Are Solar Batteries Worth It?
In theory they make perfect sense. “I’ll just store all the extra energy I’m producing myself, cut the cord with Rocky Mountain Power, and tell them to go soak their heads”.
Easy tiger. If only it was that easy.
The Best Battery on the Market
Let’s take a minute to walk through the realities of a battery backup. We’ll use the Tesla Powerwall 2.0 as our example (the most widely recognized solar backup battery on earth and currently the most cost-effective battery on the market and the best value for your money -- shill much?). This battery has a list price of $5,900 and has a power capacity of 14 kilowatt-hours of energy. Let’s break down this nerd-speak.
How Much Power Does a Solar Battery Get Me?
The average American household uses about 30 kilowatt-hours per day. Looking at the Tesla battery, this means one Tesla battery could power your home for approximately a half a day. To fulfill your dream of leaving the power-grid and becoming 100% self-sustained, you want at LEAST two days’ worth of backup power to cover cloudy days/snow days.
Some simple math would put your battery bill at $23,600. Oops…silly me, that total doesn’t include the cost of installation, permits, etc. All in, each Tesla battery adds approximately $8,000 to the cost of a residential solar system (or $32,000 for the two-day backup mentioned above). And for those keeping score, that is MORE than the entire cost of a typical residential solar system.
This leads me to the next question. “What about backup power for when the Grid goes down?” Let’s look at the numbers. Rocky Mountain Power’s grid was up and active 99.5% in 2017. This means the average customer lost power for 43.8 hours in 2017. The question you then need to ask yourself is “Does this downtime warrant an additional $8,000 price-tag on top of my solar purchase?” For a few it might. For the vast majority it won’t.
On a 20-year solar loan (most common form of purchase), one Tesla battery would add an additional $44 a month to your loan payment. As much as I hate the $5 a month “grid connection” fee Rocky Mountain Power charges solar customers, that’s a MUCH cheaper price to pay each month to be connected to a giant battery able to store all of my surplus power (to be clear they’re not storing my surplus, simply crediting me for the surplus).
Although the economics above paint a costly picture for storage, I am very encouraged when looking at the future of solar battery storage. The hardware prices will continue to shrink as the power rates continue to increase. At some point in the next 5 years those axes will cross and storage will begin to start making sense. Until then, take the first step and invest in a solar system for your home. Batteries not included.
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