Are you considering a battery storage option for your solar system? There are four main classes of solar battery storage options. Let’s take a look at the different options and their advantages and disadvantages.
Flooded lead acid batteries, also called “wet cell” lead acid batteries, are the cheapest up-front solar battery storage solution and are akin to the battery you might have in a boat or car. They’ve been around for decades and are what you would commonly see used on solar arrays in the developing world. And while they are inexpensive, they have a lot of disadvantages. First of all, they emit toxic fumes, so they need to be in a well-ventilated space. They require regular maintenance (watering, cleaning, and equalizing) and they can overheat and burn up. These batteries are much better suited to a completely off-grid solution, not as an emergency backup battery.
Deep-cycle Absorbent Glass Mat (AGM) Batteries
AGM technology first became widely used in the 1980s in a military capacity. Inside these batteries, sulfuric acid is absorbed by a thin, fiberglass mat, rendering the battery spill-proof. The plates can either be made flat so the battery resembles a standard flood lead acid battery or they can be rolled into a cylindrical cell. AGMs are essentially still a lead-acid battery, but they give steady power output over an extended period of time and have fewer maintenance requirements. They don’t give off fumes, nevertheless, you don’t want them inside your house as all lead-acid batteries have the capacity to create a fire.
Now, we are getting somewhere! Lithium-cobalt batteries are the ones found in the Tesla Powerwall and in the Tesla vehicle, for that matter. Lithium blended with cobalt is also toxic, but only if burned. These batteries don’t give off any fumes and are generally considered safe unless the cell is punctured, which is very rare.
The only downside here is that the lithium-cobalt battery has an 80% depth of discharge (DoD), meaning that only 80% of its capacity can be used before it needs to be recharged or you run the risk of not being able to recharge it at all. Luckily, as a customer you won’t have to worry about this as these batteries are equipped with a battery management system. But what it means is that a battery rated for 13kwh actually only has about 10kwh of usable storage capacity. The other limitation of this battery is that it has a max heat tolerance of 113 degrees Fahrenheit, and in almost all cases the warranty will become void if it crosses that threshold. Tesla handles this by building in an internal cooling system.
Generac offers a lithium-cobalt solution that is more affordable than Tesla’s PowerWall. Generac’s cabinet can house between two and six batteries and also comes with a venting/cooling system and controller. Coronado Solar installs Generac battery solutions, so feel free to reach out to us for more information.
Lithium ferro phosphate batteries (LFP or LiFePo)
These are the creme de la creme of battery solutions. They come plug and play ready in a nice cabinet just like the Tesla Powerwall. The difference is that with an LFP, you get a 100% DoD, meaning you get to use their full-rated capacity! They are much more heat-tolerant and use 70% less lithium, which is more sustainable considering the Earth has a limited supply of this element. Enphase offers an LFP battery that our customers have been very happy with (Enphase is also the manufacturer of the #1 inverter system in the world).
Another perk of their solution is they use a Smart Switch that allows you to pull power simultaneously from your roof and from the battery. As the sun goes down and your solar system output is waning, the batteries will automatically top you up so you don’t even notice. LFP batteries are long-lasting and a great solution!
So what’s next for solar batteries?
If you are interested in battery technology you might be wondering what the future holds. Honestly, the future of solar batteries is probably not batteries at all, but hydrogen. But that’s a chat for another day…
Let us help you with your solar or solar/battery solution. Visit www.coronadosolar.net and click on “Request a Quote”.