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I have met many people who are in favor of solar energy, but are put-off by the way the collectors look, and some even think the collectors are ugly. When targeting new and retrofit solar heated building projects, this can become a pivotal challenge to the owner’s choice of solar heating. No solar heating design will be acceptable if the owner thinks it is ugly. So, an “effective” design will find a compromise that remains affordable but mitigates or conceals most of the “ugliness” in question. Every building project is different in terms of shape, size, geometry, and site layout. The art of collector placement is to make use of the existing features of the site to elegantly conceal the panels and/or integrate the panels into the structure of the building. Also, using the surrounding environment so that the panels are compatible with the architecture and landscaping features.
Let’s take a look at some examples of successful solar thermal building projects from recent years. In all these installations, I designed the piping systems using similar “new standard” hydronic primary-loop configurations. But, the collectors were mounted in a variety of different ways. There are various degrees of attention given to concealment and integration using the techniques described below in any combination that could be best applied in each case. In these examples, the extra cost to conceal or to integrate the panels was a very small fraction of the cost of the heating system, resulting in a much more attractive final appearance.
Portrait or landscape
Traditionally, flat plate collectors have been most widely manufactured with interior headers (manifold pipes) running parallel to the short sides of the collector. The ends of the header pipes protrude through rubber sealed holes in the long side of the frame near the corners. This is the classic “portrait” style collector, most easily installed in a “tall” orientation, allowing adjoining collectors to be plugged together side-by-side using couplings or unions. This classic construction uses a minimum number of tubing welds on the manifolds, and uses the shortest manifold possible, resulting in a low manufacturing cost. When mounted side by side the tall way, a minimum amount of plumbing and racking hardware is required and the installation is typically lower-cost as well. The collectors shown in Example 1 are constructed and installed this way, and rise about 10 feet off the ground. They are Heliodyne 4 x 10 panels connected together with factory-provided threaded unions with O-ring seals
The most common alternative to soaring-skyscraper collectors is “landscape” mounting, or “low” mounting. Many flat plate collectors can be turned on their side and mounted that way with the proper piping and racking modification. (Check with the manufacturer’s installation instructions to make sure this is not prohibited.) With closed-loop glycol systems this can be done with impunity. With drain-back systems, the gravity flow-path through the collector and all the piping must always slope down hill, which restricts the use of some collectors and some orientations. All the systems shown in these examples are closed-loop glycol.
External or internal headers
Some collector plates do not have pass-through headers, and provide the installer with only one inlet and one outlet pipe nipple. To connect these together in a group with reverse-return piping, external headers may be required to be added by the installer. The collectors shown in Example 2 are like this. External headers covered with light brown pipe insulation can be seen running along the top and bottom of each bank of collectors. Copper tees allow the collectors to be properly connected together with balanced flow. These collectors are Yazaki stainless steel wetted plate panels with 3/8-inch threaded pipe nipple connections.
When a classic portrait-style collector is turned on its side and mounted the low way, external headers must also be added. This is because the factory-provided pass-through header outlets are pointing up and down. A header with tees can be used to correct the orientation of the pipes and can also be arranged to provide balanced flow through each panel. Pipe hangers may be needed to anchor the collector header pipes to the mounting rack so that the collector plate can not slide down hill. The collectors shown in Example 3 are installed this way, using panels provided by Caleffi using threaded unions with flat gaskets on the collector connections. This is a retrofit hydronic heating system converted to “New Standard” primary-loop piping and standard control system in Virginia.
A few collector manufacturers offer collectors that are constructed so that they can be mounted the low way in “Landscape” orientation and still plugged together side by side. These collectors are made with internal headers that run parallel to the long side of the frame, and the header pipes protrude out the top and bottom of the short frame. This type of collector is available in metric sizes that are about three feet tall when mounted, and U.S. standard sizes that mount about four feet tall. Example 4 shows a metric version using Viessmann panels that employ a unique coupling made of a metal accordion tube with O-ring pipe plugs to connect the headers together side by side.
Remote placement and screening
Some buildings just don’t have enough room for collectors on the roof. Some don’t lend themselves to solar panel attachments because of their architectural integrity or other factors of the shape, orientation or structural materials. In these cases, the easiest place to put collectors may be remote from the building they heat. An existing out-building nearby can often serve as a platform for the collectors, or a ground-mount can be constructed on concrete footings. I generally look for a location that is not more than 100 feet from the mechanical room, although some have been further than that. Example 3 shows this type of remote ground mount located about 50 feet from the mechanical room and uses a standard Caleffi solar pump module for solar heat collection. Example 1 requires a pipe run of over 200 feet to the basement and the pumps and PV panels were upsized to overcome the extra pipe resistance. The collectors heat everything in the house including the radiant floors the domestic hot water and the pool in front of the house.
Remote collectors should be screened from view whenever possible. This can be done in a number of ways. Trees can be used in front, behind or surrounding the collectors as long as they don’t shade the face of the panels during the day. Example 1 used both existing trees and strategically placed newly planted trees to surround the collectors. In Example 3, the panels are low with trees behind and to the side. This provides an aesthetic backdrop to soften the appearance since the tops of the trees counteract the linear look of the panels. Placing the collectors in front of a backdrop of any kind can be surprisingly good camouflage. Collectors placed in front of a south facing hill are much less imposing than placing them at the top. So, putting them in front of a retaining wall, privacy fence of other large object can be an effective technique.
In Santa Fe, we have a section of downtown that is a historical district with a strict code prohibiting visible non-historical installations. The only way around this building code is to make the collectors invisible. Since flat roofs are common and traditional in the historic zone, we needed a low collector about half the height of conventional low collectors so that we could hide them behind historical parapet walls. We have used these panels in many projects, even outside the historic zone. Example 5 shows an installation using half-height collectors. They are 2 x 10 panels custom-made by Solar Skies, and as you can see from the photo, the collectors are invisible when looking at them from the street level.
Integration of the solar panels into the building design is best accomplished in consultations with the architect or designer early in the design process. Metric sizes and low-height panels can be screened more easily by architectural details like parapets, stepped roofs, and other horizontal elements. Sometimes a garage or shading structure can be designed specifically to hold panels. Collectors can be mounted flush and parallel to the lines of the building, if the building is designed with these surfaces facing south. Example 6 shows a project that employed all of these techniques in a new construction. The collectors appear on the house in three separate groups: vertical flush wall mount, tilted flush roof mount and flat roof with parapet screen. When viewed from the road, the collectors tend to blend into the character of the building.
Less is more
There will always be some solar enthusiasts that regard collectors as attractive objects and display them proudly as billboards of honor. Example 2 is just such a homeowner. The collectors hit you like a pie in the face as you drive up the road. But for the rest of the population, who choose to focus less on the technology and more on aesthetics, when it comes to panels, less is more. The best solar placements allow the architecture of the house to dominate while the solar features are under-stated. Given that beauty is in the eye of the beholder, all the low mount and flush mount collectors in these example photos seem more attractive than the alternatives. If this fits into your next project, you may find that solar heating gains easier acceptance when you can make the panels virtually disappear.
These articles are targeted toward residential and small commercial buildings smaller than ten thousand square feet. The focus is on pressurized glycol/hydronic systems since these systems can be applied in a wide variety of building geometries and orientations with few limitations. Brand names, organizations, suppliers and manufacturers are mentioned in these articles only to provide examples for illustration and discussion and do not constitute any recommendation or endorsement.
Bristol Stickney has been designing, manufacturing, repairing and installing solar hydronic heating systems for more than 30 years. He holds a Bachelor of Science in Mechanical Engineering and is a licensed Mechanical Contractor in New Mexico. He is the Chief Technical Officer for SolarLogic LLC in Santa Fe, New Mexico, where he is involved in development of solar hydronic control systems and design tools for solar heating professionals.