I recently wrote about how off-grid, solar telecommunications towers are starting to use energy storage to extend the reach of communication networks. Grid-tied towers are starting to get in on distributed energy generation, too. One such tower in Shanghai recently added solar power and Aspen energy storage. What can solar batteries do for a telecom tower with reliable grid power? More than you might think.The primary job of the 45.6-kWh Aspen battery bank is backup power in case of grid outage. But about two-thirds of the bank’s capacity can also be used to play the energy arbitrage game.
Hybrid telecom tower in Hongqiao subdistrict of Shanghai and the Aspen solar battery bank at the Shanghai telecom tower
The power utility in Shanghai charges different rates for grid electricity throughout the day. When power’s cheap, the tower pulls electricity from the grid to power its loads and charge the batteries. When power’s pricey, the tower draws from the batteries instead of the grid--classic time-of-use optimization. The system also has a 5 kW solar array to squeeze in some free juice when the sun’s shining. Either way, the operators save money. Enough, apparently, to do this: