Powerwall Battery

What's Powerwall Battery

To put it simply, the Powerwall Battery is an energy storage device with a built-in rechargeable lithium battery pack, liquid cooling modules, inverters, and more. Charging during off-peak periods (such as early in the morning) and exporting power during peak periods , it plays a role of “peak clipping and valley filling”, and can also play an emergency role if the power grid fails. The Powerwall Battery is designed for home use and comes with a built-in battery of 7 to 13.5kWh. The commercial version of the Powerwall is called the Powerpack, which is a large device with a built-in battery of 100kWh. It is used in public places such as schools and hospitals.

A device similar to the Powerwall has been on the market for more than a decade or two. It is called the Uninterruptible Power Supply (UPS). Of course, the Powerwall battery has one advantage that UPS doesn’t have: it can be connected to a photovoltaic system that can be used to generate electricity during the day by sitting in the sun. The system comes from SolarCity, a company that specializes in home photovoltaic projects.

Besides peak clipping, what are the benefits

In addition to the “peak load, fill in the gap” and keep the electric appliances running, the Powerwall model can also make full use of the power batteries that have been retired from the trams.

Data show that the total installed capacity of new energy vehicle power batteries in China is as high as 57.35GWh, which reached 32.86GWh in 2018, with a year-on-year growth of 137%, accounting for 57.3% of the total installed capacity. If you take an eight-year life of a tram, a lot of power batteries will be retired around 2026.

Research institutes predict that by 2022 there will be 420,000 tons of decommissioned power batteries waiting to be disposed of.

The Powerwall model makes good use of decommissioned batteries. There are currently two main methods for recycling them: recycling (taking batteries apart to extract metals and materials) and cascade recycling (secondary or multiple recycling).

Similarly, in June this year, SAIC-GM-Wuling used retired batteries of Baojun E100 and E200 to build a megawatt large-scale power station, integrated photovoltaic and wind energy storage. The plant is used for the same purpose as the Powerwall, but with far more batteries. Since it was put into operation, the power station has effectively reduced the pressure on the Guangxi power grid during peak periods.

In addition to Wuling, it is known that Roewe R is also doing similar things at present. Currently, it is applied in Xichang City, Sichuan Province. The principle is almost the same as Powerwall Battery, so this paper will not repeat the introduction.

Of course, in addition to the stepped-use of decommissioning batteries, surplus electricity can also be sold to the grid. For example, Germany supports this, but this new business model is still in the exploratory stage in China.

Do we need Powerwall

Needs. The research on energy storage power station technology in China has started for many years. For example, as early as 2013, Shanghai hoped to reduce the peak-valley difference between day and night and level the load by utilizing battery energy storage, to improve the operation efficiency of the power grid.

If this kind of equipment is widely used, it will inevitably involve the problem of how to combine a large power grid and a micro–power grid. A large grid refers to a grid-based on centralized power generation (thermal, hydroelectric), which has the advantage of stable supply (e.g. voltage, frequency), but has the disadvantage of being difficult to cope with emergencies. Natural disasters, such as earthquakes and tsunamis, often destroy the power grid. If the micro–grid can supplement the large power grid, it will play a good emergency role.

A micro–grid is more like a small generation system than a large grid. Like the Powerwall Battery, it can operate independently but is also connected to a large grid, providing power to a load in an area if the large grid fails.

At present, Japan, who loves “hydrogen”, layout H2One hydrogen fuel cell system in the city , converting the energy of solar energy/time for easy storage of hydrogen. When the big grid fails, hydrogen is converted back into electricity and hot water is provided (a byproduct of hydrogen fuel cell power generation). And, of course, Japan has Ene-Farm, which makes every home a micro–grid.

China is still in the exploratory stage in the construction and operation of the microgrid, and relevant policies are not clear, so enterprises also lack a standard for technology iteration. However, the integration of a large power grid and the micro–power grid is inevitable in the future, just like private cars and public transportation, which jointly form our road transportation.

Why didn't Powerwall Battery catch on in China

The Powerwall Battery is popular in North America, where installed more than 100,000 Powerwalls by the first quarter of this year. If you have a big house, the Powerwall can save you a lot on your electric bills.

Powerpack is also popular in the commercial field. At present, Powerpack has been used to build energy storage systems in Tokyo, Osaka, Australia, and Europe. For example, Powerpack (7MWh) in Osaka is located next to Osaka Station, which can provide 30 minutes of running time for a train full of passengers in case of emergency. Enough to get it safely to the nearest station.

Then again, if the Powerwall Battery is so practical and so integral to future power networks, why isn’t it popular in China?

First of all, Powerwall is mainly sold to the eastern coastal provinces and the first and second-tier cities in southwest China. That is to say, most Powerwall owners live in buildings in big cities with stable power supply, so they naturally cannot and do not need to buy Powerwall Battery.

As for inland and western regions, although they have single-family big houses, few people buy electric cars due to climate and environment. How can anyone recharge their Powerwall Battery?