspective, solar energy is better than a battery to store it. A solar system that does not have a battery will export that electricity that is not consumed on-site when it is generated to the grid. This can then be used by neighbouring properties, displacing fossil fuels, as long as the system is not export-controlled.
Using a battery to store the electricity in the home could then be seen as adding a CO2 cost to the battery. From an environmental perspective, it is not required when solar electricity can be sent straight to the grid and used. This may have been valid in the early days of solar when the amount being fed back into the grid was small. As more solar power is installed, more electricity is fed back into the grid. Increasingly, this is different.
How are batteries affecting the grid?
The grid is seeing increased difficulty in managing the increasing and variable flow of solar into the grid and maintaining the stability and strength of the electricity grid overall. Too much solar entering the grid creates voltage and frequency fluctuations which can cause power surges, blackouts etc.
As a result, nationwide networks limit the amount of solar that can be sent back to the grid to maintain the system’s strength. This means solar electricity is wasted because it can’t go anywhere. In addition, the networks will require significant investment in the grid to manage the solar more efficiently. This will be both expensive and have its own carbon cost from the materials used etc.
The alternative is for homeowners to install batteries to store their self-generated renewable energy. Then use it on-site, increase their self-sufficiency and reduce the household’s carbon footprint.
Importance of batteries for our future
Suppose the grid is to increase the penetration of renewable energy further and eliminate fossil fuels. The electricity going into the grid needs to be dispatchable/ controllable. Therefore, batteries become increasingly essential to store solar electricity to be used when required in the home. But also to be able to be sent back to the grid when needed (and potentially get paid for this with a VPP).
As such, solar batteries will become more critical in transitioning to a 100% renewable/sustainable electricity grid, increasing their value to the environment.
However, if you install on-grid batteries, you will not instantaneously cut world emissions in half. People are buying these batteries to prepare for the future, and when they do buy them, they feel they have contributed to reducing emissions in the future.
It is estimated that by 2030 there will be 11 million tons of lithium-ion battery waste. This means that significant investment funds are required to improve the economies of battery recycling. Otherwise, they will be placed in landfills and pose a harmful threat to the environment even after they are helpful.
Solar batteries can also negatively affect the environment if they are not recycled. However, lithium batteries are recyclable at the end of their useful life. The various precious metals, including lithium, cobalt, nickel, copper etc., can be broken down from the batteries to be reused. The simple fact is that until now, the volume of lithium batteries to be recycled has been low due to it being a new technology.
Still, as the batteries reach a critical mass, especially with EVs coming into the mix, recycling plants are being developed fast.
While the calculations above are general and simple, with some assumptions, overall, they are valid. Batteries do and will have a positive impact on the efficiency of the home. As well as the grid in the transition to a 100% sustainable electricity grid. They are also a “weapon” against climate change.
Unfortunately, the world is still largely reliant on fossil fuels, and practically everything you purchase has a substantial carbon footprint due to CO2 emissions from manufacturing and transportation.
Batteries are no different. Manufacturing emissions from batteries will decrease as the globe utilises more renewable power and recycled materials.
Batteries combined with solar will be able to aid us in becoming more independent from the grid.
So to answer the question, solar batteries impact the environment in production and end-of-life. They can benefit the environment by reducing our dependence on a coal-power-generated electricity grid. ever.