Patent Application
20090223550
The present invention is directed to solar panels for roofs, and more particularly, to a building roof tile system and integrated solar energy system that includes a thermal solar collector which is designed to replace standard flat cement roof tiles or S-tile type roof tiles.
Solar thermal systems collect heat from the sun and use it to heat space or water. Solar thermal systems include components that collect the solar heat, store the heat, and deliver the heat to where it is needed.
Solar collectors are the components of solar thermal systems that collect solar heat. Typically, they sit on the roof of a house, where they are readily visible. There are several different types of solar collectors.
The most common type of solar collector is the glazed flat plate collector. This type of collector includes a weatherproofed, insulated box or frame containing a metal absorber plate with built-in pipes. Typically, it is two to three inches thick and resembles a skylight. Typically, it is also mounted directly on, or just above, the roof of a house so that is placed in the path of sunlight. The pipes built into the absorber carry a heat transfer fluid that is usually water, but can be a different fluid, such as propylene glycol. The absorber sits within the collector and is usually black or other dark color to absorb the most solar energy possible. The flat plate collector also includes a transparent or translucent cover over the absorber. The cover is typically a solar safety glass, which functions to slow down heat loss and trap solar energy inside the collector. Insulation on the bottom of the collector, behind the absorber, and on the sides, reduces conductive heat loss. Solar energy heats up water in the pipes causing it to circulate through the system, and passed to a storage tank located within the house.
Another type of solar collector is the evacuated tube solar collector that is made up of rows of parallel, glass tubes. There are several types of evacuated tubes, sometimes also referred to as “solar tubes” or “heat pipes”, used in this type of collector. The first type consists of two glass tubes which are fused together at one end. The inner tube is coated with a selective surface that absorbs solar energy well but inhibits radiated heat loss. The air is withdrawn, or “evacuated” from the space between the two glass tubes to form a vacuum, which eliminates conductive and convective heat loss. The second type consists of a single glass tube with a flat or curved aluminum plate inside the tube is that is attached to a copper heat pipe or water flow pipe. The aluminum plate is generally coated with Tinox, or similar selective coating. The third uses glass tubes that incorporate a water flow path into the tube itself. In this type of collector, the solar tubes or heat pipes act as heat absorbers inside larger evacuated glass tubes. The evacuated glass tubes act like a thermos to hold in the absorbed heat. The heat pipes hold a fluid that vaporizes at low temperatures and is resistant to freezing. The vapor rises in each of the individual heat pipes or solar tubes and warms up a carrier fluid in a manifold. After giving up its heat, the vaporized fluid condenses to a liquid, and then flows back into the base of the heat pipe or solar tube. The evacuated tube collectors must be properly angled to allow for the ongoing process of fluid vaporizing and condensing.
A further type of solar collector is the unglazed flat plate collector. This type of collector includes an absorber that incorporates channels for water flow. The absorber can be made from a variety of materials, including metal or extruded polypropylene plastic. The water flow channels capture solar energy to warm the water in the channels. Because unglazed flat plate collectors are light weight and come in different sizes, they are installed in a number of locations, such as on roofs, trellises or outbuildings.
Typically, however, solar collectors are mounted on roofs using low profile standoff mounts. Most collectors are installed just above, and parallel to, a roof. Usually, one or two collectors are installed. The standoff mounts hold the solar collectors above the roof surfaces, allowing air and runoff to flow beneath them.
Photovoltaic (“PV”) solar power generation uses photovoltaic arrays to convert solar energy to electricity. PV systems are made with semiconductors, like the materials used for integrated circuits. The semiconductors convert sunlight into direct current (DC) power. The basic part of a typical PV system is the cell, which is typically a small silicone square that generates a small amount of DC voltage. Cells are combined to create a PV module or panel. A module is a stand alone piece that is enclosed between sheets of tempered glass or plastic to protect the cells. The cells can be mono-crystalline, multi-crystalline or amorphous. PV systems typically include inverters to convert the DC current generated by the PV system into AC current and batteries to store power that is generated by the system.
PV solar modules can span a range of wattage outputs. One type of PV panel made by the General Electric Company, i.e., GEPVp-066-G, is designed to look like common concrete roof tiles so that the panels blend discretely with the concrete tiles on a roof on which they are placed.
In an exemplary embodiment of the invention, a building roof tile system and integrated solar energy system comprises a plurality of concrete roof tiles covering a first portion of the building roof, a plurality of solar electric roof tiles covering a second portion of the building roof, with each of the solar electric roof tiles including a plurality of photovoltaic cells connected together to generate electric power, and at least one solar thermal roof tile covering a third portion of the building roof, the at least one solar thermal roof tile including an absorber with pipes carry a heat transfer fluid for absorbing and transporting solar heat. The plurality of solar electric roof tiles and the at least one solar thermal roof tile each are sized, shaped and mounted on the roof so as to blend with the concrete roof tiles mounted on the roof.
The plurality of solar electric roof tiles can be positioned on the building roof so as to be contiguous to one another in an area corresponding to the second portion of the building roof, and the at least one solar thermal roof tile is positioned on the building roof adjacent to the plurality of solar electric roof tiles. The plurality of solar electric roof tiles and the at least one solar thermal roof tile can also be positioned on the building roof so as to be substantially in the center of the building roof and the plurality of concrete roof tiles can be positioned on the building roof so as to surround the plurality of solar electric roof tiles and the at least one solar thermal roof tile. Preferably, a plurality of solar thermal roof tiles are mounted on the building roof and used with the plurality of solar electric roof tiles.
Each of the plurality of solar thermal roof tiles further includes either a transparent or translucent cover over an absorber with pipes carrying a heat transfer fluid to trap and absorb solar energy inside the solar thermal roof tile or heat pipes inside of rows of parallel, evacuated glass tubes, the pipes acting as heat absorbers inside the larger glass tubes. Preferably, the absorber or heat pipes are a black metal designed to absorb a maximum amount of solar energy, and the heat transfer fluid in the absorber pipes or heat pipes transfers heat to a storage tank. Preferably, the absorber pipes or heat pipes in the plurality of solar thermal roof tiles are connected to one another so that cold water enters the pipes and hot water leaves the pipes as a result of the plurality of solar thermal roof tiles absorbing solar energy.
The solar thermal collector 20 of the present invention is designed to replace a standard flat cement roof tile, so as to be integrated with the cement tiles like the photovoltaic solar module 10 shown in
In the solar thermal collector 20, which is similar in appearance to the photovoltaic solar module 10, the PV cells 16 are replaced by an absorber plate 24 (or evacuated tubes) with built-in pipes 26, wherein a liquid solution transfers heat generated by the sun to a hot water tank located within a home. Multiple solar thermal collector 20 modules can be connected together through piping to amplify the transfer rate of heat from the sun.
As can be seen from
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
