Solar cells or photovoltaic (PV) cells are devices that convert sunlight to electricity. Solar cells are typically manufactured from semiconductor materials, which may be doped with a variety of “impurities” to enhance the absorption of photons, increase conduction and/or reduce band gap energy of the cell (i.e., the amount of energy required to knock an electron loose). In various solar cell designs, when a photon reaches or “strikes” components of the PV cell, a certain portion of the photon or its energy is absorbed into the semiconductor material and “knocks” one or more electrons loose, allowing the electron(s) to flow more freely within the semiconductor matrix or lattice.
The “free flowing” electrons knocked loose by the photons can “en masse” produce an electric field that repels or otherwise forces the free electrons to flow in a certain direction, which when “collected,” can produce a voltage and/or current. Metal contacts or other conductive structures can be placed on the opposing sides (i.e., top and bottom) of a PV cell to provide a flowpath for the electrons, resulting in a voltage and current that can be utilized for a variety of purposes, such as for providing power to rechargeable devices.
Each PV cell has specific operating characteristics that are dependent upon the current and the voltage produced by the solar cell. Depending upon the constituent components of the cell (i.e., the lattice material, dopants, other additives and/or construction of the cell), as well as the PV cell's shape and size, the operating characteristics produced by a given cell can vary significantly. In general, a cell of a given “type” will typically produce operating characteristics with a fixed (or “assumed”) working or “nominal” voltage, a current, and indicated power calculated in watts. Assuming a cell with given operating characteristics at standard testing conditions (STC), therefore, it is possible to customize an array to provide the desired power required for a specific use. In various embodiments, PV cells can be connected together in various configurations (i.e., series, parallel and/or various combinations thereof) to form modules that provide a power output. If desired, multiple modules can be connected together to form complex PV arrays of different sizes and/or power outputs. Depending upon desired power requirements, the modules of an array can form a component part of a PV system, where the PV system is utilized to provide power for a variety of applications, such as recharging and/or powering devices. In general, traditional PV systems also include a wide variety of ancillary systems, such as auxiliary electrical connections, integrated mounting hardware, power-conditioning equipment, temperature regulating equipment, computers, circuits, inverters, charger controllers, and storage batteries that store solar energy for use when the sun is not shining and/or insufficient power is being generated to meet load requirements.
The power generated by PV arrays and equipment is generally more expensive than equivalent power from other sources due to the inclusion of auxiliary electrical systems. Moreover, the numerous ancillary systems and/or components necessary for use with typical PV systems impart significant additional disadvantages to such systems, which can include: (1) the ancillary equipment requires power and generates additional inefficiencies, which can reduce/de-rate and/or otherwise impact the useful power generated by the system for use by the consumer; (2) ancillary equipment can be expensive, and typically adds significant expense to the overall cost of the PV system; (3) ancillary equipment typically converts or generates a maximum output power for the system, which may have to be reconverted by subsequent equipment to be useful for a particular device (i.e., the PV power output is not “tailored or matched exactly” to the intended device); (4) depending upon the type of PV system, failed or malfunctioning ancillary components may be impossible to replace without dissembling or ruining the device, or their removal and/or replacement may require specialized equipment and/or technical training; (5) the ancillary equipment may not be available in rural or remote locations, or may be available at only a prohibitive cost; and (6) the operation of such ancillary equipment or associated electronics may be unreliable for a given desired application.
As a result, there exists a need for a simple, ruggedized, portable PV system that is tailored to power the intended device or portable device directly or recharge the batteries of intended devices or portable devices, such as a mobile phone, lights, radios, laptops, tablets, iPads, iPhones, cell phones, smart phones, digital cameras, personal data assistants, MP3 players, storage batteries or other devices, and that reduces or eliminates the need for additional ancillary equipment and/or electronics.