For the past three years, his board at the 15-story Cabrini Terrace at 900 West 190th Street has been trying to install a photovoltaic (PV) system on the co-op's garage. Solar, Dwyer asserts, makes sense because his building is at one of the highest points in Manhattan, eliminating concerns about being in shadow, and is tall enough that it's prudent to have back-up energy for elevators and water pumps in case of blackouts.

While PV systems have been available since the 1970s, contractors who install them say condos and co-ops have not taken advantage of financial incentives and tax breaks as often as single-family homeowners and commercial owners have. "We're still in an early-adopters phase," explains Anthony Pereira, president and CEO of altPOWER, a PV installer. Con Edison says 141 PV systems are in use in New York City and in the utility's Westchester County territory; about half are residential projects.

One way PV systems make economic sense is "net-metering," which is when the solar equipment generates more power than needed and the excess flows back into the overall Con Ed grid. Essentially, your meter runs backward and you get a cash credit for generating power. But Con Ed limits net-metering to 10 kilowatts — a limitation that makes some buildings hesitate, says David Buckner, president of Solar Energy Systems, which has been installing solar in the area since 1998. "The issue of [low limits on] net-metering is really a killer right now," he explains. New Jersey, Pennsylvania and Massachusetts allow higher levels of net-metering, he says. Con Ed maintains its lower limit is needed for safety reasons, while not addressing the utility's economic disincentive for giving credits for larger amounts.

An additional hurdle is that under New York City's electrical code, components and installation of solar-power systems must be certified by a nationally recognized testing agency, such as Underwriters Laboratories (U/L). This can add $1,000 to $3,000 to installation costs.

Even the New York State Energy Research and Development Authority (NYSERDA), which has handed out about $22 million in solar incentives over eight years, isn't always optimistic. A spokesman notes that buildings with small roofs crowded with water towers and air-conditioning units have little room for a PV set-up. (Buckner estimates a 10-kilowatt system requires about 1,000 square feet of roof space.) Also, many shorter buildings are shaded by taller ones for a significant portion of the day.

On the + Side

At the same time, several recent developments might make it easier for condos and co-ops to go solar. Under old laws, if you installed a residential PV system, you qualified for a state tax credit only if your system were 10 kilowatt, which is small for a multi-unit building. But on July 10, 2007, Governor Elliot Spitzer signed a bill that allows installations of up to 50 kilowatts to apply for the tax credit. The co-op or condo gets a 25 percent credit based on the cost of the project; co-op shareholders get a percentage based on their share, and condo-owners simply divide the amount — either way, capped at $5,000 credit per individual.

A bill introduced in May 2007 by State Assemblyman Steve Englebright would boost the amount of net-metering permitted in the city from 10 to 2,000 kilowatts. The bill passed the Assembly in June and is awaiting a companion bill in the State Senate. Likewise, State Senator Robert Menendez introduced a bill in March 2007 requiring utilities to permit net-metering up to 2,000 kilowatts. And in December 2006, Congress voted to expand the existing 30 percent solar-installation tax credit to the end of 2008.

Additionally, Mayor Michael Bloomberg has proposed a property-tax abatement equal to 35 percent of the installation costs of PV systems that are initiated between 2007 and 2009.