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Five weeks after Hurricane Maria crippled Puerto Rico's electrical power grid, and just three weeks after Puerto Rico governor Ricardo Rossello reached out to Tesla founder Elon Musk for help on Twitter, Tesla has delivered its first big solar-plus-storage installation on Puerto Rico, equipping a children's hospital with solar panel arrays and batteries that make the hospital self-sufficient for electrical power. NPR had this online report on Wednesday, October 25 (see: "Tesla Turns Power Back On At Children's Hospital In Puerto Rico," by Bill Chappell). Reported NPR: "The hospital's new system allows it to generate all the energy it needs, according to El Nuevo Dia. The facility has 35 permanent residents with chronic conditions; it also offers services to some 3,000 young patients, the newspaper says."

"The news of restoring permanent power at the hospital comes as millions of people in Puerto Rico continue to rely on generators for electricity," NPR reported. "As of Wednesday morning, the Electric Power Authority reported that its power service was at 25 percent."

Tesla has company, reported Grist (see: "Tesla’s solar vision gets its first big test in Puerto Rico," by Amelia Urry). "Tesla is only the most prominent company to bypass the conventional avenues of rebuilding to install renewable power and batteries," Grist noted. "Other companies and nonprofits have been marshalling resources to fill the void left by federal relief efforts. German renewable energy outfit Sonnen has pledged to build microgrids in priority areas, working with local partner Pura Energia to install donated batteries to power first aid and community centers. Another group, Resilient Power Puerto Rico, is distributing solar generators to remote communities, where they can serve as hubs for immediate necessities like charging phones and filtering water."

Commentary: Puerto Rico's experience is interesting in light of the ongoing policy debate on the mainland about the challenge solar energy poses for the electrical grid. Electricity has traditionally been supplied by publicly licensed utilities that have monopoly market share in their service areas, and in recent years, electric utilities have been lobbying hard at all levels of government to reduce or eliminate rate structures that incentivize the deployment of photovoltaics. The utilities note two primary drawbacks of photovoltaics: One, the intermittent nature of solar-generated energy, and the fact that it doesn't work at night, challenge grid operators tasked with the duty to supply continuous and consistent power throughout the 24-hour day; and two, rate structures that let local solar producers sell power back onto the grid at retail rates allow panel owners to unshoulder some of the cost of building and maintaining the grid.

In Puerto Rico, where the grid has been notoriously unreliable, and where it has just been shown to be incapable of rebounding in a timely way from natural disaster, the grid's credibility may already be too weak to sustain those arguments. But more to the point, there's a big practical difference between simple solar projects and "solar plus storage" projects of the type Tesla is bringing to Puerto Rico. When solar panels are paired with enough batteries, they can flip the script on the utility problem: solar panels alone may be a liability to the grid, but solar panels combined with batteries and tied to the utility can be a huge asset to the power grid. Batteries can be made "dispatchable" — that is, coordinated with other power sources and controlled by the central utility system to absorb excess power in times of low demand and release power in times of high demand. Solar-plus-storage plants also place power generation closer to its point of use, reducing the need for expensive and vulnerable transmission lines. In principle, micro-grids scattered about Puerto Rico, or about any power grid service area, could reduce the cost of building and operating the grid itself, and make the grid easier to manage rather than harder. And there's more: batteries can even improve "power quality," helping to maintain a clean, static-free voltage cycle that helps machinery and electronic devices run better and more smoothly.

Tesla has competition in the solar-plus-storage field from several big rivals. But unlike the competition, Tesla's also a car company — which adds to the synergy. The batteries in a Tesla motor vehicle could, in principle, be "dispatchable" — able to store surplus grid power and help grid operators match generation to loads. At some point, a world full of garages with solar roofs and Teslas parked inside could change the face of the power grid.

Something to think about, next time a Tesla blows your doors off on the interstate.