Solar full-spectrum concentrating utilization system and method based on photovoltaic reflecting plate

Abstract

A solar concentrating utilization system comprises a plurality of photovoltaic reflecting plates which are arranged in a specific shape and / or arrangement to form a concentrating device, and each photovoltaic reflecting plate is used for absorbing part of sunlight for photovoltaic power generation and reflecting other sunlight which is not absorbed by the photovoltaic reflecting plate or totally reflecting the sunlight; and a concentrating spectrum utilization device which is arranged at or near the focus of the concentrating device formed by the plurality of photovoltaic reflecting plates andis used for utilizing the sunlight reflected by the photovoltaic reflecting plates. According to the system, the solar spectrum suitable for being used by the photovoltaic cell in the solar spectrumis used by the photovoltaic cell, and the sunlight of the residual solar spectrum is gathered to the concentrated spectrum utilization device, so that the full-spectrum utilization of solar energy isrealized. And the energy ratio of photovoltaics to condensation can be adjusted, optimal matching is carried out according to a utilization method, and the overall utilization efficiency of solar energy is improved.

Description

technical field [0001] The invention relates to the technical field of solar energy utilization, in particular to a solar energy full-spectrum concentrating utilization system and method based on a photovoltaic reflector. Background technique [0002] Solar photovoltaic utilization technology is a technology that uses the photovoltaic effect to convert sunlight into electrical energy. Affected by the principle of the photovoltaic effect, photovoltaic cells can only use part of the energy of part-spectrum sunlight. Taking monocrystalline silicon photovoltaic cells as an example, it can only partially convert sunlight with a wavelength shorter than 1100nm into electrical energy, and the photoelectric conversion efficiency is lower for sunlight with a shorter wavelength, and most of the unused energy is consumed Converted to heat energy wasted to the environment. At present, the power generation efficiency of commercial photovoltaic cells is mostly below 25%, which means that...

AI Technical Summary

Problems solved by technology

Since the photothermal conversion process can approximately use the full spectrum of sunlight, solar thermal power generation technology does not face the problem of not being able to use the full spectrum of solar energy

However, solar thermal power generation technology faces the following problems: ① The grade of sunlight as an energy source is relatively high, at 0.93, while the temperature of general solar heat collection is around 400°C (point focusing can be at 800°C), and the grade of this heat energy is only 0.55. Therefore, the irreversible loss is serious in the process of solar photothermal conversion, and a large amount of available energy is wasted in this process; ②The temperature of the heat collection process is high, and there is obvious loss of radiation and heat dissipation; ③There are also many kinds of energy in the subsequent conversion process of thermal energy to electrical energy Loss, the available energy obtained by the heat collection process is further lost

The combined effect of three factors makes the efficiency of solar thermal power generation only about 15%.

[0011] Hydrogen production by solar photovoltaic electrolysis of water has the advantages of mature technology, simple equipment, no pollution, high purity hydrogen and low impurity content, and is suitable for various occasions. The hydrogen production cost of the technology is high, and generally requires noble metal catalysts

When the source of electric energy is not considered, the efficiency of electrolytic water technology can reach 90%, but considering the power generation efficiency of photovoltaic cells, the energy utilization efficiency of solar photovoltaic electrolytic water electrolysis for hydrogen production is actually less than 30%.

[0019] 1. The single solar energy utilization method faces the problems of low efficiency and high cost

Solar photovoltaic power generation technology cannot use full-spectrum sunlight, and the power generation efficiency is below 25%. More than 70% of solar energy is converted into low-temperature heat energy and wasted into the environment; Moreover, the loss of radiation and heat dissipation is large, resulting in a large amount of available energy in solar energy being wasted in the process, and part of the available energy is wasted in the further conversion process from thermal energy to electrical energy, and finally the efficiency of solar thermal power generation is generally below 15%.

[0020] 2. Existing photovoltaic power generation methods and systems, or lack of tracking devices lead to large cosine loss and reduced power generation, or equipped with tracking devices increases construction and operating costs

[0021] 3. Existing photovoltaic cells have higher reflectance in the solar spectrum range that can be converted into electrical energy, and lower reflectance in the solar spectrum range that cannot be converted into electrical energy, which reduces the power generation efficiency of photovoltaic cells and increases the operating temperature. even caused a fire

[0022] 4. In the existing reflective concentrating method and system, sunlight needs to penetrate the reflector glass twice during the concentrating process, resulting in a large optical loss; in addition, during the concentrating process, the reflector needs to track the sun, so each reflector The tracking mechanism needs to be connected to the power supply, which requires a lot of cables and high investment costs

[0023] 5. Existing concentrating methods and systems cannot effectively use solar energy in rainy, cloudy and hazy weather, which reduces the system utilization rate and annual average solar energy utilization efficiency

[0024] 6. In solar photovoltaic waste heat utilization technology, the solar spectrum that cannot be converted into electrical energy by photovoltaic cells is also projected onto the surface of photovoltaic cells and converted into low-grade heat energy. In the process, most of the available energy in solar energy is wasted and low-grade The use value of heat energy is not great, and the efficiency of photovoltaic cells decreases due to temperature rise, which partially offsets the benefits of waste heat utilization

[0025] 7. In the solar frequency division photovoltaic photothermal utilization technology, additional frequency division devices need to be introduced. On the one hand, this makes the system relatively complicated and will increase the cost; on the other hand, it introduces additional losses, which will reduce the operating efficiency of the system.

The energy flux density of the long-wave beam used for the photothermal part after frequency division is reduced, which makes the solar heat collection capacity decrease when this part of the beam is used alone for thermochemical reactions or the heat collection efficiency at high temperatures is reduced, resulting in long-wavelength beams after frequency division. The solar energy utilization efficiency is low, and if the long-wave light beam is used alone for photocatalytic or photoelectrolytic reactions, because it is mainly long-wave, the photon energy is low, and it is not enough to excite the electrons in the valence band to the conduction band. The photoelectric transition effect is not good. Ideal, also leads to inefficient use of solar energy in this part

[0028] 10. Existing frequency division technology realizes spectral frequency division and energy distribution are coupled together, and its distribution ratio is often fixed, which will lead to solar energy itself There may be a mismatch between the various energy ratios allocated and the optimal energy ratios required for the chemical fuel process

The mismatch of energy on both sides will lead to energy loss in the process of converting solar energy into chemical energy, reducing the utilization efficiency of solar energy

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