Slam Valve Motor, supplying efficient steam engines for homeowners and professional solar installers
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             Bringing you the very latest in 18th century steam engine technology

The tiltable Fresnel reflector

To generate steam economically from solar power, one requires an economical solar collector. The tiltable Fresnel is the best choice for small to medium steam generators. It consists of galvanized steel water pipe, evacuated tubes available as spare parts for solar water heaters, and long strip mirrors. This design has no moving plumbing parts, and requires mere ounces of force to tilt each mirror to track the sun. The array itself does not move.  When mounted to a south facing roof, the cross section to wind is very low. This low cross section reduces strain which could be transferred to the roof. Stainless steel reflectors are maintenance free and recommended for long lifespan.

The tiltable Fresnel can be assembled easily in place by a homeowner or by a professional installer. Mechanical tolerances are wide, the tuning procedure compensates for many issues. The evacuated tubes require only an optical gain of 3 to provide reasonable efficiency to source steam for an engine, normal arrays run a gain of 10. Other collector designs have gains of 50 and up, requiring precision parts and alignment. The primary material expenses are the galvanized pipe, available at any hardware store, galvanized and aluminum angle stock, and the mirrors.  For those who would rather not build it themselves, check out  Sopogy.

King of the mirror material is #8 finish stainless steel, costing $5.50 per square foot in 4x8 sheets. Compare that with photovoltaic cells at $60 per square foot and up. The Fresnel generates comparable electricity per square foot as photovoltaics. The tiltable Fresnel saves you money by enabling you to do the work yourself. Download the instructions and the spreadsheet tool which will help you to select the proper size and configuration for your location. The Fresnel spreadsheet tool allows you to vary parameters like location, pipe length, shading, tube spacing, insulation thickness, and operating temperature to see the effect on total power generated.

flooded tube
tilt mechanism
                                stainless array      array tall