Solar battery storage is it worth it?
Solar battery storage
A solar battery captures unused solar power generated during the day, used later at night and on low-sunlight days. Solar installations that include batteries are becoming increasingly popular. There is a natural attraction to being independent of the grid: for most buyers, it isn’t just an economic decision but an environmental one. For some, it expresses their wish to be independent of energy companies.
If your solar panel array and Battery included are large enough, you can run your entire home on solar power. Using the energy from your Battery can be cheaper per kWh than using electricity from the grid, depending on the time of day and electricity tariffs in your area.
Grid-connected vs off-grid
Your home can be set up for electricity supply in four main ways.
Grid-connected solar (no solar battery storage)
The most general set-up for homes with solar panels. The solar panels supply power throughout the day, and the home typically uses this power first, resorting to grid power for any extra electricity needed on low sunlight days, times of high power usage and at night.
Grid-connected no solar
The most generic set-up, where all of your electricity comes from the primary grid. The home has no solar panels or batteries installed.
Off-grid
This system does not connect to the primary grid. All the home’s power comes from solar panels and possibly other types of power generation, e.g. wind. The Battery is the primary energy source at night and on low-sunlight days. The final backup is usually a dieseled-powered generator, which may also kick in when there’s a high demand for power (such as a pool pump starting up).
Off-grid systems generally are much more complex and expensive than grid-connected systems. They need extrasolar and Battery capacity more than your typical grid-connected system and might also need inverters capable of higher loads to deal with peak demands. Homes run off-grid need to be particularly energy-efficient, and the load demand must be well-managed during the day.
Off-grid systems usually only make sense for remote properties where the grid connection isn’t available or would be too expensive to install.
Grid-connected solar + Battery, also known as a “Hybrid System.”
These have solar panels, a hybrid inverter (or multiple), a battery, and a connection to the primary grid. The solar panels supply power throughout the day, and the home generally uses the solar power first, using the excess to charge the Battery. During high power usage or night and low sunlight days, the house draws power from the Battery and, as a last resort, from the grid.
What happens during a blackout?
For most grid-connected systems, having a battery doesn’t necessarily protect you during a blackout. You can still lose all power to your home, despite having solar panels producing capacity and a charged battery waiting. This is due to grid-connected systems having an “anta-islanding protection”. During a blackout, the grid and the engineers working on the lines must be protected from “islands” of electricity generation, e.g., solar panels, pumping power unexpectedly into the pipes. For most solar PV systems, shutting down completely is the simplest way to provide anti-islanding protection. When the grid senses a blackout, your solar PV system shuts down, and you have no household power.
However, more sophisticated inverters provide anti-islanding protection during a blackout but keep solar panels and batteries operating, leaving the house with some power. You can expect to pay more for a system like this, as the hardware is more expensive, and you may need more Battery and solar capacity than you think to run the house during a blackout. You may also choose only to allow critical household circuits, such as the fridge and lighting, to operate in this situation.
Battery specifications
Below are the key specifications for a home battery.
Capacity
How much energy the Battery can store is usually measured in (kWh) kilowatt-hours. The nominal capacity is the total amount of energy the Battery can hold; the usable capacity is how much of that can be used after the depth of discharge has been factored in.
DoD (depth of discharge)
Expressed as a percentage, this is the amount of energy that can be safely used without accelerating battery degradation. Most batteries need to hold some charge at all times to avoid any damage. Lithium batteries can be safely discharged to 80-90% of their usual capacity. Lead-acid batteries can usually be discharged to 50-60%, whilst flow batteries can be entirely removed at 100%.
Power
How much power in kW (kilowatts) can the battery deliver? The maximum power is the most the Battery can provide at any moment, but this burst of power can usually only be sustained through short periods. Continuous power is the amount delivered while the Battery has enough charge.
Efficiency
How much will the battery store and put out again for every kWh of charge? There is always some loss, but a lithium battery should usually be more than 90% efficient.
Total number of charge/discharge cycles
This is how many cycles of charge and discharge the battery can perform before it reaches the end of its life. Lithium batteries can usually last for several thousand cycles.
Years of cycles
The expected life of a lithium battery can be rated in cycles. The lifespan should also state the desired capacity level at the end of life; lithium batteries usually comprise about 60-80% of the original capacity.
Ambient temperature range
Batteries are sensitive to temperature and need to operate within a specific range. They can degrade or shut down in very cold or hot conditions.
Types of Battery
Lithium-ion
The most common type of Battery being installed in homes, these batteries use similar technology to their smaller counterparts in laptop computers and smartphones. There are multiple types of lithium-ion chemistry. A common type used in home batteries is lithium-nickel-manganese-cobalt (NMC), used by LG Chem and Tesla.
Pros
- They can give several thousand charge-discharge cycles
- They’re suitable for a wide range of ambient temperatures
- They can be discharged heavily (80-90% of their overall capacity)
- They should last for 10+ years in regular use
Cons
- End-of-life may be an issue for large lithium batteries
- The batteries need to be recycled to recover valuable metals and prevent toxic landfill, but large-scale programs are still in their infancy. As home and automotive lithium batteries become more common, recycling processes are expected to improve.
Lead-acid, advanced lead-acid (lead-carbon)
The lead-acid battery technology that helps start your car is also used for larger-scale storage. It’s a well-understood and effective battery type. However, without a significant performance development or price reduction, it’s hard to see lead-acid competing long-term with lithium-ion or other technologies.
Pros
- Established disposal and recycling processes whilst also being relatively cheap
Cons
- Sensitive high ambient temperatures, which can shorten their lifespan
- They have a slow charge cycle
- Bulky
Flow battery
One of the best alternatives to lithium-ion, this type uses a pumped electrolyte (such as zinc bromide or vanadium ions) and chemical reactions to store charge and rerelease it. However, this is currently unavailable in Australia.
Pros
- They can be discharged to 100% of their capacity with no residual discharge, meaning they won’t lose charge over time.
- Operate well in high ambient temperatures
- Easy to recycle
- Should last for 10+ years
Cons
- As they’re a new technology, they are more expensive than lithium-ion
- Don’t tolerate cold that well (below 15°C)
- Require frequent maintenance
Other types available
Battery and storage technology is in a state of development. Other technologies include the Aquion hybrid ion (salt water) battery, molten salt batteries, and the recently announced Arvio Sirius supercapacitor.
How long do solar batteries last?
Most solar batteries should be able to last ten years or more under normal usage and not be put through extreme climates (temperatures). Most batteries have a ten-year warranty and should be able to outlast that.
Are solar batteries worth it?
Many people invest in home battery storage or ensure their solar PV systems are battery-ready. The price of solar batteries continues to drop and is becoming a more popular investment for homeowners. We recommend that you ensure your Battery has a ten-year warranty, and we will provide continuous support along the way.
Rebates, subsidies and virtual power plants
Currently, we do not have any rebate schemes for battery systems in Western Australia. We will continue to update this as more information becomes available.
Feed-in tariffs
Remember to include the feed-in tariff when you’re adding up whether a battery makes sense for your home. This is the amount you are paid for any excess power generated by your solar panels, which is then fed into the grid. You’ll forgo the feed-in tariff every kWh diverted instead into charging your Battery. This should be considered as an opportunity cost when installing your system.
Solar battery storage costs
Costs vary significantly for solar batteries; however, the higher the capacity of the Battery, the higher the price usually is.
Below are some typical battery costs for standard capacity sizes, which cover just the Battery. The installation will include an additional cost.
- 6kWh: $4,000 – $9,600
- 10kWh: $7,600 – $13,500
- 13kWh: $9,600 – $15,000
Generally, you will need to add the cost of a new inverter and extra cabling for connection. It can be more cost-effective to buy a battery as part of a brand-new solar panel system than to fit it into an existing one.
Your home insurance
Your solar system (Battery, inverter, panels) is part of your house, meaning your home insurance covers it. However, you should ensure your home’s insured amount is increased to cover the replacement costs of the solar system.
At Westsun Energy, we have over ten years of experience in the solar industry. To learn more about solar battery storage, please get in touch with us with any questions or queries. Our team of professionals will be more than happy to help you find the solution you seek.
