As a solar consultant, Paul Shippee offers solar design strategies and planning for clients looking to save conventional fossil fuel energy, reduce their carbon footprint, use solar energy to heat their homes and domestic hot water, and install PV systems. He offers Solar Design and Natural Building workshops at the Crestone Solar School. His own home in Crestone, Colorado is 100% solar heated. "My house itself is a living solar laboratory for learning as it displays passive solar heating with integral thermal storage, an active solar system on the roof that pumps solar heated water into the adobe floor and heats the domestic hot water as well."
In other words, Paul knows his stuff. Here's what he had to say in answer to some of the most commonly asked questions on solar thermal power. Find out about roof penetration, maintenance, the heat distribution process, and more.
How is a solar heating system typically installed? Is there roof penetration involved when installing flat plate solar collectors? What sort of maintenance will the roof require once the panels are removed?
Solar heating collectors can be mounted on the ground or on a roof. A structural rack system is constructed to hold the flat plate solar collectors at the required tilt angle. On the ground these rack structures are bolted into concrete piers typically, whereas on a roof mount holes must be drilled through the roof so strong bolts can be secured below to the roof framing members. With good design and professional roof hole sealing materials and techniques, there should be no problem with wind loading or roof leaking.
What types of distribution systems are typical for active solar thermal (heating)? How is a solar heating system maintained? Is there a lot of work involved?
Solar heat is distributed to the home in a variety of ways. In new homes, plan to distribute the solar heat gained from liquid active solar systems in the floors, which ideally are made of concrete or adobe to provide massive heat storage without overheating. This is the easiest, most effective, comfortable, and efficient heat distribution arrangement by far. In retrofit situations with older homes, the solar system must be tied into the existing heating system, usually requiring higher distribution temperatures which then degrade the efficiency of the solar collection. This higher temperature requirement is because the older conventional heat distribution systems run on oil or gas, which provide higher temperatures naturally.
Solar system maintenance can vary a lot. Typically, pump parts wear out, sensors that operate the controls fail, and anti-freeze needs replacing every 5-10 years. Additionally, if the original solar system was installed without proper fail-safe controls to protect the system parts under all conditions, then catastrophic failures can involve expensive repairs. Installation by amateurs, therefore, is not recommended.
If you aren't building a home from scratch, what are the easiest ways to incorporate passive solar heating into your home design?
Consider adding thermo-siphon air collectors onto the south side of the building, or adding a solar greenhouse, especially if the home is long in the east-west direction, and that long side is facing south, with no significant shading on winter days from trees or buildings. Solar greenhouses are popular because of the extra space and warmth they provide in winter for heating and food growing.
How does one use an aquarium as thermal mass? Which type of fish would you recommend for these temperatures?
Research in the past done at the New Alchemy Institute showed how to grow tilapia fish in tall, round, plastic, transluscent solar thermal storage water containers placed inside a solar greenhouse.
When the solar water tank and collectors are no longer in suitable condition to use, how are they typically disposed of? Are there ways to recycle/reuse the materials, and are these methods easily or frequently applied?
Most of the materials used in solar collectors –glass, aluminum, copper- are easily recycled.
What other questions do you most frequently encounter from homeowners looking to go solar? How do you address these questions?
A popular question is: how much does it cost? Is it maintenance free? How long will it take to recoup my investment in the solar equipment and installation through conventional fuel savings? The answer to the last question is unknown because it depends on the future rise in conventional fuel prices. One can only guess, but the direction is up, that's for sure, now that we are entering the peak oil era - which simply means the end of the era of cheap energy. The party's over as Richard Heinberg says! Usually the installed cost of an active solar heating system on a modest size home will be between $20,000 - $30,000 in my recent experience. For PV it might be around $9 per peak watt. Both these costs can be offset some by various subsidies now available.
-- If you benefited from this portion of the interview, look out for parts 2 and 3 of my discussion with Paul, when he will break down your solar collector options for harvesting solar thermal power and discuss his outlook on the solar thermal and PV industries. Thanks for all the info, Paul!