Tuesday, September 30, 2008

Power Up

Above is our latest green/sustainable/energy-saving initiative. Davis, owner of Bright Earth Solar, and his sister Rian just finished installing a dozen photovoltaic (PV) panels on the roof of our shop. The panels are mounted on a fixed frame and are capable of generating a maximum of about 2.5 kilowatts. Over the course of a year this array should produce enough power to offset about 60% of our current electrical load. An adjustable array would have improved the efficiency somewhat, but would have increased the chance of damage in high winds.

Inside the shop is the grid-tie inverter (on right) which converts the direct current from the PV panels to alternating current in synch with the grid. The inverter connects to a meter (center) and thence to the shop's sub-panel (left), where the power back-feeds to the main panel in the house. Our power meter on the house spins backwards when we make more power than we use, which is a pretty nifty thing to see. The payback period will depend on how fast electrical rates increase here in Vermont. If they average 4% per year (which seems pretty conservative), the payback period will be approximately 20 years. But the state is already talking about a 6% increase for next year, so we shall see.

Next month Davis will be coming back to install two solar hot water heating panels on the house. That will help a lot, since we burn oil for our hot water now.

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