The second residential solar wave has started. That is home solar battery storage, these batteries allow you to store the power generated by your solar panels in batteries so your household can use this generated power at a later time such as at night or peak times when electricity costs more from the grid.

The drop in prices and technological advancements in lithium-ion battery technology  is changing the solar power revolution. This new generation of battery is more cost-effective and more efficient.

Solar battery power systems such as Tesla PowerwallsonnenBatterie Eco and Enphase AC Battery will become an increasingly common sight in solar households around Australia.

Solar powered battery storage has become a fairly new trend in solar panel systems.  Since 2015 battery storage solutions has reduce in cost significantly to the point that investments are being paid back in less than 7 years.  In fact, battery solutions are now being added as a package in new solar panel systems.

It makes sense, you now have the ability to use your own generated electricity whenever you need it without having to rely on an electric utility company.  No more paying high electric rates and no more outrageous power bills.  With new battery storage solutions you can literally be free from the electric utility companies using an off grid system.

What made this possible?  The drop in prices in lithium-ion batteries was a huge step in the right direction and over the last few years’ technology paved the way for our future.  We have had a significant boost in technological advancements, including battery storage. We now have a more efficient, effective and cheaper option to power our homes and businesses.

There are a few companies that really are top of the line in the Australian industry for solar panel system battery storage solutions.  Each of these are becoming more and more popular and will become increasingly more common in households.

  • Tesla Powerwall
  • sonnenBatterie Eco
  • Enphase AC

What type of solar panel system can a battery solution be used with?

A battery storage solution can be used with a stand-alone solar PV system or a hybrid system.  As a stand-alone PV system your system is not connected to the grid at all.  Your battery solution will generally be considered a back-up solution; therefore, the battery will charge during the day while your panels are generating power for your home as well.  At night or on a cloudy day when you need to use the battery as your source for generation, your battery will kick in as your primary form of power.  Once you are able to use the panels again, your battery will then begin charging again.  It is a pretty simple pattern of charging and relying on the battery during those times of need.

As for the hybrid systems you will have a battery back up just like a stand-alone PV system; however, you will also be tied into the grid.  This means that if you have extra generation you may be able to sell it back into the electric utility grid via a feed-in.

You need to understand the usage of your home to understand how useful a battery storage solution is.  Remember most people are at work or school during the day.  This means that the highest electrical usage is in the mornings and late afternoon and evenings.  However, solar generation will always be less in the mornings and late evenings and at night.  This is where battery storage is so effective.  When you need power the most your solar panels are not producing, but if you have a battery your solar panel generation is doing exactly what it is supposed to do – saving you money when you would be paying the most.

Until recently solar power systems have not had an efficient battery storage solution and have utilized a lead-acid battery, which is not nearly as sufficient as a lithium-ion battery.  Systems which tie into the grid will become something of the past with lithium-ion batteries becoming more suitable for stand-alone solar PV systems.  Let’s take a look at the disadvantages and advantages of battery types.

Disadvantages of Lead-Acid Batteries

Cost is the biggest reason lead-acid batteries do not work as a storage solution for solar electricity generation.  Not to mention, they require a lot of maintenance due to their hydrogen gas production during charging.  It is dangerous and requires cleaning and upkeep.  The batteries can only be charged to a certain level or problems can arise, so it’s important that the amount of charge be monitored at all times.  Unfortunately, the battery life is also quite low.  Typically only lasting three to five years with a two year guarantee from manufacturers.  If this battery makes it to ten years, you are the lucky one.  Now, if you do need to dispose of the battery it is a headache.  Understand that landfills do not take these batteries, destroying them is not an option, and most recycling centres will not accept them.  Honestly, take the advice of others and just stay away from these batteries, they are just not worth it.  There are other options that will fit your solar panel system much better.

Advantages of Lithium-ion Batteries

While there may be some areas that you need to monitor, lithium-ion batteries far outweigh lead-acid batteries.  The maintenance category is much more suitable to everyday people mainly because each cell is monitored separately from all of the others and they help each other balance out.  This mean that each cell looks out for the other by equalizing others.  The lithium-ion battery also has a fantastic lifespan of ten years minimum and unlike the lead-acid, there is no dangerous material to contaminate you, your household or system.  This also means that when it is time to dispose of the battery you may take it to a landfill.  Manufactures are working on technologies that allow them to recycle as much of 90% of the battery in the future.

The Ability to Retrofit Storage Solutions

The evolution of technology is allowing homeowners in Australia the ability to take advantage of the lower priced storage solution of lithium-ion batteries and add them to existing solar panel systems that are grid-connected.  This allows you to store your excess generated power instead sending it back to the grid.  Although your system will remain connected to the grid, you will now have a hybrid system allowing you to use the stored power when you need it, such as a cloudy or rainy day or other times when your solar panels are not producing such as at night.

A hybrid system is actually your best solution, because it is cheaper than converting to a completely off-grid system.   You will not require a large storage capacity system, just enough batteries to function during a power outage or at night.  This means you require much less stability in your system.  It is a fantastic solution to save you money from the grid and your electric utility.

Battery Terms You Should Understand

As you transition into a battery storage system, you will likely hear the following terms.  You need to understand these as you move into a hybrid system.

Usable Storage Capacity (kWh): The amount of stored energy a battery can actually use.  This is typically less than the nominal storage capacity. This means that if a battery’s totally capacity is equal to 1.2kWh and can only discharge 95% (DoD) then the usability capacity is only 1.1kWh.

Power (kW): how fast a battery can charge or discharge. This means that a battery that takes 3 hours and 20 minutes to discharge is a low power battery or an ‘energy’ battery.  A BMZ ESS battery only takes under 40 minutes to discharge making it a high power battery. A lower power battery is not necessarily better than a higher power better, but your energy needs will determine what you require.

Cycle Life & Depth of Discharge (DoD): The status of charge of a battery.  You want your battery to be able to discharge at least 90% of its capacity and recharge about 6,000 times before reach its end of life.  It is highly important that you compare these numbers when looking at battery storage options.  Most will have degradation over its life time, but pay attention to warranties.

Will battery storage become cheaper?

Costs of battery storage systems have been falling at a rapid rate and it is forecast that this trend to continue as more and more households adopt them. As an example, the cost of battery storage fell 14% every year on average between 2007 and 2014, according to a report by the Climate Council. Solar panels prices are also falling, again the Climate Council reported a 75% drop in price over the past five years with the expectation that these prices will halve again within the next five years.

The global market for solar panels and battery storage is expected to grow tenfold by 2020, the demand for battery systems like the Powerwall will have flow-on effects on prices as economies of scale really kick in.

ABC Report

Originally aired on the ABC’s 7:30 Program on Thursday 21 May, this program takes a look at how small to medium scale battery storage is set to transform the electricity market in Australia.