The Tesla Powerwall System is a unique energy storage system focused on function, cost effectiveness, and a sleek, compact design.
Tesla Motors was founded in 2003. The company’s energy storage division, Tesla Energy, was announced in April, 2015. With the help of cost reductions due to economies of scale possible due to the company’s massive Gigafactory, major growth for their systems at the residential, commercial, and utility scale is expected.
As of 2017, The Powerwall is now a 14 kWh energy storage system. This new battery system effectively doubles the energy storage of the previous one, with approximately the same form-factor. Another major upgrade includes the key feature of a built-in inverter. The system can produce a peak power rating of 7 kW with 5 kW available for continuous power usage. It can be floor or wall-mounted to either outside or inside locations. The physical dimensions are 44″ x 29″ x 5.5″ with a total system weight of 264.4 lbs.
Other key features include –
- Advanced lithium-ion (nickel-cobalt-aluminum) chemistry – known for long life and safety.
- Liquid Cooled – Tesla’s advanced liquid cooling system ensures the system’s reliability and effectiveness.
- Scalable – as many as 9 Powerwalls can be used in series for additional storage requirements.
- Efficiency – a respectable 90 percent round-trip DC efficiency with a Depth of Discharge of 100 percent.
- Durable Design – resistant to dust and water making it suitable for both indoor and outdoor installations.
- Supported Applications – Solar self-consumption, time of use load shifting, and backup and off grid applications.
- Always Connected – Get weather related alerts as well as solar usage in real-time.
- Warranty – the system is warrantied to 10 years.
- Certifications – IEC and UL certified.
The Powerwall currently sells for $7,800 which does not include installation costs. The Tesla website suggests that installation can add quite a bit more to the product cost (We’ll assume less in the example below.)
So how does these figures breakdown to a cost per kilowatt-hour figure? Well, let’s do some rough “back of the napkin” math.
Here are the assumptions –
- 1. A savvy homeowner can find a certified electrician to do the job for $500. This brings the total cost to $8,300. (There may be additional permit fees, taxes, or connection charges as well).
- 2. This 10 year warrantied system lasts for at least 15 years.
- 3. The system gets nearly full usage everyday (13 kWh).
The total number of kilowatt hours provided is the estimated number of useful years multiplied by the number of days in a year and the daily usage amount – 15*365*13=71,175 kWh.
To arrive at the cost per kilowatt hour we divide the total cost by the number of kilowatt hours in its expected lifetime – $8,300/71,175 kWh = $0.12 kWh.
Twelve cents per kilowatt hour coupled with the cost of solar which is about six cents per kilowatt hour means that the cost for solar plus storage is $0.18 kWh. This is less expensive than conventional energy in a few major American cities. As battery costs continue to fall, solar plus battery storage will continue to make financial sense to more and more American homeowners.
Tesla began taking reservations for the first Powerwall in 2015. Since then, the company has developed a newer Powerwall with the specifications listed above. As of half way through 2019, supplies of Powerwalls are still limited due to battery cells being primarily used for the company’s vehicles.
The Tesla Powerwall can be considered a cutting edge development in the home energy storage market. The system offers much value in terms of it’s compact size, attractive design, and competitive pricing. The company plans on becoming a large part of the quickly transforming energy industry. Therefore, future improvements in both technology and price competitiveness can be expected.