Solar batteries store the excess energy that solar panels produce so that they can be used when the sun isn’t shining, be it at night or during inclement weather. If you already have a solar power system, or your organisation is considering investing in one, a solar battery as part of the installation may enhance performance and maximise energy use.
CORENA works with a wide range of non profits, providing technical advice and interest free loans to fund solar panels, energy efficiency and other initiatives in order to help organisations reduce carbon emissions and save on their energy costs.
CORENA hasn’t often loaned to battery projects in the past as it is usually difficult for them to pay for themselves. However, as power prices increase they are becoming increasingly viable for many organisations particularly those with evening operating hours and “time of use” or “demand” tariffs. One example is our project with Capri Theatre. They use a significant amount of their electricity in the evening and their particular electricity tariff allows them to save money with a battery as it allows them to avoid purchasing power at this high demand time when it is most expensive.
CORENA also considers the level of carbon emission reductions from projects. Batteries don’t reduce carbon emissions on their own. However with the increasing uptake of renewables in many states, batteries now allow for abundant solar electricity to be “soaked up” in the middle of the day, reducing the use of power from the grid in evening peak times, playing a part in allowing for greater uptake of renewable energy and decarbonising the grid as a whole.
With one of our key projects now including battery technology, we’ve put together this guide about the different kinds of solar batteries available and why, when and how to use them effectively.
Types of Solar Batteries
There are various types of solar batteries available on the market, each with its own advantages and disadvantages. Choosing the right kind of solar battery for your project depends on the requirements of your particular system as well as the specific needs and budget that you have available.
- Lead-acid batteries – these have been used in off grid applications for many years. However they are bulky, have higher maintenance requirements and are inefficient compared to newer battery types.
- Lithium-ion batteries are efficient, lightweight and compact, requiring little maintenance, but can be fairly expensive upfront. Lithium nickel-manganese-cobalt (NMC) is a common Lithium Ion chemistry used in many batteries as well as others like Lithium titanate. Another common chemistry is lithium iron phosphate (LiFePO, or LFP) which is increasingly being used in cars and stationary batteries as it has a lower risk of fire.
- Flow batteries – might include options such as vanadium redox flow batteries, make use of liquid electrolytes stored in separate tanks. They have a number of benefits over Lithium Ion batteries including being less flammable and experiencing less degradation but do take up more room.
Battery chemistries are rapidly evolving, becoming safer and more efficient all the time. There are various other types of batteries available, including saltwater batteries, hybrid batteries that combine different technologies in one; nickel-ion batteries; and sodium-ion batteries.
However, currently, lithium-ion batteries are preferred for most smaller-scale installations thanks to their high energy density, long lifecycle, and ease of maintenance—ideal for the average user.
Why Use Solar Batteries?
One of the benefits of using solar batteries is that they help you make the most of the energy that is generated through your solar panels. Solar panels alone are only effective when there is sufficient sunshine to provide power. Batteries, however, can help you maximise that electricity use by storing it rather than wasting it.
Batteries can help you reduce your ongoing power bills even further than just solar panels on their own. They are also very important in allowing for more renewable energy to be added to the grid.
Another advantage is they can provide a level of backup power in blackouts. However not all batteries do and some may only provide power to certain appliances (eg your lighting or power outlets) but may not run your entire building. If this is a feature you wish to have you need to discuss this carefully with your installer to make sure you get what you need.
When Should Solar Batteries Be Used?
A battery could be beneficial to your organisation if;
- You generate significant excess solar power with your existing system or, if you are installing a new system, your roof space allows you to install a solar system that is big enough to generate excess solar. You need to generate enough excess solar to charge your battery sufficiently every day.
- You use a lot of power in the evenings. Offices, for example, typically don’t use a lot of power at these times.
- You are already, or have the ability to shift to, a time of use tariff or demand tariff. A time of use tariff charges you different amounts for using power at different times of the day. So for example you may get charged 30c/kWH for using power from 9am-3pm but 50c/kWh from 3pm-9pm and only 15c/kWH overnight. This means that the battery would allow you to avoid using power in the expensive period while still accessing cheap power at other times of the day. Some organisations may also be on a demand tariff. Demand tariffs usually consist of a demand charge based on your maximum electricity demand at times when the grid is experiencing very high use. They have been designed to encourage less electricity use during these peak demand times. A battery is able to help you reduce your peak demand and therefore can save you a lot of money on these tariffs. Shifting to one of these tariffs can, if you are not careful, increase your bill so it is important to look at your existing energy use and work out if it is better to switch. For small organisations looking at a time of use tariff, CORENA may be able to help you do this. Larger organisations with a demand tariff may need the assistance of an energy consultant to do this sophisticated analysis.
- You can participate in a Virtual Power Plant (VPP). Your battery has the potential to unlock even more cost savings if you participate in a virtual power plant. A VPP can aggregate the capacity of your solar and batteries and sell the power and grid services your solar and batteries provide. A Virtual Power Plant may charge or draw on the power in your battery at certain times, reduce export of your solar or even switch it off all together in certain situations. You are then paid for providing these services. While many people don’t like the idea of giving up some control of their battery it is actually quite a powerful way to allow more renewable energy into the grid and maintain grid stability. However make sure you read the terms and conditions carefully, some VPPs are better deals than others. It is also important to check that they will leave you a reserve battery capacity (ie never draw down your battery beyond a certain level) so there is energy left for you when you need it!
How To Use Solar Batteries Effectively
The first thing you need to do before installing a solar battery system is take inventory of your organisation’s daily electricity consumption. This will help you determine what size battery system you need. By completing an energy audit you may find that there are other more cost effective things you could do to reduce your energy use first or shift your evening energy use to the middle of the day. That way you are not spending extra installing an unnecessarily large battery.
Learn more in Energy Efficiency Audit Guide For Non Profits
The next step is to choose a good Clean Energy Council Accredited Installer to size your battery for you. Ideally they should access data from your smart meter which tells you how much power is being used every 1-30 minutes (depending on your smart meter). In this way they can get an accurate understanding of how large your battery needs to be to cover your evening and night time energy use.
To size a battery to be completely off grid it would need to be very large so it has enough electricity to power all of your needs in the rare situations when there may be 3-4 days of bad weather. This is usually cost prohibitive unless you are constructing a new building and the cost to upgrade your power supply or bring power to the site is going to be very high. In this case an off grid battery might be cheaper.
Most people are installing batteries to maximise their cost savings so the installer will size the battery to meet most of their daily electricity needs and for the odd occasions when there is bad weather for a number of days they draw from the grid. This means they only need a smaller battery which costs less upfront but are still seeing the majority of savings.
Sizing the battery is a balancing act between these things and the installer should use a model to work out what is best for you. CORENA can double check their battery sizing to make sure it seems reasonable.
Most modern battery systems come with customer-facing applications that allow you to see your energy usage in real time so that you can properly manage your consumption and match it with the solar generation capacity. This is not just useful for monitoring the performance of your battery but also managing your overall energy use over the longer term.
Solar Panels & Battery Funding for Non Profits
Apart from applying for grants and rebates, here at CORENA, we can provide free technical advice and zero interest funding to community organisations looking to reduce their emissions and green their energy consumption. We are funded by donations from local community members across Australia. Donations help us fund:
- Solar Panels
- Energy Efficiency
- Getting Off Gas – Replacement of fossil gas appliances with electric alternatives
- Electric Vehicles
- A combination of the above
You don’t pay any interest on your CORENA loan, and the quarterly loan repayments are set to be a little less than the savings on your operating costs averaged over a year. This means you are never out of pocket. After your loan is fully repaid, you will reap the full financial benefit of having lower operating costs.