A Look at DIY Solar Energy Systems

Retrofitting Your Home for the Do-It-Yourselfer.

Your very handy around the house, and you’ve done your research on solar energy systems, now you’re ready to start retrofitting your home. However, have you considered how your home is setting?

Solar energy systems depend entirely on the sunlight. Therefore, any shading of the solar collection area between the hours of 9 a.m. and 3 p.m. will greatly reduce the system’s performance and cost effectiveness. It is very important that the orientation of the collectors must be within 30° of true south. This will vary as much as 22° from magnetic south in the United States. For this reason you must also analyze how your home is sitting on your site and answer the following questions truthfully: Do you have good southern exposure? Are there any trees, buildings, or other landscape features that will shade the collectors during the winter and could any of these features do so in the future? Remember trees do grow. If you do have a good southern exposure that isn’t shaded or at a risk of being shaded in the future than you can go to the next step, which is inspecting your roof.

As you already know, active solar heating systems use solar collectors/panels that heat either liquid or air that provides heat to the home. These collectors/panels are usually installed on top of the roof. Depending on the type of collectors/panels you choose, they can either be flush with the roof, or installed on racks, which elevate them above the roof’s slope to maximize the amount of solar radiation they receive. For this reason, it is vital that you have your roof inspected to ensure that it can support the added weight. This is especially important if you are using liquid-based collectors-and have an older home. So that you will have the reassurance that the weight of the system does not bring down your roof, have a professional inspector check the condition of your rafters. You also need to consider the potential wind loading the collector(s) could place on your roof structure. In addition to the structure, you also need to inspect the condition of your roofing surface material. If your have to resurface your roof, they collectors will have to be removed. If you have not purchased your solar heating system yet, then perhaps you may want to consider using roofing materials that already have PV cells incorporated into them. There are several different types of PV roofing products, which will compliment every type of roofing material from asphalt shingles, metal roofing, slate, cedar, and even concrete tiles. PV-active roofing products are produced separately from the standard roofing products.

Your next step is to consider the heat storage and transfer. As having the ability to store solar collected heat for nighttime use will increase the effectiveness of your solar heating systems. Often liquid solar heating systems use large, well-insulated water tanks that store solar heat for nighttime use as well as for cloudy periods. Determining the correct size of the storage system will depend on the amount of heat needed. The larger the heating requirement, the larger the storage volume required. If you do not have the space in you home for such a system, then it is possible to locate the storage system outside. However, this will require that the system, plumbing, and/or ductwork that lead to and from the system be very well insulated.

In addition, remember that most piping and ductwork runs inside walls, you may have to remove small sections of wall to do so.

Another important fact that you should keep in mind is that solar heating systems perform best when the collector temperatures are between 90°F and 140°F, which converts to 32.2°C and 60°C. Because of this, solar heating systems do work well with central or forced air heating systems as well as with radiant slab heating systems, but will not work well with baseboard heating systems.

There are two main types of passive solar retrofit options available to most homeowners, which are to increase the amount south-facing window area. This will allow in more sunlight. Secondly, if possible, convert an existing, south-facing masonry wall into an effective Trombe wall.

When you consider using passive solar energy, you must realize that it relies mainly on the natural movement of heat through convection, conduction, and radiation. Therefore, homes that have a more open design encourage natural air movement thus are better suited for passive solar heating. However, homes that have a more closed in design can use fans or blowers toy improve air circulation around room dividers or between rooms.

A Trombe Wall is any large, high mass brick, stone, concrete, or adobe wall, which has a glazing on the exterior south facing side. Trombe walls are not insulated as they absorb the sun’s radiant heat during the day then slowly release the collected heat into the interior at night. Any existing south-facing high-mass wall could be converted into a Trombe wall simply by adding glazing to the exterior south facing surface. There should be a gap of 3 to 8 inches between the glazing and the surface of the wall. You can reduce heat loss from the Trombe wall to the outside by placing Low-e glazing and drawing insulating curtain at night in the space between the glazing and the wall.

Finally, before you being any retrofitting project, make sure that you check your local covenants, zoning ordinances, and building codes as they may restrict or even prohibit the installation of a solar system on your property. There are countless homeowners associations across the country, which have prohibited any the installation of solar heating systems.

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