There has been a lot of media around solar and battery storage in recent years. Tesla alone has launched a massive campaign around their energy storage platform “Powerwall.” Solar plus Storage has such a great ring to it and sounds like it’s the most logical thing to do when you have a PV System, grid-tied or otherwise. Storage is absolutely the future of the solar industry, but is it worth it right now?
To understand that question, you have to understand the need for batteries. In most of the Continental US (especially here on the East Coast,) batteries are used for one thing, backup power. In the event of a grid power outage, your battery system will kick on (almost instantaneously) and provide backup power to the circuits in your home. The great thing about this is that your solar system will ideally charge the battery in the daytime, seemingly giving your storage system an unlimited supply of energy.
Storage
Battery systems are so much more than just backup power. We call them storage for a reason. They have the ability to store power during the day and allow us to use that energy when the sun goes down, effectively allowing us to use solar day and night. This is great for commercial use because they have something called demand and peak charges (or time of use (TOU).) Having storage allows them to offset these charges effectively making storage a sound financial investment. However, residentially, other than some small areas here and there in the United States, we do not have these charges. So the financial benefit is not as apparent.
Backup Power
Utilizing batteries for backup power is great, but I think more people need to understand exactly how that works. When most people think of backup power, they think of a generator. Generators are great because they supply what seems like an endless amount of power to the home (As long as the fuel is there.) Batteries are different in that they have a finite amount of power they can supply until the power supply is replenished.
I like to compare these two visually with water. A generator that utilizes a fuel source like Natural Gas or gasoline, supplies power like a hose connected to a water spicket. Turn the valve on and the water keeps coming. You can fill as many buckets that you would like with that hose as long as the valve is turned on. However, a battery is like a tank of water. You can connect your hose to that tank, but eventually, you will run out of water. So you have to be strategic about how many buckets of water you are going to use. The more water you use, the quicker you will run out of water.
Cost
The reality is that batteries are expensive. Some of the major brands for batteries will have you believe that the cost to have a battery is less than $10,000. And that’s not entirely wrong if you get one of the smaller 14kWh Batteries and the installation is simple. What does that get you though? As mentioned above, a battery has a finite amount of energy to use. You can connect a 14kWh battery to your entire house, but don’t expect it to last long. Turn the AC on and all the lights, refrigeration… you would be lucky to get a few hours of backup power.
The reality is, to get a good amount of power to backup, on average, you will likely need 2-3 of those 10-14kWh batteries. And the installation is more often a little more complicated than the simple setup they initially quote you on. On average, the costs are between $20K – $30K for a backup battery system that will still only get you so much power.
So is it Worth it?
That depends… The reality is that most homeowners think they need their ENTIRE house covered in the event of an outage. Most outages last less than a few hours. There have been stand out events like Hurricane Sandy and some other storms that left us all without power for days. Besides those rare events, we typically only see short power outages. Because of that, the actual need to cover the entire house is unnecessary. We actually only need the refrigerator, maybe a sump pump or well pump, and some general lighting to get us through an outage. Most heat is run by a gas furnace, and we can likely go without Air Conditioning (unless you have a medical condition) for a short period of time. If you have electric heat or hot water… I can tell you now that battery backup is not for you. That type of inductive electricity uses that storage up QUICK.
In a scenario where you only need to backup the essentials, a battery backup system is not bad. Especially considering what else the battery can do with TOU. $10K-$15K is understandable. However, if you want to cover your AC, electric oven, every light in your house, and more… then a battery backup system may not be the right choice. The cost of that compared to a generator that can cover all of that is huge. A 22kW Generac Generator, completely installed, can cost up to $15,000. Whereas for the same amount of coverage, your battery system may run you North of $25,000. There is also the environmental impact of all of this. If you are someone that supports climate change, then using fossil fuels to back up your home may not be ideal and the extra cost to help save the planet may be more important.
Overall the cost of batteries right now is hard to compare to a generator. However, as time goes on, the technology gets better and less expensive. More and more states are putting incentives in as well which help with the economics. Batteries are definitely the future of solar and how we power our homes. When will that future happen? Your guess is as good as mine.
Interested in a battery backup solution for your home?