Battery storage systems

Cost: High

Difficulty: Medium–high

Impact: Low

Batteries are a great idea but right now they are too expensive to be worthwhile for many not-for-profits. For most organisations, there are better ways to reduce your carbon footprint.

Batteries have been around for a while, but in some ways they’re the super cool new technology on the block. When used with a solar system they can create a sustainable energy network for your building that produces and stores enough energy to run your building, charge your electric vehicles and potentially even return energy to the grid.

Battery storage works by storing the electricity you generate when the sun is shining on your solar panels during the day, so you can use it at night when the sun has gone down. Without batteries, any excess energy your solar panels produce during the day is sent back to the grid. In return, you are paid a feed-in tariff (FiT) per kilowatt hour (kWh) that is far lower than the amount you pay to buy energy from the grid.

There are several ways a battery can save you money. Batteries help reduce electricity costs by:

• ensuring you get maximum benefit from your solar panel system
• helping you use energy when it’s cheaper (off-peak tariffs)
• helping you manage your capacity load (only if you pay capacity charges).

Many retailers charge more for electricity at peak times. By storing surplus energy during the day for use at night, batteries can help you avoid using energy from the grid at peak times. With a battery you can coast through the expensive times using battery-stored solar energy that you harvested during the day. If your battery runs out, you’ll be using grid energy at cheaper off-peak times.

The right battery storage system may also save you money if the grid goes down. You should be able to keep essential appliances (fridges, basic energy) going so you won’t have to deal with food wastage or shut your doors if there’s a power outage.

If the cost savings sound too good to be true, that’s because there’s an important factor to consider: batteries are expensive. Although batteries are becoming more viable every year (especially with the rising cost of energy and the instability of the grid) they are still very expensive.

At the moment, a typical battery storage system would take the average household 10–15 years to pay off, once you take into the account the money you are likely to save on electricity, versus the money you are likely to spend on batteries. For organisations the cost and payback period are likely to be higher and longer.

For many organisations and households, batteries just don’t make economic sense right now. But watch this space. As they get better, more efficient and cheaper and as electricity prices continue to rise, the return on investment will become much more appealing in the near future.

There are many reasons not-for-profits are keen to invest in battery storage systems but whether or not they are right for your organisation depends on many factors:

• Can you afford it?
• Do you rely on electricity and need backup in case the grid goes down?
• How do you use energy? Will you benefit from lower tariffs if you have battery storage?
• How important is it for your organisation to be an early adopter of green technology?
• Does it make sense for your business?

Unlike solar panels, battery storage systems aren’t such a clear cut “good” investment for most not-for-profits on their journey to achieving net zero. In fact, for the vast majority, battery storage solutions represent high cost and relatively low impact.

If you are keen to invest in batteries, you need to work out what sort of system you need.

Basically this comes down to these questions:

• How much energy do you want to store? (What size battery or how many batteries you need?)
• How much space do you have to house them?
• How much (if any) excess solar energy do you currently produce? Will your current solar panel system be enough? Does your excess output make the cost of installing batteries worthwhile?

Batteries are simple to understand in theory but quickly become complicated when you get into the nitty gritty. As with solar panels, your best bet is to find a reputable and accredited supplier and lean on them to answer your questions and explain the system they are suggesting.

Battery capacity is usually measured in kilowatt hours (kWh) or how much power can a battery can hold. The separate kW (kilowatt) rating tells you how fast that power can flow from a battery.

For example, a 5 kWh battery is capable of storing 5 kWh of power, and it can discharge power at a maximum rate of 5 kW. So if your organisation has an appliance that requires 7 kW to run (e.g. a ducted air-conditioner), a 5 kW battery won’t have enough power to run it.

The other thing to be aware of, especially when comparing batteries, is the depth of discharge (DoD). A battery can never discharge 100% of the energy in it, so DoD is a percentage that refers to the actual maximum amount of energy that can be drawn from a battery. For example, a 5 kWh battery with a DoD of 80% can discharge only 4 kWh in total. In other words, a 5 kWh battery has 4 kWh of usable energy you can draw on.

The same checklist for choosing a solar panel supplier applies to battery storage installers and retailers. (See the help sheet “Solar panels”.)

The Clean Energy Council of Australia ((www.cleanenergycouncil.org.au) is a fantastic place to start when looking for battery installation quotes and accredited suppliers.

Sort of, but not really. Technically it is possible, but it’s also inefficient and slow. The best way to use the solar energy you produce is in running appliances – air-conditioners, electric hot water heaters, computers and so on.

Electric vehicles have their own charging systems. It doesn’t mean you can’t use the solar energy you produce to provide the energy needed to charge your car, but it isn’t as simple as plugging straight into your battery.

See the help sheet “Electric cars” for more information, and ask your provider to explain the best set-up for your organisation.