Showing papers on "Grid-connected photovoltaic power system published in 1980"

Solar power system requiring no active control device

Abstract: A solar power system has a photovoltaic array having a locus of peak power points for various insolation levels, a voltage-dependent variable resistance load such as a water electrolysis unit electrically connected to the array, and a demand-dependent variable resistance load such as a DC to AC inverter connected in parallel with the electrolysis unit. The electrolysis unit or other voltage-dependent variable resistance load has a voltage-current characteristic in which the operating point is displaced from the array's peak power point for most insolation levels. The characteristic is displaced towards higher voltage-lower current operating points. The inverter may move the operating point of the photovoltaic array toward its peak power point when the load requires power. The system may be designed so that the array operates within about 5 percent of its peak power point over a wide range of inverter power demands. A fuel cell may be connected in parallel with the array to provide power to the inverter at low insolation levels, at night or in low sunlight. The fuel cell may use the hydrogen produced by the electrolysis unit for fuel. The total photovoltaic power made available by the system of this invention is generally greater than 95 percent and often greater than 98 percent of the maximum power which the photovoltaic array may produce for many insolation levels.

Simulation of the performance of a 100-kW-peak photovoltaic system

Abstract: MIT Lincoln Laboratory designed and is currently constructing a 100-kW-peak photovoltaic (PV) power system for the Natural Bridges National Monument (NBNM) NBNM is located in a remote part of southeastern Utah and the PV system will operate in a stand-alone mode (ie, no tie-in with a utility grid) Backup power will be supplied by an existing diesel-powered generator The PV system and its individual components are being analyzed through the use of a computer simulation Useful relationships have been found for system operating characteristics, array output, generator power usage, generator control strategy, storage losses and battery charge/discharge cycles The system operating voltage can be set to extract maximum power from the array during the winter when that power is needed most The generator operating strategy can be designed to minimize adverse effects on the batteries Losses due to storage are offset by surplus array energy and by generator power

Residential solar-photovoltaic power systems: the need for battery storage

Abstract: Benefits of battery storage used in conjunction with residential solar photovoltaic (PV) power systems were evaluated for a representative set of utility service areas. The PV systems were assumed capable of exporting excess power to the utility grid, and the batteries sited at the substation level were operated as a form of load-leveling utility storage. A cost-allocation model, SIMSTOR, was employed to determine utility fuel and capital cost savings resulting from the addition of batteries as a function of PV system penetration level. These benefits were compared with the savings of batteries used alone without introduction of the PV systems. Battery storage capacities and discharge rates were varied to determine the battery configurations that maximize net utility savings as a function of battery costs. Installed (rated) PV device capacities up to 20 percent of the generation peak load in each service area were considered. Findings indicate that batteries and PV systems are complementary rather than competing technologies, when attached to the electric supply grid. The utility benefits of the PV systems are primarily fuel savings, while those of the battery are primarily due to savings in utility capacity. The economic rationale for batteries does not change significantly as the penetrationmore » level for the PV systems increases. In some of the service areas, the addition of the PV systems tended to sharpen rather than flatten the peaks in the utility's load curves, with the magnitude of the effect becoming more pronounced at the higher PV system penetration levels. As a result of these load shape changes, batteries with higher discharge rates and larger storage capacities were favored.« less

Hybrid photovoltaic/thermal systems with a solar-assisted heat pump

Abstract: An outline of possibilities for effective use of PV/T collectors with a Solar Assisted Heat Pump is given. A quantitative analysis of the performance and cost of the various configurations as a function of regional climates, using up-to-date results from solar heat pump and PV/T collector studies, will be required for more definitive assessment; and it is recommended that these be undertaken in the PV/T Program. Particular attention should be paid to development of high performance PV/T collectors, matching of heat pump electrical system to PV array and power conditioning characteristics, and optimization of storage options for cost effectiveness and utility impact.

A central receiver solar power system for remote locations

Abstract: A solar power plant has been designed to provide electrical and/or thermal power for locations isolated from a utility grid. Up to 1,000 KW electric or 4,000 KW thermal or various combinations can be provided. Applications can include domestic, agricultural, and light industrial use with different amounts of electricity and thermal power available upon demand. A small central receiver is employed for solar energy collection and steam is used as the working fluid. Modular thermal storage matches various specific applications without changing the balance of the system. All equipment is designed for easy transportability and minimum on-site assembly. Attractive economics are attained through: (1) use of a common, prefabricated receiver/tower assembly for all installations, (2) common usage of heliostats under development for the United States Large Central Receiver Thermal Electric Program, (3) simplicity in system design and maximum use of commercial equipment, and (4) skill requirements and costs for operations and maintenance approximating those of a similar size oil-fired plant.

Computer simulation of solar electric generating plants in a utility grid

Abstract: Solar electric power systems have the potential to supply power for industrial, commercial, institutional, and utility applications and to reduce consumption of non-renewable fossil fuels. However, widespread utilization of solar electric technologies in the United States will require that the solar systems be operated in parallel with, or as supplements to, the existing utility grid. For such systems, assumptions regarding future electric energy costs and rate structures have a major impact on solar system design and economics. Thus, in order to fully assess the economic worth of solar electric systems, it is necessary to evaluate their impacts on utility generation characteristics and to determine solar electric system design and cost relations within the context of the overall utility/solar system interaction.

Computer simulation of the operations of utility grid connected photovoltaic power plants

Abstract: In order to evaluate the commercial viability of photovoltaic power systems it is necessary to have reliable estimates and descriptions of the supply of electricity generated by the solar technology, the demand for that electricity, and the market application A methodology which produces information on performance, cost, and value components of utility grid connected photovoltaic power plants has been developed to assist in these evaluations (References 1, 2) This report describes that analytical model and presents an application to a utility grid connected central power system with a range of operations alternatives