UK energy storage startup takes on Tesla Powerwall 2 in home battery market

Tesla Powerwall 2

Tesla, Inc.’s CEO Elon Musk has made his company’s mission to help the world to transition away from reliance on fossil fuels and toward the embrace of sustainable energy sources. Now a U.K. energy-storage startup called Powervault is now in competition with Tesla, Inc. to outfit homes with affordable backup battery power across the pond.

Why is solar power and storage the key to the world’s energy independence?

Solar photovoltaic (PV) power generation is at the heart of a transformation that will revolutionize the world’s electricity systems, letting consumers produce power for their own needs and feed surplus energy into the grid. Solar power is becoming ubiquitous: from large-scale utilities to micro-grids; from billion-dollar corporate HQs to rural rooftops; and from urban sprawl areas to small islands and isolated communities. We see solar next to airports, along highways, in fields, powering road signs, even at local small businesses like breweries.

Energy storage is an essential link needed to make intermittent solar energy reliable. Batteries installed inside homes can store excess energy produced by panels during peak hours of operation. When combined with smart meters and digital technologies, batteries can help utilities regulate the grid by providing power reserves which can be tapped and transmitted on demand.

As prices have dropped, solar PV generation uptake by households and local communities has increased dramatically. In 2015, around 30% of solar PV capacity installed worldwide involved systems of of less than 100 kW. This is gradually changing the face of power system ownership. Two companies — U.K.’s Powervault and the U.S. Tesla — are helping consumers to make the shift to solar installations combined with battery energy storage and a chance at energy independence.


Founded in 2012 with money from the U.K. government and private investors, Powervault has made a mission of reducing the cost of batteries in order to make them affordable to more homes. Powervault stores electricity in a home using either Lithium-ion Phosphate cells or Lead Acid batteries.

Powervault’s Lead Acid version is for customers who want a product with a low up-front cost and the prospect of upgrading to Lithium-ion technology when their Lead Acid batteries reach the end of their useful life in three to seven years. With Lithium-ion technology forecast to fall dramatically in cost over the next five years, customers can benefit from a low-cost Powervault using Lead Acid batteries now, then replace its batteries later. A Powervault lead battery that can store 3 kWh of power sells for 2,500 pounds ($3,117) a unit, or, about $1,039 for each kWh of electricity stored.  That price is about 12 percent cheaper than the $1,175/kWh average price in the industry, according to Bloomberg New Energy Finance.

Photo: Powervault

Powervault’s Lithium-ion Phosphate cells can store 2kWh – 6kWh of usable (AC) energy. Powervault’s Lithium-ion version is for customers who want a product with battery technology that is long-lasting and efficient; the Lithium-ion Phosphate cells are estimated to have a lifetime of eleven to thirteen years and can cycle more than once per day.

Depending on the battery technology and storage capacity a homeowner requires, the dimensions of the Powervault unit vary. The standard G200 unit accommodates all available battery capacities and technologies; the slim-line, G200-S unit , available starting in March, 2017 will only accommodate 2kWh or 4kWh of Lithium-ion Phosphate cells.

The company anticipates prices for Powervault’s batteries, which can cover about half an average British home’s daily power consumption, will be even cheaper going forward. Powervault is planning to expand internationally in the next few years with an initial focus on Europe, according to Powervault’s Managing Director Joe Warren, who said some units have already been sold in Spain. “We’ve been very careful to design them to be universally compatible. We want them to be easy to install and use everywhere in the world.”

Tesla Powerwall 2

Powerwall 2 stories are becoming commonplace, in which a consumer captures energy during daylight off-peak hours with SolarCity photovoltaic solar panels stored in a Powerwall home battery unit. When energy rates are higher during evening hours, the consumer powers the home with energy stored captured earlier in the day.

Artists rendition of a Red Founders Series Tesla Powerwall 2.0 hand signed by Elon Musk

Powerwall uses an internal inverter to convert DC energy to the AC energy required for a home or small business. A liquid thermal control system regulates Powerwall’s internal temperature to maximize battery performance in any climate. The most affordable home battery in terms of cost per kWh, the company argues that the Powerwall economically meets the daily energy needs of most homes. With usable capacity of 13.5 kWh, the Powerwall system has a 100% depth of discharge and 7kW peak / 5kW continuous power. Floor or wall mounted, indoor or outdoor, the Powerwall has a ten year warranty and is scalable up to nine Powerwalls. Its operating temperature ranges from -4° to 122°F / -20°C to 50°C. The system is certified to meet North American and international standards.

One 14 kWh Powerwall battery costs $5,500, with installation and supporting hardware adding $1,500, or a total estimate $7,000. U.S. installations are beginning in February, 2017, according to company data.

There’s no doubt Elon Musk sees solar as the future for electricity generation, just as he views electric cars as the future of transportation. “The primary means of energy generation is going to solar,” he said in 2015 prior to the merger with SolarCity, in which the issue of utility-based versus independent energy generation still seemed futuristic. “It will at least be a plurality, and probably be a slight majority in the long term.”

The forecast for solar in the U.K. and U.S.

The London-based Powervault company is targeting sales of 50,000 units a year by 2020, up from about 1,000 this year. Powervault is entering the home storage market just as Tesla is readying its Nevada-based Gigafactory for Model 3 production. Musk expects the plant will double the global production of lithium-ion batteries next year, so that, by 2018, the Gigafactory will reach full capacity and produce more lithium ion batteries annually than were produced worldwide in 2013.

Solar PV deployment at the consumer level alongside battery storage is putting pressure on network operators and the way national electricity systems are traditionally managed and governed. This is brought about by new developments in electricity storage, electric, vehicles and smart appliances. Solar PV already accounts for about 2% of global electricity in 2016, but could reach as much as 13% by 2030. In order for this to happen, solar PV capacity additions must double in 14 years, with Tesla leading the way and companies like Powervault joining the march.

Interested in solar? Get a solar cost estimate and find out how much a solar system would cost for your home or business.

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