Solar batteries, also referred to as energy storage systems, provide a range of benefits for certain situations. However, for the average grid-tied customer, solar batteries probably aren’t necessary and provide peace of mind more than anything. There tends to be a lot of misconceptions around solar batteries, so we’re hoping to provide a little clarity.

How do they work?

Here’s the short version on how solar batteries work; during full sun exposure, Photovoltaic (PV) panels create electricity and charge a battery connected to the system.

 The longer version; when installing a solar battery as part of your grid-tied solar system, you can store excess energy instead of sending it back to the power grid. If your panels are producing more electricity than you need, this energy can go back into charging your battery. When your solar panels aren’t producing electricity, like at night, you can draw from the stored energy when you need it. The electricity is sent back to the grid only when your battery is full or draws from the grid only when the battery is low.

Do all solar systems have batteries? Do they need to? 

Not all solar systems have batteries and if they are grid-tied, they likely don’t need to. Keeping a solar battery backup is advantageous in particular situations, but it is not necessary for everyone.

So what is the number one situation that might warrant an energy storage investment? If the grid suffers an outage, having solar batteries will provide a safety net so you can keep the lights on and your phone charged. A grid outage is very rare, but there is definitely value to having peace of mind.

Thinking about this in the big picture; in our area the amount of power outages are limited to severe weather, squirrel incidents and accidents with vehicles damaging power lines. The actual time without power averaged throughout the year is well under 1% of the time. Most cases the the outages are under an hour or less. We’re very fortunate to have a grid that is reliable and monitored 24/7. This isn’t Texas, right?

How much do they cost?

Commercial Lithium-ion (Li-ion) batteries, the same type that powers your phone, laptop, and electric vehicles have been with us for approximately 30-plus years, but the prices haven’t seen the same significant drop as PV panels have in the last two decades.

Average up front pricing for a residential battery back-up system can range between $12k to over $24k after incentives. Some manufactures also require that the storage system be part of their package -their panels, inverters, etc. There are some incentives and rebates, but the truth is that a battery backup system isn’t going to pay for itself as quickly as your solar panels.

If you go with a $12k battery investment to start you should be able to have a reliable backup able to keep the lights on and the refrigerator running when the power goes out. So your milk wont spoil, but adding conveniences like an electric stove, hot water heater, an air conditioner, or keeping your electric vehicle fully charged is going to drain that 10kWh battery very quick (and only fill 10% of your tank). Adding a series of batteries gets you more power for a longer period of time but the price currently outweighs the benefit significantly.

How long do they last?

Consider the cost of a small portable gas or propane generator like contractor’s use, which is usually under $2k, lasts 5 hands, and needs professional service annually. The average life span on batteries designed for residential use is 10-15 years and models like the Tesla Powerwall, LG Chem, and SonnenCore are only under warranty for 10 years or less. At Renovus, we install Sonnencore batteries which are designed to last 20 years.

Can I add batteries to my existing solar system?

As the market changes and technology advances, you may decide that it would be beneficial to add batteries into your existing system. In most cases, adding a battery to an existing grid-tied solar system is possible, however, the level of difficulty is dependent on whether or not your system was designed with the intention to do so. We’d be happy to sit down with you and discuss whether or not adding batteries is possible and makes sense based on your situation.

The future is looking bright. As technology progresses and prices drop, solar batteries may eventually replace back-up generators all together. The energy landscape is constantly changing and as more consumers demand green energy solutions, new innovations arise. We’d be happy to develop a custom solution and provide a quote if you’re ready. Our engineers love new challenges and have probably done the math already.