Why the solar-plus-battery revolution may be closer than you think

The Washington Post
June 24, 2015

By Chris Mooney

In late April, Tes­la Motors took a step toward upend­ing home ener­gy when it announced the Pow­er­wall, a bat­tery for homes that can pro­vide back­up pow­er, and that was paired with high­er capac­i­ty ver­sions for busi­ness­es and even pow­er com­pa­nies.

With­in about a week of the announce­ment, Bloomberg report­ed, the com­pa­ny had already pulled in $800 mil­lion worth of orders, with the vast major­i­ty of rev­enue not for indi­vid­ual home bat­ter­ies but rather for larg­er, com­pa­ny or util­i­ty scale appli­ca­tions called Pow­er­Packs. With num­bers like that, the ener­gy stor­age rev­o­lu­tion may already be here.

[Why Tesla’s announce­ment is such a big deal: The com­ing rev­o­lu­tion in ener­gy stor­age]

It’s not entire­ly clear yet how it will play out, though. In par­tic­u­lar, a big ques­tion mark con­cerns when a much tout­ed pair­ing of home ener­gy stor­age with rooftop solar pow­er — so that peo­ple can pow­er their homes at night with solar ener­gy gath­ered dur­ing the day, and need only min­i­mal amounts of pow­er from the grid — will become wide­ly avail­able, not to men­tion afford­able.

Some skep­tics have argued that it’s still very cost­ly to buy the Pow­er­wall — the cost is $3,500 for 10 kilo­watt-hours worth of ener­gy or $3,000 for 7 kilo­watt-hours — and have also object­ed that at least at first, it appears its chief usage will be sim­ply to pro­vide back­up pow­er dur­ing a pow­er out­age. Indeed, SolarCi­ty announced it was offer­ing the Pow­er­wall with home solar instal­la­tions for an added cost, but described it as a “bat­tery back­up ser­vice,” to replace “noisy, dirty fos­sil fuel gen­er­a­tors with zero-emis­sion stor­age tech­nol­o­gy.”

Nonethe­less, the solar plus bat­tery rev­o­lu­tion is com­ing in very much in the form many have envi­sioned, argued Nan­cy Pfund, the founder and man­ag­ing part­ner of DBL Investors, a San Fran­cis­co based ven­ture cap­i­tal firm that has invest­ed in Tes­la and SolarCi­ty, at a Tues­day Wash­ing­ton Post event enti­tled Amer­i­can Answers: Pow­er­ing Cities (I mod­er­at­ed the pan­el).

It is a rev­o­lu­tion,” Pfund said, adding that “it isn’t that far away.” When asked how much solar ener­gy capac­i­ty and bat­tery stor­age capac­i­ty peo­ple would need to ful­ly pow­er their homes with solar ener­gy at night and also charge their elec­tric vehi­cles overnight, she com­ment­ed, “remem­ber your cell­phone, how unfunc­tion­al and expen­sive and huge it was in those ear­ly days. Obvi­ous­ly there’s a cost curve that’s com­ing down…there’s a long wait­ing list of peo­ple want­i­ng to do this.”

To read the full arti­cle, vis­it The Wash­ing­ton Post.