When it comes to designing solar-plus-storage systems, small mistakes can be very costly, says Christopher LaForge, CEO of Great Northern Solar and an NABCEP-certified PV Installation Professional Emeritus.
He should know. The instructor of HeatSpring’s “Designing PV Systems with Energy Storage” course, LaForge has been called in more than once to repair the damage wrought by a badly-designed system.
Proper Design Can Prevent Disaster
For example, he saved the day after a major mishap that occurred on a large-scale family lodge located on an island. The battery system had been designed improperly and not tested adequately, and its automatic charging system failed.
“The battery got overcharged to the point where the electrolyte boiled off and the battery plates warped,” says LaForge.
Once battery plates warp, they can arc. This happens in an environment that creates a lot of oxygen and hydrogen, he explains.
Close by, a propane generator was hooked up to a huge propane tank. Luckily, the basement where the equipment was located was very leaky and provided enough airflow to prevent an explosion, he says.
“If this system had been in an efficient home, the whole house could have blown up,” he says.
The bottom line, says LaForge: “Learn proper design. Get educated!” His “Designing PV Systems with Energy Storage” course is meant for installers, designers, engineers, and architects. In addition, it’s for commercial PV-plus-storage users who want to be in the know about potential design flaws.
Create a Cost-Effective System
Along with learning about how to design a safe system, you need to learn how to create a cost-effective one. Given all the new battery technologies available, it’s not so easy to sort out which ones to choose.
However, based on his 29 years in the industry, LaForge has strong opinions about which systems to select now—and which to consider in a few years. In his HeatSpring course, he teaches students about the strengths and weaknesses of the different technologies. He focuses on which technologies work best in different types of applications.
“Right now, it generally makes economic sense to use time-tested, lead-acid batteries. But lithium-ion batteries—employed in the Tesla Powerwall and other high-profile applications—are quickly catching up,” says LaForge, who was named IREC’s 2016 Master Trainer of the Year.
“Most people who look into this see lithium ion as the best choice. Economically, it’s moving there quickly but isn’t quite there,” says LaForge. Here’s why: “The amp-hour-per–dollar-per-year ratio is lower for lead-acid batteries.”
LaForge says that to ensure lead-acid batteries last for many years and are the most economical, you need to care for them, which requires a gentle, yet nerdy touch.
“Some of my friends on the cutting age of using these technologies scratch their heads when I say lead acid is better for the short run,” he says.
A shorted-lived deep cycle lead acid battery will last only about five to 8 years. “I have had them last 28 years because I know how to take care of them. It’s a nerdy thing I’m good at,” LaForge says.
Choose Lead-Acid Batteries Now and Lithium-Ion Batteries in Five Years
Right now, LaForge generally advises clients to purchase the less expensive, shorter-life, true deep cycle lead-acid batteries and switch them out with lithium-ion batteries in about five years. That’s because lithium-ion batteries last longer and their price is expected to drop significantly in the next five years.
The price plunges are anticipated thanks in part to Elon Musk and his Tesla gigafactory, which has a planned production capacity of 35 GWh. “This is nearly as much as the entire world’s current battery production combined,” according to the Tesla website.
The factory’s planned annual battery production is nearly as much as the entire world’s total battery production. Manufacturing so many batteries will reap economies of scale, allowing Tesla to make products available to more people, Tesla says.
“Now that lithium ion is seeing larger numbers of products in the market and huge increases in manufacturing because of the Tesla gigafactory, we will see prices come down,” he says.
Whether lithium-ion batteries come from Tesla’s gigafactory or other suppliers, there’s more than one to choose from. In fact, buyers have about five different types to choose from, each with its own chemistry, advantages, and disadvantages.
The most competitive are lithium-iron-phosphate batteries, produced by SimpliPhi and other manufacturers. Also competitive are lithium-manganese cobalt batteries, says LaForge. Lithium-manganese cobalt boasts a longer life and higher discharge capacity, while lithium-iron-phosphate has more stable thermal characteristics, which means it’s harder to start on fire.
Worries about battery fires are common in the industry, and it’s important to understand that the battery’s chemistry is not the only fire deterrent, says LaForge.
Pay Attention to the Battery Management System
What’s also important is the battery management system, which is included in every lithium-ion pack and stops the batteries from overcharging or over discharging.
“You have to keep them from discharging and charging too much. That’s how we keep the battery safe,” says LaForge. ”I’ve always been a promoter of small local companies until you start talking about batteries. Go with companies that have horsepower behind them—big companies,” he advises. These companies will produce the safest batteries, he says.
While LaForge specializes in combining renewable energy with energy storage, sometimes a battery alone will reap substantial savings, he notes.
“Let’s say you have a small- to middle-sized commercial site, and your peak energy demand is 35 percent of your bill. With batteries, you can cut that in half. It’s revenue and cash flow.”
For example, LaForge is working on a peak-shaving project at the Hartley Nature Center in Duluth, Minn. When he came on board, the center was experiencing 30-kW peaks. With funding from Minnesota Power for a battery system and working with several local professionals, LaForge and the team cut the peak to 15 kW with energy efficiency and a smart battery system.
“Our target was 20 kW, but the intelligence of the system and some hard-working team members allowed us to get the peaks down below 15 kW,” he says. That project is still fairly new and data is still being collected.
In spite of the impressive savings potential of installing smart batteries without renewable energy, LaForge isn’t in this business to simply shave peak demand. He’s in it for the renewable energy and all its environmental benefits.
“We’re confronting the biggest environmental problems in the history of the planet. Global warming is a fact. If we don’t confront it quickly, generations to come will have much diminished lives. We need to actively reduce our carbon impact. Renewable energy and batteries can be a big asset to doing that,” he says.