Liquid Sunshine

May 1, 2007
Provide renewable energy for your customer's domestic hot water. For the majority of homes in the United States, heating domestic hot water is the second largest use of energy and consumes a daily diet of fossil fuels as much as 30% of each energy dollar spent! Because of this daily assault on consumer finances, the greatest return from a solar system investment will be achieved if you start with

Provide renewable energy for your customer's domestic hot water.

For the majority of homes in the United States, heating domestic hot water is the second largest use of energy and consumes a daily diet of fossil fuels – as much as 30% of each energy dollar spent! Because of this daily assault on consumer finances, the greatest return from a solar system investment will be achieved if you start with the domestic hot water.

When I started my own contracting business in 1979, solar systems were one of the things I planned to offer my customers. If I knew then what I know now, I would have railed against the death of solar shortly after Ronald Reagan took office in 1981 when he slashed the financial incentives with the stroke of a pen. We were experiencing an oil glut that lulled everyone into a fossil-fuel stupor. The oil shortage and long gas lines of just a few years prior were forgotten. Solar suffered a quiet death.

Over the decades that passed, I continued to have a back-burner desire to do something with solar energy. Then came rising fuel prices, energy shortages and our industry shift toward high-efficiency products. Our customers were, for the first time in decades, seeking out higher efficiency equipment and they were no longer afraid to invest in boilers, furnaces and water heaters that offered fuel savings.

If I was going to be actively promoting solar systems and selling them to customers, then it was going to be necessary to find reliable and well-engineered systems with excellent performance and the prospect for a long life. In the last few years I have researched solar energy online, in print, at events such as ISH in Germany and Solar World Congress in Florida and during factory tours of a solar system manufacturer. Recently, I installed my own system in my home in York, Pa.

Solar basics
Solar systems involve the same dangers we contractors already face. Electrical work, roof penetrations, plumbing and working with heavy components – on rooftops instead of basements. Permits and inspections will often be required. As professionals contractors, we have the insurance coverage required to protect our employees, bystanders and our customer's property from financial risk should anything go awry.

An active solar system needs to tilt at, or close to, your latitude, which is 39 degrees for our location in York. Our roof pitch is at 37 degrees, a 9/12 pitch, which I can vouch makes for a slippery and dangerous walk!

Safety is a serious issue for roof-mounted solar system installations and, according to OSHA and the Centers for Disease Control, more than 100,000 injuries and hundreds of deaths occur each year by falls from roofs. Having once worked high-steel construction, I can attest to the fact that falls do occur – in the blink of an eye a life is altered. Gravity will not be denied.

We own an utilized a confined-space-entry harness coupled to a shock-proof (meaning it can arrest a fall with our full weight) bull rope for entering subterranean pits while testing backflow preventers. Once properly anchored, this equipment served to prevent anyone from falling off the roof.

For an added measure of comfort and safety, I installed roof-jacks and planks. Installing them required curling back 14-year-old asphalt shingles to drive nails or screws into the roof's framing timbers and I utilized a heat-gun to soften each of the shingles, which helped avoid damaging them during the lift.

How water safety
Dealing with a hot-water heating system that can't be turned off meant that our potable hot water storage temperatures would fluctuate and, at times, rise well above scalding ranges. A must-have item was an American Society of Sanitary Engineering-certified 1017/1016 thermostatic scald-guard valve at the storage tank's outlet to protect my family from being scalded.

Our roof faces due south, although that's not necessarily an issue as solar panel frames which offer offsets for tilt and orientation are readily available. I naively assumed most, if not all, of our south-facing roof was suitable for panels. Trees that I thought were far enough away turned out to be shadow-casters during the late afternoon. My solar real estate suffered major shrinkage! But one lingering brightly lit sunny spot was just right for a solar array.

With the site assessment over and a spot for solar picked, the devil turned up in the details. Selecting a spot for the 120-gal. storage tank was easy. However, getting from roof to panel to storage tank was no walk in the park.

When I'd first suggested the idea to install roof-mounted solar panels, my bride replied, as most brides might "They'd better not be ugly, or you'll be removing them!"

The easy path from roof-to basement, as it turned out, would see tubing routed down through the garage beside the doorway used each day. No way, no how, un-uh! New construction might well be a no-brainer market for concealing the inner workings of solar systems, but retrofit is going to be challenging. Our only route available entailed drilling through a number of joists that rest over the concrete garage floor — a real stretching exercise and, as it turned out, the worst part of the entire installation.

Our solar-hydronics loop is what's called an "active system": filled with a 50/50 mix of water and glycol. This part really doesn't differ greatly from any hydronic zone in that careful attention is required to "think like water" and how it will flow while avoiding any potential air traps. Given that we wouldn't be able to turn off the sun whenever we experienced a system malfunction, the fluid trapped in the roof's solar array would quickly turn to steam and its glycol would suffer degradation. Ensuring the elimination of air is critical.

There were just of few remaining pieces of the puzzle to contemplate.

We lose power about six times a year. Typically, we'll return home from work to a house full of blinking digital clocks. Now that we were dealing with solar, power loss meant trouble.

Generating steam in the solar array would quickly occur, and the resulting temperatures and pressure spike would both degrade the glycol and a potential relief-valve dump to my catch-basin (a plastic trash can large enough to capture and hold total system content). Although we have a whole-house generator and transfer switch, it's not (yet) an automatic system. I wasn't yet ready to install a solar photo-voltaic electric generating system, yet felt I absolutely had to have a reliable back-up.

The Viessmann Divicon that I had selected incorporates the epicenter for power to operate the differential sensor control and a Grundfos low-watt circulator. I purchased an inexpensive backup battery power-pack to carry us over short-term power outages. For an added measure of safety, the Viessmann Solar System package includes an oversized thermal expansion tank designed to accept the full volume of the collector and higher pressure if steam is created during stagnation.

One more concern is that we can't turn off the sun at will once our storage is up to maximum storage temperature, which can be above 200° F with a vacuum tube system! A reliable means for shifting excess solar energy was needed so that we could go away for more than a day without worrying we'll overheat. A small radiator, typically used as an oil cooler for motorcycles will be utilized; a 12-volt computer-tower fan will be attached and powered by a small PV panel. For the present, we'll automatically shift the excess sun's energy into our sidewalk and garage snow-melt systems.

Tax credits
For a complete listing of federal and state-by-state tax and rebate incentives, visit the Database for State Incentives for Renewable Energy at The federal government's tax-incentive program can offset a solar investment by as much as 30% up to a maximum of $2,000 for qualified solar hot water systems and an additional credit of equal value for solar photovoltaic systems (visit EPAct-05.htm#solar). Partnering with a company whose system is already listed as approved can save you from heartache.

This credit is applied against taxes owed, so it may be necessary to alter payroll deductions to ensure maximum use of any credits. The great news is that you begin getting "paid" with the very next paycheck — an advance on your tax credit! That's tax-free money and that means every dollar is worth an average of $1.30 (visit www.ecs-solarcom/solar_tax_credit.htm).

In order to qualify for the federal or state tax credits and/or rebates, systems might need to be certified for performance by the nonprofit Solar Rating Certification Corp. ( or a comparable entity endorsed by the government of the state in which such property is installed.

I had learned at the 2005 Solar Decathlon in Washington that vacuum tubes have higher solar-capturing efficiency ratings than flat panels do. We installed Viessmann vacuum tubes last Thanksgiving weekend during cloudy weather.

The following day, while we installed the vacuum-tube clips, the sun was out in full force and we gained 30,000 Btu. Our storage tank holds 120 gal., which weighs 1,000 lb. and we had a 30°F rise. (An 82% efficient water heater would have used 37 cu. ft. of gas to grant a net of 30,000 Btu.)

For the next several weeks we had solid cloud cover. A vacuum-tube array continues to harvest solar energy in cloudy weather, and I observed a net gain of 2,000 to 10,000 Btu per day.

As I write this in April, the solar array is harvesting 45,000 Btu on sunny days, and I expect we'll double those numbers in June, July and August while supplying all our domestic hot water needs — liquid sunshine!

Dave Yates owns F.W. Behler Inc., a contracting company in York, Pa. He can be reached by phone at 717/843-4920 or by e-mail at [email protected].

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