A Complete Guide to Storing Solar Energy

Getting solar panels is only part of the equation when it comes to installing renewable and sustainable power for your home. Energy storage is just as important as energy generation if you want an uninterrupted supply of electricity.

You need to store enough power at your home to handle days when your power output is down or there’s no backup power available from your utility company. This guide covers the ins and outs of storing solar energy, including:

• How storing solar energy works
• Benefits of storing solar energy
• Lithium-ion vs. lead-acid batteries
• Cost vs. lifetime energy savings

How Storing Solar Energy Works

The most productive hours for solar power generation rarely match your peak energy usage hours. For example, you tend to start turning the lights on and more closely managing the indoor temperature when you get home from work in the evenings, which also coincides with the sun setting. The logistics of solar means you need a way to balance when you generate power with when you actually use that energy— which is where storage technologies come in.

There are many ways to potentially store power, though residential installations tend to focus on battery options. Most other installations are for larger power generation activities and companies. The Office of Energy Efficiency and Renewable Energy notes that battery and thermal are the current leaders in solar storage technology.

Benefits of Storing Solar Energy

While the benefits of storing solar energy are just as numerous as the benefits of generating a renewable power supply, let’s focus on some of the most meaningful benefits to most consumers.

Store Energy for Later Use

Since you don’t use a static amount of power, you need a way to adjust the amount of power available to you at different times of day. Since peak hours are typically in the afternoon or evening, solar storage gives you a way to hold on to the extra energy from mid-day for later use. It’s also important to have storage to address days when you don’t get as much energy. If you have a major storm system rolling through, stored energy can keep your house up and running until the next sunny day.

Send Unused Energy Back to the Grid for Credit on Your Bill

Savings on your utilities is often one of the biggest reasons residential customers install solar panels. But, it’s an even more attractive option when you can generate enough power to send a bill back to your power company. Net metering, a billing agreement between solar panel owners and utility companies, is common, and credits are worth a different rate than what you give to the grid. With solar storage and the right number of panels, you may generate enough power to more than supply your home. With power banked for the future, you can sell the excess and avoid the rising cost of electricity.

Prepared for Emergency Situations

Solar storage keeps your lights on, even when the energy grid is down. If a major storm knocks out the power in your area, a generator might run things for a few hours, but solar power with battery storage can keep your home running at mostly normal levels. No need to worry about tossing the contents of your fridge or enduring cold showers when all of your appliances keep running.

Off-Load Excess Solar Power

As with any appliance, too much power isn’t a good thing. If your solar panels produce more power than your home is using, there can be a backflow of energy. Too much electricity often translates into heat, which can build up in your solar panels, causing damage. Damage to your panels means they don’t last as long and start to lose optimal performance levels. To get the true value out of your solar panels, you need a way to get rid of that excess power safely and securely. This is where having a backup battery comes in handy. It will absorb any excess energy, which you can safely use at a later date.

Lithium-Ion Vs. Lead-Acid Batteries

Lithium ion and lead acid batteries both work through an electrochemical process that involves storing a charge and releasing electrons. The near identical process for both batteries means that materials used to make the batteries plays the biggest role in performance.

In general, we recommend lithium ion batteries for use as solar storage, such as Tesla’s Powerwall battery. Lithium ion batteries have a larger capacity and let you access more stored power per charge. Plus, these batteries are the more efficient option.

Lead acid batteries are a whole lot cheaper to install (almost 10 times less, in fact). However, because they last so much longer, and with much higher efficiency, lithium ion batteries win the cost race in the end.

Cost Vs. Lifetime Energy Savings

Installing solar storage can be pricey, with lithium ion storage averaging between $5,000 up to $15,000+, depending on the number of batteries and the capacity needed. The U.S. Department of Energy estimates that battery storage is likely to be the most costly part of switching to solar with an initial cost of between $80 to $200 per kilowatt hour.

Even with the high upfront cost of installing solar panels and storage units, most residential users see a lifetime savings on energy costs. In fact, solar installations typically pay for themselves within the first 5 years, and modern panels can last for 30 years, giving you a clear value proposition.