Ringueberg Solar Panels

In the effort to improve solar system efficiency, attention has been directed mainly toward improving collector and storage systems. The third side of the coin, distribution efficiency, has been largely ignored.

For example, SERI has a very active program for testing collectors, but no program at all for testing distribution systems. While this "oversight" is understandable, it represents a definite shortcoming. Durango, Colorado's Nairn Ringueberg has set out to change that.

Ringueberg, a retired engineer, turned his attention to solar systems several years ago. Ringueberg designs the systems and his son, Bill, who has a company called San Juan Solar Systems, does the fabrication and installation. The first systems were typical water collector and water storage systems with a heat exchanger for forced air distribution.

All of that has changed in the past three years, however. The collectors for Ringueberg's solar systems are still fairly prosaic: one plate of glass for cover, corrugated aluminum roofing painted black for the collector surface, continuous loop copper tubing bonded to the back of the collector for heat pickup and, depending on the particular installation, backing of one or two inch thick rigid insulation.

The exciting and innovative part of the Ringueberg system is on the distribution side. Ringueberg uses radiant heat panels in the floors, on the walls, or in the ceilings, depending on the particular installation criteria.

Radiant heat is nothing new. In fact, it is man's oldest external source of heat--consider the sun and campfires--for instance. Radiant electric heat has been around for quite some time, and there is nothing new about running pipes through concrete floors for radiant heat purposes either.

Despite the above, the Ringueberg system is exciting because it permits the use of low temperature water. And, the efficiency of solar systems of the kind we are discussing increases dramatically at lower temperatures.

Let's take the Ringueberg radiant wall and ceiling panels as examples. The panels consist of flat aluminum sheets with continuous loop copper tubing bonded to the back. For perimeter walls and ceilings, insulation is used behind the panels; usually, on inside walls no insulation is necessary.

The panels can be glued, nailed, or screwed to a wall or ceiling; or, they can be built directly into the structure. They can be painted the color of the wall (any color is okay, though, generally, dark colors are preferred), or they can be covered with wall paper--you name it. In one installation, where the panels were placed up near a high ceiling, the panels were painted black for decor reasons and were tilted down slightly to direct the radiant heat toward the floor.

As water is circulated through the tubing, either directly from the solar collectors or from storage, the heat from the water "spreads" across the entire face of the radiant panel and is then radiated into the room. The temperature of the water used can be only a few degrees above the desired temperature and still do an effective job of keeping those in the room comfortable.

Because the Ringueberg radiant panels are relatively large, they do not require the 170° to l80° temperatures needed to make conventional hydronic systems effective.

The system can operate even when the temperature of the water being circulated is below desired room temperature, so long as the circulated water is warmer than outside ambient temperature or warmer than the temperature the wall would be without circulating the water. Why? Because the water acts to temper wall temperature and thus reduce the heating task for the backup system.

Ringueberg favors a backup system that is entirely separate from the solar system. His favorite backup heat is a wood stove, in areas where wood is plentiful and cheap. Otherwise, he suggests electric or natural gas backup systems.

Ringueberg cautions that the water storage tank should not be too large. He suggests about 1.25 gallons of storage for each usable square foot of collector surface. His installations have varied from one gallon per one square foot (the water frequently gets too hot) to 1.4 gallons of water to one square foot for a radiant concrete floor application. Local weather patterns, degree days (DD), structure characteristics and installation features should all be considered in sizing the storage capacity and in sizing the radiant panels.

How well do the systems work?

While comprehensive technical data are not yet available (a situation which is by no means unique to the Ringueberg systems and their applications), the preliminary, non-technical data seem very favorable.

The first installation was at Bear Ranch located several miles north of Durango. The "ranch" is a combination home, restaurant, sport shop, and health spa. The 5,000 square foot building is four stories high. The first three floors are concrete with copper tubing imbedded in the concrete about one inch below the floor's surface.

Ringueberg suggests laying the slab and then laying a one inch "light-mix" layer of concrete on top of the slab, with the copper tubing embedded in the light-mix layer. The collector area is 420 square feet with a 600 gallon storage tank. Backup heat is provided by a fireplace in the living area and a wood stove in the public area of the building.

The winter of 1978-79 was one of the worst in living memory in this area. Record to near-record snowfalls occurred, and, though there were no record temperature lows, it was an unusually cold winter -- nearly 1500 DD in January compared to the average of just over 1200 DD for that month. There was between 15 and 20 per cent more cloud cover than usual. Throughout this cold, snowy, cloudy winter, Ruedi and Leith Bear, the owners of Bear Ranch, reported using only four cords of wood for the entire winter!

During the 1979-80 winter, which was cloudy and snowy, but considerably warmer, the "ranch" used only one cord of wood! Part of this difference is due to the construction of a greenhouse for passive gain. The greenhouse was completed early in 1979 and did not contribute much to the 1978-79 heating load, but it worked very well during the 1979-80 winter, according to the Bears.

One of the really big advantages that the Ringueberg system has is the relative ease with which it can be used as a retrofit for solar heating in existing structures.

Maynard and Elva Fox have done just that. Maynard is a retired college professor. He installed ten collector panels on the roof of his house. Inside, he placed radiant panels in several of the most-used rooms.

In the living room the panel was placed in the wall beneath the picture window. The panel is 19 inches by 12 feet. In the kitchen the panel covers part of one wall and is 3 feet by 6 feet. In Maynard's study, the panel was angled above the closet doors. This panel is 14 inches by 7 feet. The panels blend in so well that most people do not know they are even there, let alone that they are the main source for heat distribution.

The ten roof panels provide about 175 square feet of collector area; the radiant panels cover about 162 square feet. The water storage tank, 160 gallons, is too small, causing the system's water to get too hot. The system would be more efficient with greater storage volume or with more radiant panels; Maynard thinks he will install at least one more radiant panel in the house.

The Fox installation was not difficult for Maynard, even though he is not a professional builder. By doing most of the work himself, he was able to install the entire system for about $4,000. Federal and state tax incentives will reduce this cost figure substantially. Both Maynard and Elva are satisfied with the system. They like the radiant solar heat. Backup heat is provided by a wood stove and, on relatively rare occasions, by the electric radiant system that was installed 15 years ago when the house was built.

The Fox installation is particularly important because the majority of solar applications will have to be retrofits if solar is to become an important energy source in the near future.

Nairn Ringueberg is a quiet, unassuming man. Without fanfare, government funds, or a large budget, he has come up with an exciting solar system. The Ringueberg systems operate at high efficiency because they can operate at temperatures that are a few degrees above--or even below--the desired room temperature. The systems are simple to fabricate and install. There isn't much to go wrong with a properly installed system. The systems lend themselves well to retrofitting, as well as to new construction. They are cost effective. And, the do-it-yourselfers can build and install their own versions of the Ringueberg San Juan Solar System.

Mr. Ringueberg doesn't want to get rich from his "invention." He just wants the world to recognize the system's many positive features and he wants to see several million installations in the years ahead.