Admiration for Tesla’s new Powerwall battery

The sleek Powerwall battery.  Source: Tesla

The sleek Powerwall battery.
Source: Tesla

I’m going to stray outside the usual focus of my blog and take a look at the new battery that Tesla announced last night. Not because I have any additional insight or product ideas, but because I’m so impressed by Elon Musk’s ability to create products that people fall in love with because of functionality and gorgeous looks, yet are designed to benefit the environment as well as their owner.

The premise is that solar energy is at its most efficient midday, when the sun is strongest, yet electricity demand peaks in the morning and the evening hours. Tesla’s battery unit is designed to be charged by solar energy during the day and discharged (used) during the evening, nighttime and following morning. It’s a win-win: consumers with with a lower power bill and the  electric utility company wins with lower demand during the day.

Wired did the math (and physics) and estimated that the more expensive Powerwall, the 10 kWh model priced at $3,500, can power an average house, one that uses 2 kW of power, to get 5 hours of use from the battery. While the cost seems relatively low, potential buyers will also need to invest in solar panels capable of charging the battery and an AC-DC inverter. (Note: Elon Musk is the chairman of SolarCity, a provider of solar systems.)

In the big ecological picture, the Powerwall battery does something that has previously only been done on a much, much smaller scale: it stores electricity. On NPR this morning JB Straubel, Tesla’s co-founder and chief technology officer, mentioned that “it’s amazing the electric grid can work as well as it does with no storage…If there’s a surge in demand and you run an energy company, you have to fire up an extra power plant. It’s an entire market for energy transaction that has no inventory and no buffer. So every single thing is delivered instantaneously, just in time.”

What this means, added Straubel, is that there is enormous waste. Waste means that power plants are needed to create electricity that consumers may or may not use as well as building plants to meet that peak demand, not just average usage. For utilities and the environment, consumers using batteries powered by solar can help cut down this waste, lowering carbon emissions. In the short term, utilities benefit by balancing load on grid as consumers need less electricity during peak hours. As utility production is planned for peak hours, in the long term, utilities can avoid the cost of building additional large power plants outside the cities that need them.

A view over Tel Aviv rooftops. Note the proliferation of water tanks and solar panels on every building.

A view over Tel Aviv rooftops. Note the proliferation of water tanks and solar panels on every building.

Now, all this won’t happen overnight but it makes sense to use solar power in states like California that get sun almost every day a year. Saving energy for later use has been done on a smaller scale than the Powerwall in a much lower-tech way in Israel, for decades, with a solar water heating. In fact, building code required every apartment in every building, not just single-family homes, to have a system that included solar panels and a water tank. By using solar energy, Israelis don’t need to heat water at all during most of the year. The technology has become so commonplace that it is also cheap: a complete system costs about $750. Of course, it’s not as beautiful as the Tesla Powerwall and only covers one aspect of energy use, but I think it’s a testament to how cheap solar systems can become. In fact, looking at prices for solar panels in the US,  The average cost of solar panels has gone from $76.67/watt in 1977 to $4/watt in 2003 to $0.613/watt in 2013 and is expected to fall another 40% in the next two years.

Elon Musk has created a product that can benefit consumers, utilities and the environment by modifying a product he has already invested research and development effort in, car batteries. He’s taken a bold, first step to make solar energy more useful and more accessible. Much respect.


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