Global Tower's new solar cell site makes a lot of sense since it reduces their opex expense at their California location by reducing generator fuel expenses by 45%. On the average it would probably be a poor use of their capital to invest in solar power throughout the nation, but in areas with grid systems, why not put in a larger PV system and gain income from excess power? Although it will not work in urban areas or where lease footprints are not able to be expanded, there are a lot of locations where this could be tried, especially where there are low power base stations. ROI calculations might not look terribly exciting now, but there may be some assistance in addition to tax credit incentives. There might also be the opportunity for CTIA or PCIA to lobby for grants to tower companies if they can identify that they can provide additional days of backup at a site in case of a catastrophic event or because they're taking the lead in reducing our carbon footprint throughout America - not in just a few locations. Plus, with tower top radios and other BTS advancements, we could see power requirements reduced by 50% in the near future, allowing each new engineering advancement to create an even higher residual income for the towercos.