According to the formula, we know that the solar altitude angle (α) is related to the geographic latitude angle (φ), the solar declination angle (δ) and the solar time angle (ω). For solar energy collection fixedly installed on the ground in a specific place For devices, only when ω=0°, φ=δ, α=90° can the local maximum solar radiation value be obtained, that is, the strongest solar radiation energy that each solar energy utilization device may collect is only It may appear at noon (ω=0°) in those areas where the latitude is exactly equal to the solar declination angle (φ) of the day. In other words, for a solar energy utilization system installed in a fixed location, the installation angle of the solar collector should be as close as possible, or equal to the local geographic latitude angle (φ), and the azimuth angle ys =0; it is possible to use the sun The angle of incidence (θ) and the angle of elevation (α) are complementary angles (∠θ+∠α=90°) to obtain the solar irradiance energy under the best local sunlight incident conditions.
In the practical application of solar energy, in order to have a relatively objective and quantitative measure of solar radiation intensity, scientists also introduced a new physical quantity called “solar constant”. The so-called solar constant (S0) refers to the average distance between the sun and the earth, that is, in April and October of each year (at this time, the deviation of the earth’s farthest distance and the closest distance are both 1.7%; the error of the received solar energy is about ±3%), the value of solar radiation intensity per unit area (ie, solar radiation flux) on the surface of the earth’s upper atmosphere perpendicular to the sun’s rays. Due to the different ages of the observations, the observation methods and measurement methods are different: the values of the solar constant (S0) in different books and data will have some differences. But it is generally believed that the solar constant S0=1353W/m2 (or 1.94Cal/cm2·min; 4871kJ/m2·h; the error is about ±1.5%). Obviously, scientists set the solar constant (S0), which is the same as setting the sun as a black body with an average surface temperature of 6000K and radiating energy with electromagnetic waves of 0.3μm ~ 3μm. It is to simplify other uncertainties. The interference factors allow us to use the same reference coefficient to calculate the area of solar collectors or photovoltaic cells that should be configured relatively accurately when doing solar system engineering design: or, in turn, pass a recognized standard Value to objectively evaluate, or compare the design schemes of different systems or the photothermal and photovoltaic conversion efficiency of the utilization device.
Because each place on the earth is located at different geographic latitudes, altitudes, and topography, not only the altitude angle (α) of the direct sun at all times changes with the seasons, day and night. And also because of the differences in the environment, climate, and ecological geomorphology of various regions, including sunshine, cloud cover, cloudy and sunny, rain and fog, humidity, dust, haze, atmospheric circulation, vegetation and other natural environmental factors, the sun in each region The distribution of resources is uneven, unstable, and even unique with local characteristics. Therefore, although we can say that the sun gives its own light and heat resources to each of our families freely and selflessly, regardless of each other’s and nobleness. But in fact, for the sunshine audience in different regions, the distribution of solar resources is not completely balanced, and there are even big differences. Therefore, it can be considered that the feasibility of using solar energy in all parts of the world cannot be generalized with the cost and price of achieving the same goal. In summary, solar energy has the characteristics of hugeness, long-term, universality, harmlessness, periodicity, discontinuity, dispersion, and dungeon particularity. Therefore, the use of solar energy must always be pragmatic, tailored to local conditions, “one matter-discussion” policy, the same system, under different urban and environmental conditions, the effect or practicality will certainly not exactly the same.
The technical core of solar energy utilization and the difficulties and key points that need to be overcome are: efficient collection of solar radiation energy, effective storage across time and space, and innovative development in the field of utilization technology, coordinated solar system engineering design and industrialized fine manufacturing according to local conditions Building installation and thoughtful and meticulous maintenance and management. In short, it can be summarized into two major categories (collection and storage), three links (collection and savings, design and manufacturing, installation and management), and five major projects (innovative development, engineering design, fine manufacturing, construction and installation, Maintenance management). Innovative development of solar radiant energy efficient collection and energy storage technology products across time and space, high-standard industrial production, and large-scale promotion and utilization in production and life around the world as the goal of the new energy industry has become today’s global development. The fastest emerging sunrise industry.
Scientists predict: With the depletion of global fossil energy resources and the unprecedented accumulation of carbon dioxide emissions, the carbon cycle of the earth’s natural environment is disrupted. The global annual emissions of nearly 4×10″t carbon dioxide and other greenhouse gases have promoted the increase in temperature. Leading to global climate anomalies. Under the severe impact of the dual factors of resources and the environment, human society will be forced to rely on the use of new technologies and new technologies for 80% of the total energy necessary for production and life by the middle of the 21st century at the latest. In-depth development of new processes, new materials and new methods, new energy and clean renewable energy for practical use.