Renewable Energy

JWD Ltd undertakes research into and evaluation of renewable energy products. In April 2007, a solar hot water heating system was installed, consisting of 3 sq.m of Thermomax heat pipe evacuated tubes,  The performance of the system has been measured and is shown in one of the photographs above.

Several products have been developed and are undergoing test, including a solar-powered well pump, which might have an application in third world countries, a remote controlled wood burner circulation fan, and various digital lighting controllers based around PIC microcontrollers.

Much research has been carried out into using solar power to run RF hubs/gateways and other equipment where a mains source is not available. These use some of the latest Linear Technology intelligent charger ICs and maximum power point tracking (MPPT) techniques together with supercapacitors and modern battery systems such as Lithium Polymer cells.

Shown below is data gathered using a small USB logger, for a NiMH battery under load, replenished by a solar charger over a period of a few days in October.  The moving clouds can be clearly seen as fast changes in voltage with time, along with three days of total cloud cover. There remain some interesting and unexplained features in the plot.