Sun Bathing

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Suddenly solar thermal is hot. Pun intended. Harvard University has mounted a solar thermal installation atop a freshman dormitory, to heat water for a system that provides all the hot water for the buildings in Harvard Yard. Here in Gotham, the City University of New York recently launched an interactive, digital New York City Solar Map, which shows solar installations all over town.

For the record: a solar thermal system uses the sun’s energy primarily to create heat. A photovoltaic (PV) system uses solar energy to produce electricity.

If Harvard can go solar thermal, what about New York City’s co-ops and condos? Solar thermal is a cutting-edge approach to heating the water for showers and baths, dishwashers and laundry machines – even indoor swimming pools. So for the board that wants to be at the forefront of renewable energy and also reduce a building’s fuel costs, what are the rewards – and the challenges – of installing a solar thermal system?

Solar Thermal Systems: A Primer

In a solar thermal system, solar panels, either flat-plate collectors or evacuated tubes, are installed on a roof. In the Northeast, they are often mounted at a 40-degree angle, but sometimes they lie horizontally. A flat-plate collector contains tubes filled with propylene glycol (antifreeze), which absorbs and holds the sun’s heat. The vacuum tube design is made up of long cylinders; the vacuum acts as a perfect insulator in very cold weather, while inside the vacuum sunlight is converted to heat, which is then transferred to a standard piping system that runs glycol. In each case, heated glycol travels along pipes to a water-storage tank (usually in a building’s basement) and heats potable water, which then travels through the building’s pipes to residents’ apartments.

One myth holds that solar thermal can’t work in a Northeastern city known for its temperate climate. But the reality, as Canada and northern European countries have demonstrated, is that a solar thermal system can collect and store the sun’s energy year-round, although obviously the sun’s heat will be more available during spring and summer months. At other times of the year, a building’s conventional water-heating system can kick in if necessary.

But considering that 30 percent of a building’s energy is used to heat water, if a solar thermal system can offset that by 50 percent, then you have a 15 percent reduction in the total energy for a building. That’s a considerable reduction, in terms of both fossil fuels and their emissions, and in terms of cost. A well-designed system can last 20 to 30 years, although the glycol probably needs to be changed after seven years. Solar panel manufacturers usually have warranties of 10 to 15 years.

Is Solar Thermal Right for You?

Quixotic Systems is a Manhattan-based company that designs urban solar systems, both thermal and PV. Quixotic was one of the first eligible installers in New York State as well as one of the first New York State NABCEP (North American Board Certified Energy Practitioners) installers. Community Environmental Center (CEC) is a Queens-based nonprofit, founded in 1994 to bring energy efficiency and green solutions to new and existing buildings. CEC is licensed by the New York State Energy Research and Development Authority to install solar thermal systems in New York State.

Over the past year, our two firms have partnered to integrate solar thermal systems in a variety of New York City buildings. Based on our experience, we have concluded that, in New York City, the optimal residential building for a solar thermal system would be six to eight stories and have 2,000 or more square feet of usable roof space.

Certainly, solar thermal systems can be designed for taller buildings – and have been. But one of the requirements of almost any system includes installing a large pipe that runs from the collectors on the roof to the water storage tanks in the basement, and the more piping, the bigger the investment in materials and labor.

And speaking of roofs, in New York City, they often look spacious from the layperson’s point of view. But in addition to penthouses and water towers, they also contain a slew of vents and stacks and other obstacles that potentially could interfere with an array of solar panels. So in the best of all possible worlds, 2,000 square feet of net, uninterrupted square feet is what’s called for.

Of course, whenever a co-op or condo considers a capital improvement, the elephant in the room is money. A solar thermal system is indeed a substantial investment. But a federal tax credit is available to assist with upfront costs (and in 2011 only, a federal tax grant, which means a check in the mail). The federal government provides a 30 percent tax credit for solar thermal installations for commercial businesses, and co-ops or condos can qualify for this tax credit, although those with commercial space might have an easier time. If your building’s solar thermal system costs $50,000, the building would claim a $15,000 tax credit for the year it was installed.

There is also accelerated depreciation, and in 2011 only, the federal government is allowing 100 percent depreciation. But again, depreciation is really for commercial systems and would probably be difficult for the co-op or condo without commercial space.

Still, even within those limitations, 2011 begins to sound like a very good year for a solar thermal installation.

Solar Thermal for a Park Slope Co-op

The property at 176 Sterling Place is indeed a small building. It has four floors, not including the basement, and 12 units, a few of which are duplexes. Built in 1906, it went co-op in 1985. The board treasurer, Robert Dascoli, proposed the idea of installing both solar thermal and solar PV – a hybrid system.

“Our board president tries to be very green,” says Dascoli. “But also, it was 2007, and energy costs were absolutely soaring. Our water bills were going up 15 percent each year, and our Con Ed rate was also going up. National Grid, our gas purveyor, seemed to raise their rates, and the dryers in our basement use gas. We were looking for alternative energy routes.”

As Dascoli learned from Quixotic, the building was a good candidate for solar thermal. “The part of the roof that the solar thermal panels reside on is at the very back of the building, and it’s basically dead space,” says Dascoli. There are no tall buildings around 176 Sterling Place, no trees, and no water tower on the tar roof. In short, the building receives an abundance of sunlight.

“The board liked the idea,” says Dascoli, “and with Quixotic’s help we made a detailed analysis of cost/benefits and put the plan to the shareholders.” In 2009, Quixotic installed the system.

It’s a pretty innovative system, because the six solar thermal collectors lie flat. If they had been at an angle, they would have projected shading onto the nearby solar electric panels, which are very sensitive to shadow.

The basement of 176 Sterling Place contained two 100-gallon hot water storage tanks, and Quixotic brought in three more for the solar thermal unit. Quixotic ran the pipes outside – along a side of the building, says Dascoli, “that no one accesses, so there are no problems.”

Sterling Place’s solar thermal system cost about $60,000; today it would probably cost around $50,000 because of declining price tags for equipment. The whole energy project, including PV installation, came to more than $100,000, which the building financed with a line of credit at National Bank (headquartered in Virginia). Currently, says Dascoli, the building is paying that down “in chunks, with the help of the savings from energy, a New York City property tax credit, and a lump-sum check from National Grid.”

Benefits, Bureaucracy

The solar thermal system at 176 Sterling Place heats roughly 70 percent of the building’s hot water. When the system began running, Dascoli reports, the building saw its gas bill go down “at least $200 per month. It was almost instantaneous.” Quixotic monitors the system from a remote reader, but there have been no technical snafus – although the tornado that tore through Brooklyn in September 2010 left two cracked glycol tubes in its wake (the tubes have a five-year warranty).

The only thing that has kept Dascoli awake at night is the city’s red tape, largely related to a tax abatement that was painfully slow in coming for the PV installation and ultimately drove up the costs of the entire project. As all of us at Quixotic and CEC have learned, getting a solar thermal system up is sometimes faster than getting it approved. We usually say that a system will be up and running within three months. Robert D. LiMandri, commissioner of the New York City Department of Buildings, is concentrating on reform in this area, and Quixotic has an in-house expediter.

Assuming that the red tape can be untangled, Dascoli of Sterling Place avers that “every co-op should consider doing this if they can sustain the up-front costs.”