Skip to content


Home » Not yet,Tesla. Not yet.

Not yet,Tesla. Not yet.

  • by

Not yet,Tesla. Not yet.

The industry is buzzing with Elon Musk’s high hopes of putting a battery in every home and solar on every roof. The Tesla Powerwall is poised to reduce grid dependence and promote more self consumption- but in my very humble opinion it’s not there yet. After watching Elon’s unveiling video a few weeks ago and reading the pros and cons of this new venture, it only reemphasized the point that SMA already has products to handle his vision.

Let’s take a look at some of the limitations of the Powerwall:

The 7kWh model “doesn’t make financial sense” and SolarCity will not be offering this model to its residential customers.
The 10kWh model can be used for battery backup, but it is only rated for a continuous output of 2kWh.
A single 10kWh Tesla battery costs $7140, however that doesn’t include all the other “stuff” required for a battery backup.
To replace a 16kWh $3700 generator, the customer would need to lease eight stacked Tesla batteries for $45,000 for 9 years.
The Powerwall doesn’t have the surge capacity to handle large loads.
The alternative (available right now) are two SMA products. The first would be an AC coupled system using a Sunny Boy and a Sunny Island for a complete 16kWh (333 amp hours) grid tied battery backup system that will cost less than (or the same as) just the Tesla battery bank. Although it isn’t as sexy looking as multiple Powerwalls stacked together, a single Sunny can handle the start-up of a 2.5HP well pump with 180A for 90 ms. Take that Tesla! Combining multiple Sunny Islands could take someone off the grid permanently.

Of course, a more economical solution would be the Sunny Boy with Secure Power Supply. Included into the price, this inverter family can produce 1500W of power when the grid is down, when the sun is shining and WITHOUT the need for batteries. This is enough to power phones, smart devices, lights, small heaters, a small fridge to keep Grandma’s insulin cold, a 12V battery charger for portable power for nighttime loads, a baby bottle warmer- or possibly even a larger fridge depending on the make and model.

Preemptively battling off the hater comments, I wholeheartedly agree that the Powerwall has potential. Like the Apple products, there will be early adopters (like me) who will stand in line to buy the latest and greatest thing which will help improve the products over time. But, SMA has already taken the time to develop products that have been battle tested over the last 30 years that also come with a more reasonable price tag.

Notice the inverter hanging on the wall?



Skip to content