What is the Tesla Powerwall? The Tesla Powerwall is a lithium-ion battery that is rechargeable and designed explicitly for the home energy storage market. It can be used as a backup power source, power load shifting and as a battery for storing solar power generated during the day for night time use.
YouTube: Elon Musk Debuts the Tesla Powerwall
Lithium-ion batteries are nothing new and were first researched in the early 1970's, since then the development of smaller and more efficient Li-on batteries has continued with most small electronic devices such as mobile phones and laptop computers using the technology. Unlike traditional led acid batteries lithium-ion units need no maintenance, can be discharged to a greater degree and can be recharged in some cases up to 10,000 times.
The Tesla Powerwall has a capacity of 7kWh and is designed for a daily discharge-recharge cycle, and multiple units can be installed together to increase storage and power output capacity. Each unit is liquid cooled with a type of chemical coolant.
The daily cycle 6.4kWh battery uses nickel-manganese-cobalt chemistry with a life of up to 5,000 charge cycles before the warranty runs out. The Tesla Powerwall has a 92.5% round-trip efficiency when charged or discharged by a 400–450 V system at 2 kW with a temperature of 25 degrees, and when the product is brand new. Age of the product, temperatures above or below 25 degrees Celsius, and charge rates or discharge rates above 2 kW would lower this efficiency number, decreasing the system performance. Tesla also has a 10kWh weekly cycle version intended for backup applications, but it is the 7kWh version you will see in most home installations.
The Powerwall also has a built-in includes a DC-to-DC converter to sit between a home's existing solar panels and the home's existing DC to AC inverter. If the current inverter is not storage-ready, one must be purchased.
Tesla Powerwall Specifications:
- Voltage - 350–450 V DC
- Current - 9.5 A
- Power - 3.3 kW
- Energy - 6.4 kWh
- Operating temp - −20 to 43 °C
- Weight - 97 kg
- Dimensions (H x W x D) - 130 cm × 86 cm × 18 cm
The diagram below shows a possible Tesla Powerwall setup for a grid connect solar power system.
How much does Tesla Powerwall cost?
For homes that already have solar panels installed, Powerwall plus a compatible power inverter will set you back around $12,000.
Can I go completely off-grid with Powerwall?
This is not an easy question to answer as we all have different power needs, even so, a 7kWh battery will not be enough to supply most homes. Extra Powerwalls can be installed to increase capacity.
How will Powerwall effect the grid?
These days many power consumers are concerned about the constantly changing price of electricity, and the effect of coal-fired power on the environment.
Many homeowners would prefer to go off-grid and generate their power if they had technology that was reliable as an all year round power supply.
With the cost of solar panels continuing to fall along with battery storage systems, homegrown power supplies are fast becoming more viable.
What is the payback time for the Powerwall?
Every home has different power needs, so it's not easy to calculate payback times. If you use all the power you generate from your solar panels without exporting any back to the grid and then having to repurchase it the payback time will be less.
A good solar power system payback calculator can be found here Solar Payback Calculator - SoalrQuotes.com.au.