nstalling a solar system can cost a lot, so many homeowners doubt whether they need to add solar storage, increasing the burden of the initial investment. To make a sound decision on whether or not to go for a PV system including both solar and storage, you should take a closer look at how it works and carefully consider all the fors and againsts of solar energy storage. We've put together a handy guide to help you with that.
How to store solar energy?
To begin, let's go over the basics and see what solar panel storage actually is and how it is used. Solar panel systems, as you probably know, generate electricity only when the sun is shining. However, we need electricity in the evenings just as much, if not more, than during the daytime. Solar energy storage became the cure to this dilemma, as it allows using energy generated by a solar system around the clock.
Solar systems tend to overproduce during sunny hours, meaning you will have some unused power. You probably wouldn't want this energy to end up being wasted, so you have two options: send it to the grid or store it within a solar storage system. The first one might work for many solar owners, but it has some limitations. For one thing, a solar system has to be connected to the grid, which is not always the case. And for another thing, you need to have a net meeting policy in your area. Otherwise, you will be selling energy to the utility at a loss.
Solar storage, on the other hand, is an across-the-board solution for those who want permanent access to electricity. It provides off-grid solar owners with 24-hour energy and gives grid-tied homes access to it without the need to rely on the electric grid. Now let’s break down the pros and cons of solar and storage PV systems.
Advantages of solar storage
Provides a backup source of electricity in case of a blackout
A solar and storage system is an excellent option if your area is regularly affected by power cuts. Not all solar shoppers know that a solar energy system won’t work during power outages from the grid, as solar modules stop generating energy to protect utility workers from electric shocks while repairing the lines. But if your solar system is paired with solar electricity storage, you will be immune from blackouts and enjoy a stable energy supply even when the lights in your neighborhood go out.
Helps make the most of time-of-use tariffs
Time-of-use energy pricing is designed to encourage homeowners to use more electricity during off-peak hours by offering lower rates when demand is at its lowest. As a result, those who need energy almost only during periods of peak demand will inevitably have higher utility bills. A solar storage system helps you save money by keeping solar energy for later and using it during peak evening hours without pulling expensive power from the grid.
Further reduces reliance on fossil fuels
Most of the installed solar systems so far are grid-tied, and many solar owners still draw energy from the grid regularly. This reliance on the grid slows down the transition from fossil fuels, but solar storage is a key to this problem. With a solar and storage system, you will become fully independent from the grid and make your home energy consumption totally renewable.
Disadvantages of solar storage
Requires large upfront expenses
High cost remains the biggest hurdle for customers who want to install a solar energy storage system. Solar storage often costs no less than panels, making the entire PV system’s price tag too steep. Depending on the size and battery chemistry, solar electricity storage can cost anywhere from $2,000 to $15,000, but most of them cost $8,500-$10,000.
Increases maintenance cost
By adding solar storage, you will get another essential component in your solar system, which is not immune to failure and therefore requires regular maintenance. So installing both solar and storage systems means extra effort and higher maintenance costs.
Types of batteries for storing solar energy
This is the oldest, tried-and-tested battery chemistry for solar storage. Even though lead-acid batteries are far less popular today than lithium-ion, some homeowners still choose them for solar power storage. This battery type is characterized by a lower depth of discharge - about 50%. This means you can withdraw only 50% from solar storage relative to its total capacity. Lead-acid batteries also have a low energy density (25–35 Wh/kg), that is, the amount of energy they can store compared to their size. And one more drawback that makes these batteries not the best option for a solar storage system is shorter cycle life: they usually deliver 500-1000 cycles of charge and discharge and thus last only about five years on average.
As for the advantages, buying and installing solar power storage with lead-acid batteries will likely be considerably cheaper. And even though they are somewhat inferior in efficiency to lithium solar storage, they can be a fine choice for remote off-grid solar and storage systems that aren’t used very often, for example, in vacation homes.
Li-ion is the prevalent battery technology not only in the portable electronics market but also in the solar storage market. Li-ion batteries typically have 80- 95% depth of discharge, with some industry-leading solutions reaching 100%. Their energy density averages at 100-265 Wh/kg, and their cycle life is between 4000 and 8000 cycles, making them an excellent solution for solar power systems with battery storage.
But for all their benefits, li-ion solar storage batteries have some drawbacks, one being a higher propensity to overcharge and overheating. Therefore, they have to be adequately maintained and protected. These batteries are also quite expensive to manufacture, which makes lithium-based solar energy storage considerably costlier.