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

[0010]A further feature of the present invention is a method implemented by the control system that causes the photovoltaic water heating system to store higher temperature water in the storage tank but then safely delivers water at a lower temperature to the users of the hot water, thus allowing more energy to be stored in the tank during periods of high solar irradiance.

[0011]Another feature of the present invention, the programmable control system which includes a high temperature limit switch to insure water temperatures do not exceed the practical operating limit of the particular storage tank being used, thereby prolonging the life of the storage 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.

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