Boston Gal's Open Wallet

Solar power ought to be the answer. The house faces south-east, lacks trees or other shadow-casting obstructions, and its flat roof offers ample space for a sizable solar array. At 720 feet up the hillside, it is well above the “marine layer” (the locals’ fancy name for morning fog) and gets about 300 sunny days a year. So what’s the problem?

It’s not even as though the place gobbles electricity. When the house was being rebuilt five years ago, the new roof came with over a foot of thermal insulation. The floor-to-ceiling windows along two sides of the structure were replaced with double-glazed “low-E” glass (the sort that blocks infra-red radiation), and thermal linings were included in all the exterior walls. Even during the summer, the air conditioner usually stays off.

Admittedly, the architect went overboard on lighting. Fully illuminated, the house demanded seven kilowatts of raw lighting-power before fluorescent lights replaced thirsty tungsten filaments. Overall electricity consumption is now a reasonable 8,300 kilowatt-hours (kWh) a year.

Given the local utility’s rate of 10.8 cents per kWh, that adds up to a modest $900 for the year—or just $2.50 a day. At those prices, solar energy simply cannot compete with juice from the local power-station, even with California-level subsidies.

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Here’s where going green gets tough. At today’s prices, your correspondent would have to stump up $48,000 for the solar panels alone. Add the cost of the switching modules, the power controller, the fault protector, the DC-to-AC inverter and the service panel—not to mention the installation charges and the contractor’s profit—and the final bill could easily come to $65,000.

What about incentives and tax credits? That depends on where precisely you live and how effective an installation you have. To get anything like a full grant in your correspondent’s neck of the woods, the array would have to be facing due south and tilted at an angle of 34 degrees to the sun. The first might be possible; the second would definitely not. At best, Mayhem Manor would qualify for about $12,000 worth of local assistance plus a $2,000 federal grant.

Borrowing the balance at today’s interest rates would mean repayments of roughly $600 a month for ten years, even after setting the interest charges against tax. And all that just to feel good about saving $75 of electricity a month. Better to buy a couple of tons worth of carbon offsets each year for $70 and have done with it.