Can Lithium-ion Take Over Lead-Acid Batteries for a Solar Energy System?

Lead-acid batteries are used heavily in solar energy systems due to two simple reasons, cost and simplicity. True, this two-century old battery type only offers a very crude maximum energy density of 75 watt-hours per liter, but it is quite easy and cheap to produce. One wouldn’t really mind the huge and bulky sizes of deep cycle lead-acid batteries if it’s designed for an entire home anyway.

But despite this apparent practicality, there is really no technical limit to the type of battery that can be used for a solar energy system. Even lithium-ion batteries, which at the moment, can be economically used only in consumer electronics and EV’s are now being considered to be used for a solar energy system.

The Lithium-ion Adoption Announcement

Sanyo made an announcement a few years ago about a new subsidiary named Sanyo Homes, which would be used to market home renewable energy systems using a combination of solar panels and lithium-ion batteries. The standard setup is a 3.78kw solar energy system, to be primarily used as back-up power for homes. Fast forward years later, at the end of January of this year, Kyocera also made a similar announcement, presenting their plans to use lithium-ion batteries for their 7.1kw solar energy systems.

Now, this might not really sound like a solid go signal for an official development race, but it is a sufficient trigger for us to seriously think of its possibilities. After all, there have been smaller applications of the same technology, so why not use it in larger scales?

More of a Doom than a Boom, For Now

We know for certain that lithium-ion batteries scores the highest in terms of being “green”, at least in the sense that it is the least environmentally harmful compared with other batteries. We also understand that lithium-ion batteries pack a whole lot more energy per unit weight. But in terms of overall practicality, these comparative disadvantages would have to be solved first.

• Deep cycle lead-acid batteries are designed to last for at least 4-6 years. Lithium-ion batteries only have life spans of about 2-3 years, before significantly losing their overall efficiency.
• Lithium ion batteries also progressively lose a bit of its efficiency every second it exists. In fact, the countdown already started as it was spewed out by the factory that made it.
• For each U.S. dollar, a lithium-ion battery could only provide 2.5 watt-hours of economic energy units. For the exact same price, a fluid based lead-acid battery can provide 18 watt-hours of economic energy units.

Summarizing all three points, lithium-ion batteries in their form today would not be able to compete economically with lead-acid batteries. The cost per unit energy is higher, you’ll have to replace it more often and the degradation had already started even before buying the battery.

Of course, Sanyo and Kyocera couldn’t have made such bold announcements if they know that their solar energy systems would just lose out economically using lithium-ion batteries. We as normal citizens (not as consumers) could probably interpret their move as a simple but important starting point to make our technologies less harmful to the environment.

Because in finding a way to make the more environmentally harmful lead-acid battery less useful, we are indirectly thinning out the overall usage and spread of toxic elements in our planet.

Source : theenvironmentalblog