Battery barrier to off-grid solar could fall

pic of solar panels in sunTwo big barriers stand in the way of everyday folks doing off-grid solar, meaning a completely independent solar system.

First, in order to qualify for what are often substantial rebates from utility companies, you have to install a grid-tied system. And the reality is that most people cannot afford to install a solar system without these utility rebates.

Second, the battery systems used for back-up on a off-grid solar system are expensive and inefficient.

As solar panel prices fall, the first barrier to a completely independent, off-grid solar system is not quite so daunting as it used to be, though, prices are still high enough that only the true economic elite can realistically afford to skip the utility rebate.

For example, without a rebate from Xcel Energy, the utility on Colorado’s Front Range, a 5.5 kW solar system costs about $31,000. With the current (as of Nov. 2009) $19,000 rebate from Xcel, that cost drops to a much more affordable $12,000.

While perhaps solar panel prices will have to fall further for the first barrier to off-grid solar to fall for most of us, there’s good news in terms of the second barrier to off-grid solar.

Storage system mimics photosynthesis
Daniel Nocera
, a researcher at MIT, is working on the development of a practical, inexpensive storage system that can also offer better energy density than conventionally used batteries.

Nocera has proposed a system that mimics photosynthesis in plants and uses solar energy to split water molecules into oxygen and hydrogen. While the oxygen generated during the process is released into the atmosphere, hydrogen is used to power fuel cells.

While the energy density of batteries is about 0.5MJ/kg, the energy density of liquid fuels is about 50MJ/kg.

Nocera’s approach of using the solar energy to produce fuel for a fuel cell could be the key to offering affordable personalized, off-the-grid solar energy in the not-too-distant future.

If you find complete electricity production and consumption independence attractive and you already have a solar system on your home, who knows, if Nocera’s innovations take off, you might soon be able to unplug from your utility and realize the satisfaction of complete electric autonomy.

(Some information for this article was drawn from