Is Solar Power for Data Centers a Bad Idea?

Facebook has built a large solar array next to its new data center in Prineville, Oregon.

Solar power has become the hot new accessory for major data centers. In the past several years, arrays of photovoltaic solar panels have been announced for data centers from Apple, Facebook, Cisco and Emerson Network Power.

But do these solar arrays make sense, given the current economics of solar energy and the volume of power required to support a modern data center? James Hamilton of Amazon Web Services, who often presents on data center economics at industry conferences, challenges the wisdom of solar in a new blog post.

“I love solar power, but in reflecting carefully on a couple of high profile data center deployments of solar power, I’m really developing serious reservations that this is the path to reducing data center environmental impact,” Hamilton writes. “I just can’t make the math work and find myself wondering if these large solar farms are really somewhere between a bad idea and pure marketing, where the environmental impact is purely optical.”

Solar power hasn’t been widely used in data centers because it takes a very large installation of photovoltaic (PV) solar panels to produce even a fraction of the energy required by most data centers. Some arrays, like the one at Facebook’s Oregon facility, provide power for office space rather than the servers n the data center itself. Looking at solar output data at different geographies, Hamilton says the output of these arrays – even Apple’s proposed 20 megawatt facility in North Carolina – just doesn’t add up.

While praising Facebook for its efficiency, Hamilton says the array in Prineville is “very close to purely marketing expense.” So what are the economics of solar from a marketing perspective? It’s probably not an accident that the flurry of on-site solar arrays appeared after Facebook took a public relations beating from Greenpeace, which launched a high-profile “Unfriend Dirty Coal” campaign to protest the low volume of renewables in the power sourcing  for the Facebook facility in Prineville.

Greenpeace Not Impressed

But seeking to appease Greenpeace with solar panels seems a foolhardy undertaking, as evidenced by the environmental group’s  reaction to Apple’s announcement of its 20-megawatt solar array. Rather than praise Apple for its commitment to on-site solar for its data center, Greenpeace  used the release of the “new iPad” to bash the company for relying upon coal-sourced energy from the local utility.

“Apple could apply the innovative spirit so evident in its latest iPad to its iCloud by powering it with renewable energy like wind and solar,” said Greenpeace Senior Policy Analyst Gary Cook. “Or, it could continue to lag behind the rest of the industry by sticking with coal, a 19th-century technology that poisons communities and the climate.”

Like Hamilton, Cook argues that the solar array is inconsequential given the overall energy used by Apple. “While Apple has been more than happy to draw the media’s attention to how large the solar farm is, it has kept its lips stapled firmly shut when it comes to just how much coal will still be required to power the cloud,” Cook writes in Greenpeace’s response to the Apple solar announcement.

So if the economics don’t work, and Greenpeace isn’t impressed, what’s the future for solar in the data center? When it comes to renewables at data center scale, hydro power remains the best option.

For more, see Hamilton’s blog post and our special report on data centers and renewable energy.

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About the Author

Rich Miller is the founder and editor at large of Data Center Knowledge, and has been reporting on the data center sector since 2000. He has tracked the growing impact of high-density computing on the power and cooling of data centers, and the resulting push for improved energy efficiency in these facilities.

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  1. It will be interesting to keep an eye on. Are these steps in the right direction, or merely marketing ploys to distract and appease. Possibly both (even if accidentally). Apple has already begun construction on it's solar farm here in North Carolina. We recently went to the skies to video and verify. But, I suppose the question remains: Is something better than nothing? Or, shoud something simply be something else?

  2. Dan Barry

    Electricity "wastes" over distance. Producing electricity onsite, and with significant tax savings from governments state and federal is at least 2 wins. If the heat gain of the building from the environment is a factor, shade is one of the best ROI's available in a sunny area. Ask a real estate agent about trees. If the construction is new, the racking should be simple and not involve shutting down the facility. IF the data center improves in efficiency with less power hungry servers, its still a gain. Green cred is a plus but it goes in and out of fashion. If you have not seen it change at least twice, you are very young.

  3. What about green root, literally? Wouldn't they save a lot more if the roof were insulated with a planted roof?

  4. RS

    The panel arrays are religious icons. Their purpose is to demonstrate the green piety of the company, not to generate meaningful power or save money.

  5. Brian james

    "not to generate meaningful power"... Sorry but even at the size of Apple NC data center 20 megawatts pulling from the sun rather than the local power grid seems a decent amount of power. Also seems they are possibly building a 5-megawatt biogas-powered fuel cell system there too. So possibly 25 megawatts in all. Even if you take Greenpeace's super high 100megawatt estimated power usage needs, that would be 1/4 from two greener than coal sources. Seems like a good start to me. Anyone commenting here use much less off-set 25 megawatts of data center power on their own projects?

  6. Mike Jump

    Something else to consider, the North American grid is aging and under stress. 20mW of peak shaving on site generation has to be a benefit. Perhaps a large storage battery should be coupled with this system to aid frequency regulation and grid stability when a cloud shadows the array.

  7. Phil

    One factor that might help make Apple's array economically viable is reduction of utility demand charges. Residential users are used to paying just a certain amount per kilowatt-hour, but businesses pay a somewhat lower rate per kilowatt-hour plus a "demand charge" based on the peak kilowatts they draw from the utility, sometimes during a defined period of the day. By erecting a large solar array and connecting it directly to their loads (i.e., the data center and solar array share the same electric meter) the solar array offsets the power used by the data center and therefore the demand from the utility. In some cases these demand charges can be quite large, so it might well make economic sense for Apple to do what it's doing. I don't understand how Greenpeace can complain; 20 MW is certainly better than nothing, They should go protest data centers that have no renewable energy at all, and that's the vast majority.

  8. I would think that even part of the data centers being powered by solar energy would be a plus all the way around.

  9. Lennie

    The only Solar Power I believe to really work at large installations is Molten salt solar power plants, because they can store energy. But no datacenter that I know of has tried that.