How Does Solar Battery Storage Work?

More than often, a relatively simple grid connected solar system doesn’t require batteries to work. Now if you think about it, the grid is in fact an unimaginably large battery. If the solar panels on your roof create more power than your home needs, then the excess energy will enter into the grid. 

Here are three good reasons why you need to add batteries to a solar system connected to the grid:

  1. You want to store the excess solar power produced during day and use it when the sun does not shine.
  2. Backup power needs to be readily available if the power grid goes down.
  3. You would like to maximise the return on your investment (i.e. charging the battery with cheap off-peak electricity and using it during peak times). Sounds like a great idea? Is this the best way to go about maximising return on your investment battery? Unfortunately, it depends on the price of electricity in your area.

Most old-school installers believed that item 1 (night time batteries) and item 2 (backup batteries) were inseparable, and that all the solar battery storage systems must provide both.

Since Tesla’s Powerwall came into the picture, smart installers have realised that offering a solar battery storage system that does not offer any backup function actually makes sense.

Why? Because it makes the system much more cost-effective. If this leaves you wondering whether you need backup power or not, continue reading this article.

The Three types of Energy Storage Systems

1. DC Coupled Storage This system senses when excess power is produced between the solar panels and the inverter and redirects it to the batteries. When more power is consumed than produced, power is realised into the inverter. One of the advantages of this whole system is that power is stored in the batteries before it is converted to an AC. One constraint of this setup is that you can not draw power from the grid and save it for later use. Supplying power in a grid outage is not a feature of this system. However, it’s ability to be upgraded in congruence with existing systems makes DC coupled storage a viable choice. 


2. AC Coupled Storage – AC Coupled Storage is perhaps the most common storage type. AC Coupled Storage is not as reliable or cost-effective as storing solar energy than DC. It has major advantages in comparison to the DC coupled storage system. However, AC coupled storage can draw electricity from the grid, enabling homeowners to purchase power at cheaper rates. This means during peak times you will not have to draw energy from the grid. This option is generally the most expensive in comparison to other energy storage systems. However, it has become a popular option amongst buyers and has proven to be reliable storage technology.


3. Hybrid Inverters – Hybrid inverters are designed for solar and batteries and have proven to deliver noteworthy benefits. Hybrid inverters occupy a mix of the properties of both DC and AC coupled solutions, meaning you can enjoy the benefits of each system simultaneously. Power is stored in the battery before it is converted to AC to save on unnecessary future conversions. Because it’s AC coupled, unique features such as battery backup and power storage are incorporated during cheaper times. Separate monitoring bundles for storage and solar systems are not required, as all monitoring is carried out from a single unit. Different problems require different solutions. This is also makes sense in the field of residential solar storage. 


Should you install a solar battery at your home?

Now that you understand how storage battery works, should install one in your home? Whether you can save money by installing a solar battery depends on how your utility compensates for your solar electricity. Most utilities offer full net metering, which implies that you receive a credit for each kilowatt hour of electricity produced by your solar panels. This means that if you install a solar battery, you will not see any additional savings on your monthly electricity bill. There are, however, many instances in which a solar battery can improve the economics of solar panels for your home and business. If your utility has time or demand charges or does not offer net metering, solar batteries can save you more.