Figure 1. Is this installation a work of genius or political correctness?


Cloud computing, virtual machines, low PUE claims, being the greenest and most sustainable. Every enterprise and vendor claims to have squeezed the last watt out of operations just to lay claim to the title of being the most efficient operation in the world. So when driving down the highway the other day, I came across this installation (see the photo) and could not help but think: Was this an ingenious or absurd application of a solar installation for increased power efficiency and 24x7 use of solar panels?

Think about it. How ingenious is it to have a solar panel that is operational 24x7? Doesn’t the installation of a solar panel under a streetlight make the installation more efficient? Doesn’t the design of this installation allow the solar panel to produce more power? Is the additional power generated by the streetlight considered a green power source?


It’s absurd, say the purists. It’s ridiculous. Streetlights are installed to provide area lighting at night for safety and security. The installation of anything that interferes with those functions defeats or degrades the purpose for which the streetlight was intended. The solar panel blocks the light and casts shadows on the ground that could possibly obscure a pedestrian from view.

Furthermore, the deliberate installation of a solar panel below a streetlight for the specific intention to regenerate electricity is an efficiency application run amuck. If the streetlight has so much excess light (power) it would be far wiser to use less energy by installing a lower wattage light that more closely matched the lighting need. The power losses due to the multiple transformations of electricity to light and then back to electricity make the process terribly inefficient. Finally, this installation is anything but green. The nighttime electrons are all sourced from the utility and cannot be considered green power.


It’s ingenious, say the dreamers. Make every watt count, they say. This is ingenious. Streetlights are applied to deliver a specified minimum lighting level at the perimeter of their coverage areas that usually leaves a bright spot directly beneath them. The use of solar panels to capture a streetlight’s excess energy at these bright spots improves the existing installation by capturing otherwise excess lighting energy and transforming it into a useful form. Further, the installation of solar panels under streetlights allows the solar installation to function 24x7 vs. only when the sun shines, thus vastly expanding it’s lifetime production of carbon free energy.

Finally, this installation is totally green. The nighttime electrons are not sourced from the utility. The utility’s carbon-sourced electrons have been consumed and released by the streetlight. Any and all use of these free electrons is a direct reduction in the need for additional carbon-based electrons and are as such should be considered green.

These opposing arguments are part of challenge we face every day with greater complexity within our data centers. So what is your point of view?

Reality Check: Solar panels are not your pocket calculator photocell. One should not expect to get any usable power from a solar panel under a streetlight.

In the 1970s and 80s, when energy management industry was in its infancy, electronic motor controllers would rotate through the air handlers in a facility, cycling them on/off based on a defined time sequence regardless of what the air conditioning and ventilation needs were. Imagine the chaos in a data center if the CRACs routinely cycled on/off to save power? With cooling in most data centers already strained, who would allow some energy zealot to install a time-based cycling program? Although the data center cycling idea is, on the surface absurd, the genius had to wait until we had CFD air-stream mapping to understand the effects of cycling and VSDs to save the same energy without the negative effects of completely turning AC units off.

Similarly, many of you have disabled the sleep mode on your laptops despite company directives to the contrary. The sleep mode is in direct conflict with your work needs, and it diminishes your ability to perform your intended work.

Those of you who have not disabled the sleep mode on your laptop are saving energy during those long conference calls, lunch breaks, and all night long when you get distracted and go home without turning the laptop off. This effectively is extending the useful calendar life of your laptop.

So, I ask again are these ideas absurd or genius?

Perhaps operating a solar panel 24x7 under a street lamp is absurd today, but technology is forever changing. We need to embrace new ideas and move them to solutions. We found a way to dynamically match data center ac capacity with real loads. With smart phones and new instant on devices is there really an issue with our laptops going to sleep? We once thought it absurd to put a server to sleep, yet we are now close to having programs that are able to control energy at the component level without degradation of performance.

Ultimately, we should not be quick to dismiss new ideas as absurd. In the end, the genius is finding the solutions that make the new ideas work.