a tuned solar panel would be optimised for the absorption of photons predominantly between 400 nm and 700 nm although other wavelengths may still be absorbed and generate useful energy whilst non tuned solar panels often rely on direct absorption of photons having ultraviolet wavelengths lt 400 nm ultraviolet photons are more energetic than photons at visible wavelengths but are generally emitted in small quantities by lighting such as fluorescent tubing and so the device would not be able to harvest sufficient energy to operate without utilising a tuned solar panel as above even other forms of lighting with different emission spectra have a common output in the visible spectrum which is relied upon to power the device the actuator draws around 0 4 w of power for around one second during actuation in this embodiment a 3v supply is provided and the current draw is around 133 ma during actuation if the sprayer is activated once every seven minutes 420 seconds then the average current draw per second will be around 0 316 ma if the interval is every fourteen minutes then the average current draw per second is around 0 158 ma for an interval of every twenty eight minutes the average current draw per second is around 0 079 ma the luminous flux density on the solar panel for it to provide this amount of power must be around 470 lux 230 lux or 110 lux respectively for seven fourteen and twenty eight minute intervals in order to replenish the amount of energy used in the given time period i e for the level of energy harvested to exceed the level of energy used the luminous flux density on the solar panel is highly dependent on the environment but typical values of the charging current.