Common Misconceptions About Energy Storage, Electric Cars, and Solar Power

With Tesla’s recent acquisition of battery company Maxwell for over $200 Million, it’s no secret that optimal energy storage is of greater importance than ever before. The battery manufacturer with the cheapest, fastest charging/discharging, longest range, and most durable battery technology will surely dominate the electric vehicle (EV) market, among others. With batteries becoming such a significant portion of the overall direct material costs for these cars, consumers need them to last.

Seeking the optimal energy storage solution extends far beyond the EV industry. Consumers no longer want to drop a significant amount of money to replace lead-acid batteries every five years when there are alternative battery chemistries with far better charging characteristics that provide much longer life spans. Some of these battery chemistries have been around for over a century while others are state-of-the art. The nickel-iron battery chemistry, for instance, was invented in the early 1900s by Thomas Edison, and still maintains one of the longer life spans, lasting well beyond 30 years before a replacement is needed.

How do you know what battery chemistry to select for your next big purchase? For instance, what about a brand new off-grid battery based solar power system?

From a system design standpoint, batteries will have different product specifications that need to be considered for your specific application. How about that off-grid solar system installation? Well, you may just want to consider that turn-of-the-century Edison technology. Here’s why:

First, let’s clear up a common misconception; your house isn’t actually solar powered but rather battery powered with rechargeable batteries that are charged from solar panels. Your battery bank merely acts as an electric storage tank much like a hot water tank does for your hot water supply. So its important to size this battery bank to service the electrical load demand; the fridge, security, or lights your home requires. Often, this design consideration is the reason why battery based systems cost anywhere from 2-4 times more than grid-tied systems which don’t require energy storage. Because batteries are roughly 50% of the total material cost for an off-grid system.

Next to the application for which it is intended, other important properties to consider when selecting your battery solution are cycle life, temperature, environment, charge/discharge rate, maintenance, and cost. When considering battery alternatives, the majority of systems today utilize either, Lead Acid, Nickel Cadmium, Nickel Iron, or Lithium Ion. But, what many people don’t realize is that the term lithium ion is really an umbrella term for six different lithium chemistries and counting; LTO, LiPo, LiFePo4, LiFeMnPo4, LiNiMnCo, and LiCoO2. And often when people think about lithium batteries, they think their phone is going to blow up or their house is going to burn down. But those devices typically use a lithium cobalt chemistry (LiCoO2), which has the highest energy density, making them as small as possible while still holding the same amount of an energy to its counterparts. However, LiCo tends to be more unstable and doesn’t like overcharging. The Lithium iron phosphate chemistry, on the other hand, tends to be far more stable, so it has become one of the preferred lithium types for energy storage.

Back to that solar charging application; where you’re not as concerned with charge rate and size or space restrictions, the Nickel Iron battery at $1 per usable watt-hour, with a 30-year life, requiring seldom maintenance may be preferable to a Lithium Iron Phosphate battery, which is closer to $1.50 per usable watt-hour over a typical 15 life span, requiring no maintenance. And both are preferred over the Lead Acid solution, which will likely get replaced 4 or 5 times compared to their single replacement.