When we think of batteries, the AA penlight batteries come to mind that we use in our TV remotes or kid’s toys. Most of the time these batteries are the disposable type where we use them until they lose their charge, then throw them away. Not without environmental consequences though.
Then there’s the rechargeable type of battery; a car battery is an excellent example of this.
What is a battery though? It’s a device that stores energy. You take energy from one source and save it for later use.
Batteries work by taking advantage of complex chemical reactions. Some of them are quite dangerous actually! With exploding batteries, a possibility but luckily not commonplace!
Without batteries, the world would be a very different place.
No TV remotes for starters, that would be sure to cause many challenges when it comes to family prime time viewing! Nor would we have electrically powered golf carts and what about cars or even worse your SMART phone?
Who can we thank for inventing the first battery?
The first real battery was developed in 1800 by Italian physicist Alessandro Volta. This is where the electrical term Volt comes from. A Volt describes the electrical potential of a circuit.
Volta’s battery was a fairly simple device.
It consisted of pairs of copper and zinc discs piled on top of each other, separated by a layer of cloth or cardboard soaked in brine. It was called the Voltaic Pie.
In 1859, the first rechargeable battery came into existence, the lead-acid battery. Unfortunately, the lead-acid battery has seen very little innovation since.
There are severe drawbacks to lead-acid batteries though. They are heavy and bulky, they’re corrosive, and you can only use 50% of the energy content stored in the battery.
Most rechargeable batteries in the modern world today are based on lithium-ion technology.
The challenge with renewable energy and this includes Solar PV, is that the electrical energy generated varies depending on some factors, such as weather, time of day, and shading.
The electrical output of your solar PV system increases as the day goes by and normally peaks during the middle of the day before dropping off in the afternoon. Therefore, you are producing the most electrical power when you probably aren’t home to use it!
Intelligent SMART Energy systems such as the SMA Home Energy Manager as an example are available on the market that can control your appliances and turn them on when you aren’t home, and your solar power is at its peak. Then there’s also the feed-in tariff where excess clean energy produced and not used is fed into the grid, and the prosumer is offered a financial incentive. Albeit the feed-in rate usually is less than the retail cost of grid electricity.
A better alternative would be to store that energy for later use.
Incorporating energy storage solutions into your home Solar PV system has many advantages.
It allows you to store the clean energy your rooftop solar system produces for peak periods such as the early morning during the breakfast run or in the evenings when preparing meals, watching TV, switching lights on etc.
An Energy Storage System (ESS) can also supply you with backup power, in case of a grid outage. Or even better, allows you to go completely off-grid and cut your connection to the utility grid.
Should one invest in an ESS or Energy Storage System? Well, it’s not for everyone, and it depends on what you want to achieve. Spending on an Energy Storage System is expensive and does add to the cost of the overall Solar PV system. So, it’s recommended that one weights up the values and perform a cost-benefit analysis before investing.
An example of this is if you live in an urban environment with a reliable electrical supply from your utility and a decent feed-in tariff, then it might be worthwhile to opt for a grid-tied system instead.
Numerous different types of rechargeable Solar PV batteries are available on the market today. The underlying technology of these batteries hasn’t changed much since they were first invented.
Of all the types of Solar PV batteries available, the most exciting development in battery technology is the Lithium-ion battery, and it holds great potential in the Energy Storage market!
Lead-acid was the first rechargeable battery to be invented and was able to provide energy discharge for more extended periods of time. It consisted of layers of cells with a lead grid lattice, in which the lead oxide paste was pressed. A few drawbacks of lead-acid batteries, though, are that they are heavy and have a short lifespan of 4 to 5 years. You can only discharge them to 50% of their capacity too. Meaning a great deal of energy is being wasted, discharging them more than 50% shortens their lifespan.
Nickel-cadmium is another type of battery that can be used in solar PV systems. It was invented in 1899. One significant advantage it has over lead-acid is that it has a higher energy density than lead-acid batteries. Meaning you can store more energy in it and it has a longer lifespan than lead-acid batteries. However, it’s still prone to low efficiencies.
The battery contains nickel and cadmium electrodes soaked in a potassium hydroxide solution. A disadvantage of these batteries is that cadmium is a highly toxic corrosive chemical, so the safe recycling of these batteries is expensive.
Nickel-iron batteries consist of nickel(III) oxide-hydroxide positive plates and negative iron plates, with an electrolyte of potassium hydroxide. It is a robust battery and tolerant to abuse such as over-charging and over-discharging. It’s often used in backup situations where it can be continuously charged.
Some disadvantages, though, are its poor charge retention and the high cost of manufacturing.
Lithium-ion batteries are a new technology. They are much lighter than lead-acid batteries, it has a higher energy density and you can use more of the energy stored. The lithium-ion battery was invented in 1980 by Professor John Goodenough.
It doesn’t have the same limitation as lead-acid batteries whereby it can only be discharged to 50% of its energy storage capacity. The latest Lithium-ion batteries developed can be released to up to 95%!
As for the energy density of this battery. Consider that a lead-acid battery can store only 25 watt-hours per kilogram for starters. A lithium-ion battery can save a whopping 150 watt-hours of electricity in 1 kilogram of battery.
The development of the Lithium-ion battery has been a real game-changer for the energy storage industry has already revolutionized the portable electrical sector. Now consider the impact it’s having on the Solar PV market?
One drawback of the technology is its current cost. Although with economies of scale it’s expected that production costs will come down in the next few years. Another disadvantage is that lithium-ion batteries are more sensitive to high temperatures, which results in faster battery degradation.
Energy Storage is considered to be the Holy Grail for Renewable Energy and as such a lot of R&D investment is going into the development of new battery technology.
Batteries are already being developed in the lab that can be charged in minutes instead of hours and have much higher energy densities with longer lifespans.
Expect to see exciting developments in this space in the coming years!