Little Big Stuff: Inverters don't get no respect

By Lisa Margonelli

Inverters are the devices that convert AC power to DC. Solar panels are equipped with them so that the DC current can be integrated into household AC circuits. And homes that store energy from the grid in batteries (more on them in a second) also use inverters. But inverters are one of the tiny components of our energy system that have the potential to change the way we use energy-if only we stopped treating them like little insignificant commodities.

 Kevin Bullis over at MIT's Technology Review made a good catch in an NREL paper that found that poorly functioning inverters actually reduced the power output of one array of solar panels by 40 percent by drawing power at night. (And that power can be scarce with panels to begin with.) And furthermore, if no one remembered to manually reset the inverters, the panels didn't produce power half the time the sun was shining. The NREL paper itself (pdf) mentions that poorly integrated components and shade can reduce the effectiveness of the system by 14-68%, which is a huge range.

Now the funny thing about inverters is that in India, they've become a cottage industry. This article from the Times of India describes a former autorickshaw driver who has become a maker of home-made (literally) inverters.  The industry is in response to wild demand--India's  overstretched utilities stage rolling blackouts (load-shedding) throughout the day, and savvy homes use inverters and batteries to pull power when the grid is functioning, and use the saved battery power to run TVs and fans when it's not.

So here are a few thoughts:
1. India's inverters and batteries are creating a DIY smart grid, where consumers could draw and store power when its cheap and use it when its not. The US has a large multi-year initiative to wire ourselves up with smart grid devices that may allow homeowners to see and control when and how we use power, shop for power with real time pricing, and could allow utilities to reduce our consumption when prices are really high (hot summer afternoons.) (Here are some smart grid papers by  Dr. Massoud Amin.) India's solution is much funkier, and it may have a use in third world countries. But could we use some version of it in the US?  Would home energy storage, combined with appliances like, say,  air conditioners that store power as ice,  make our grid more resilient, lower carbon, and cheaper?

2. Some non-profit that's looking for a project should design a safe, stable, cheap inverter  that can be manufactured by low-tech entrepreneurs, creating jobs in India and elsewhere. The world is clearly going to need more inverters for solar --if not for shaky grids.

 


This article available online at:

http://www.theatlantic.com/technology/archive/2009/06/little-big-stuff-inverters-dont-get-no-respect/19265/