Solar Cycle Kilns - Special Variations:

Off the electric grid operations using solar panels to power the fans.  Photo voltaic panels can be used to generate the electricity to power the fans in the kiln.  The brighter the sunshine, the faster the fans will blow!  The higher initial cost gradually pays off over time.

100% Convection Solar Cycle Kiln uses no electricity.  Locating the wood  chamber above the solar collector surface allows convection to circulate the    air with no added energy.  One solar cycle was built on the top edge of a quarry.  The collector panel was leaned against the 50 foot high stone wall of the quarry, creating enough hot air flow to push up through the lumber piles to dry the wood.  Do not use a solar collector built into the ground - that design must heat the earth first before you start to dry any lumber.  A low mass collector is        essential to solar kiln drying.

Solar/Wood Hybrid Cycle Kiln.  A large lumber operation can burn their wood waste to add heat to the kiln to maintain the drying cycle on cloudy days.  Caution is needed when adding wood heat to prevent over drying of the lumber. 

Greenhouse Solar Cycle Kiln. This design is for tropical locations where the sun is directly overhead and the ambient temperature is relatively high.  The same insulated window, black metal layer, and small fans are used.  One design is a simple, inexpensive  greenhouse where the lumber piles are in the one room of the structure.  Another design would be a well insulated building with a greenhouse style collector as the roof.  The latter design keeps the heat inside at night, where the first allows the heat to radiate out the window so you start cold each day.  It is recommended that the lumber be predried under another roof, but this design would work starting with fresh sawn lumber.  This design would also work as an inexpensive start up kiln for a new operation.