The Model SPK Solar Panel makes it possible to use Dwyer flowmeters in remote applications where a reliable source of electricity is not available or practical. The SPK is intended for use with a standard 12V, 22 to 33 amp-hour sealed lead acid battery (not included). It comes standard with a charge controller and corrossion-resistant mounting hardware. The SPK can also be used to provide up to a 40-day back-up power supply for periods of darkness.