Solar Photovoltaic Water Heating System

Abstract

A solar photovoltaic water heating system is disclosed having a photovoltaic solar panel array, a storage tank containing water to be heated, a resistance heating element in the water to be heated. The water heating system matches the load resistance of the resistance heating element to the power that is available from the photovoltaic solar panel array in order to maximum energy transferred to the water in the storage tank.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Patent Application Ser. No. 61 / 733,595, filed Dec. 5, 2012, which is incorporated herein by reference.FIELD OF THE INVENTION[0002]The invention relates to a direct current (DC), photovoltaic (PV) water heating system. In particular, the invention is a photovoltaic water heating system that controls the electrical energy used to heat the water.BACKGROUND OF THE INVENTION[0003]Solar water heaters are known in the prior art. Kemp U.S. Pat. No. 451,384, entitled, “Apparatus for Utilizing the Sun's Rays for Heating Water,” discloses a solar water heating system that comprises a series of large diameter pipes connected in series in a wooden box, insulated with sand, and covered with green house glass panes. The pipes contained a volume of water that was directly heated by solar irradiance during the day for use in the evening. Subsequent to the Kemp patent, an improved solar water heating sys...

AI Technical Summary

Benefits of technology

The solar photovoltaic water heating system described in this patent is safer and more efficient than previous solar heating systems. It uses formulae and methods to determine power output from the solar panels more accurately, allowing for optimum energy delivery under a wider range of operating conditions. Additionally, the system stores higher temperature water in the tank but delivers it at a lower temperature to the users, resulting in more energy being stored during periods of high solar irradiance. The programmable control system also includes a high temperature limit switch to prevent water temperatures from exceeding the practical operating limit of the storage tank, prolonging the life of the tank and reducing warranty claims and issues.

Problems solved by technology

The solar water heating system of the Fanney et al. patent is, however, limited to a maximum of 7 combinations of resistance and those combinations are not mathematically optimized to achieve even step changes in power delivery from the PV panel array.

Images