How It Works
Sunlight hits the photovoltaic panels, which convert solar energy into electricity. This electricity is used to first power the air compressor directly. When more energy is available than the compressor needs, the excess electricity powers an electrolyzer, which splits water into oxygen and hydrogen. The oxygen gas is vented to the atmosphere, and the hydrogen gas is stored in tanks behind the lab.

When the photovoltaic panels do not receive enough sunlight to power the compressor (either at night or when the weather is cloudy), the system automatically shifts to fuel cell operation. The fuel cell directly converts chemical energy into electricity by combining the stored hydrogen with oxygen from the air--basically the reverse of the electrolyzer. In this way water and sunlight, both natural and abundant, are used in a cycle to produce power. Hydrogen stores solar energy, so the power is available whenever it is needed.

A fuel cell is similar to a battery in that it converts chemical energy directly into electrical energy, but a battery requires recharging when it runs down. The fuel cell continues to produce power as long as it is supplied with hydrogen and air. This direct conversion of chemical energy to electricity is a shortcut from the usual way of obtaining electricity from a fuel, which involves burning the fuel, producing heat to boil water, and using the steam to turn a turbine that turns a generator, which produces electricity.

New interpretive signs are posted and a detailed brochure (view PDF version) is also available to explain the system to visitors.

System Components

A new fuel cell stack was added to the system in 2002. The first-generation SERC stack it replaced was three times as large, three times as heavy, and had approximately the same power output capacity. This change reflects SERC's continuing innovations in fuel cell stack design, helping to make fuel cells a more practical choice for portable, stationary and automotive power needs. The old and new stacks are shown side by side below.

The old and new stacks shown side by side

A complete system-wide redesign and rebuild occurred during 2006-2007. The PV array that once produced 7.5 kWp was degraded by 16%, producing only 6.3 kWp. The array was also providing less than 4.5 kW to the electrolyzer due to the fact that the electrolyzer’s operating voltage was far from the array’s peak power point. Additionally, the system was in need of a new fuel cell.

To increase system performance, overall efficiency, and make it run almost like new, SERC performed the following upgrades and design changes: installed state-of-the-art maximum power point trackers and DC-to-DC converters; rewired the PV array from 24 Volts nominal to 48 Volts nominal (reduced the resistive wire losses by a factor of four); and installed a separate 6 kW DC-to-DC converter to control current to the electrolyzer and facilitate maximum hydrogen generation during low and changing sun conditions. Read our newsletter article "Renewable Renewed," for additional information on the rebuild.