Tesla's Powerwall: Prepare for the Storm

By Jonathon Jeckell

In the ever-evolving saga of Tesla innovation, let’s take a glimpse at the ‘big picture’ efforts in play… because as we have come to expect from Musk, there’s always a hidden card up his sleeve and in this case it impacts the broader issue of renewable energy resourcing. The carmaker recently added a feature called ‘Storm Watch’ to their Powerwall home energy storage batteries that can automatically anticipate approaching storms and maintain a high charge to prepare for them. 

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For those who aren’t in the burgeoning Tesla-class, here’s some insight in how your neighbor’s electricity-sucking sedan can impact your place in the grid… For starters, Tesla Powerwalls and any other storage system that comes to market will be good for everyone on the grid, whether or not that grid has any renewable energy on it or not.  The Powerwall was originally developed to help homeowners store solar energy they produced during the day to continue powering their home at night when solar can no longer generate electricity.  Some people and businesses installed them just to provide backup power in case the power goes out.  In states that have net metering, the Tesla Powerwall can even charge when electricity is much cheaper (usually at night, when demand is very low) and either use the energy during the day (when demand is high and spot electricity prices are also high) or sell it back to the grid.  Users with solar generation can do both by making electricity during the day and buying it from the grid at night.

This approach makes the grid much more stable when considering sources of electrical power spread across an area reduces the strain on overloaded segments of the grid.  Powerwall owners that sell their electricity back to the grid during peak demand can supply nearby parts of the grid rather than having distant power-stations pump it across the entire network.  Hot days when everyone cranks up the air conditioning are an example of when segments of the grid can become overloaded and unstable.  When a segment fails, those failures can cascade to others that try to fill the demand, leading to large rolling blackouts.  Grid operators have developed much better technology and processes to isolate failures before they can cascade, but it can still cause large portions of users to lose power.

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How does this impact my power, you ask? Heatwaves often precede large storms, which stress the grid, sometimes to the breaking point, before the storm winds and lightning take their toll.  So if the Powerwall Storm Watch feature merely holds on to the power it collected while the grid was not stressed or from the owners own solar power, it does little to help the grid (aside from reducing the load by one household). But, for instance, if Storm Watch draws power from the grid to charge up before a storm hits, it could make the stress on the grid much, much worse.  If homes across an area are already straining the power grid running air conditioning, adding significant numbers of high capacity batteries on top of that would obviously be catastrophic (this also applies to electric cars returning home from work).

Grid storage is crucially needed and many grid operators are adding Tesla Powerpacks (larger versions of the Powerwall that can store 100 or 200 kWh of electricity) to help smooth out their power distribution from intermittent renewable sources (like wind or solar) without resorting to natural gas plants (that can quickly respond to surges in demand). But the power storage provided by the Powerwalls and other storage in private homes can help even more since they are even more dispersed.  Many people investing in solar power for their homes, who are often the same ones who purchase Powerwalls, often do so for idealistic reasons.  In a perfect scenario, Storm Watch will complete its charging before the grid gets stressed and at worst withholds power to remain charged rather than stressing the grid past the breaking point before the storm.  And perhaps utilities can develop ways to collaborate with Powerwall owners to help ease pressure on the grid without depleting their own stocks of stored electricity... Wouldn’t that be nice if everyone played nicely together? Perhaps wishful thinking, for now…  

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