Tesla’s Powerwall, Part 1

If you don’t already know what the Tesla Powerwall is or does, you should read this post. I am going to explain why it’s awesome and why you should know about it today. I won’t be able to cover every detail in this single post, so standby for more information to come in future posts!

Tesla’s Powerwall is a lithium-Ion battery that works with solar to provide power to your home in the event of a grid outage (Example: Hurricane Irma).


Why is it cool? First, because it’s Tesla and Tesla is cool as hell these days, IMO. Second, it looks awesome, especially when compared to other solar and battery backup solutions in the past – golf cart batteries and ugly equipment. Third, it’s functional and totally works – 14 kWh’s of storage! Fourth, it’s extremely affordable – so much so, that it’s challenging the costs of every other battery storage solution on the market and setting a new standard.

Tesla, So Hot Right Now.

Obviously, Tesla is doing something right because everyone loves pretty much everything they do. The Powerwall is a part of the Tesla store that no one really visits (back corner). I think it’s because no one knows what this thing is or does! It’s a sleeping giant in the back corner, waiting to be appreciated!

“Powerwall integrates with solar to store excess energy generated during the day and makes it available when you need it, minimizing reliance on your utility.”

So, it’s a battery? That’s correct! A battery that is charged by solar power. This battery can be programmed to use the stored power every night, or wait on standby for a grid outage.

What can it power?

One Powerwall can hold up to 14kWh’s worth of power – but that means nothing to most people, so here is the breakdown of two important things you need to know about power.

Simple math: If you have a single 60 Watt light bulb that is switched-on for one hour, how many Watt hours do you have? 60 Watt-hours or 0.06 kWh’s. If you have (10) 60 Watt light bulbs on for one hour, that’s 600 Watt-hours or 0.6 kWh’s. Starting to get it?

To understand the Powerwall’s 14 kWh capacity, you have to consider your home’s “load” (the sum total of the Watts that each thing in your home is consuming from the moment you turn it on) and time (or the amount of time each “thing” is switched-on for). This is how kWh’s are calculated. The sum of all the things in your house that are on and for how long. Quiz: How long can you leave on the (10) 60 Watt light bulbs in the example above if you have (1) Powerwall? The answer is approximately 23 hours (0.6 kWh’s/ 14 kWh Powerwall capacity = 23.3 hrs).

The second important thing relates to your AC, which is what you care about the most during a hot, hurricane season day. “Can I power my AC?” The MOST common question. Answer: Yes and No. On one Powerwall, no. Definitely not. You will likely need at least two Powerwall to get your AC running. Remember the example above, AC units use a lot of power. Your AC will run a few thousand Watts when switched on – depending on the age of your AC unit. When turned on, an AC unit could drain your battery fairly quickly, so you have to manage your expectations. You could also just buy more battery capacity to solve that problem, it’s pretty much that simple.

The most important thing to remember is that everyone’s home and energy use are as different as the people that live in them. It’s completely up to you (the homeowner) to manage your energy and expectations when the power goes out. If you’re running on battery power only, it’s not a great idea to blast the AC, unless you know you have the extra battery capacity to do so. Solar and battery backup systems require a lot of planning and if you don’t work with an experienced/certified company, you might find yourself with less power than you thought when the grid goes down.

Stay tuned for the next post which will detail how solar and the Powerwall work together and how we determine the amount of Powerwall’s you need for your house.

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