Rooftop photovoltaics are divided into two categories: household and industrial and commercial roofs. The household photovoltaic subsidy is stable and the investment income is high. It has the best and most stable policy support in all countries in the world. It is the most direct and extensive support for photovoltaics in various countries from the application of science popularization; industrial and commercial roof owners can not only save a lot of electricity, but also Can do green public welfare publicity.
Before conducting a detailed site survey, owners can consider the following parameters:
01Shadow Test
Shadow test: Photovoltaic power generation relies on sunlight, what is the lighting resource of your own roof, and whether the orientation and slope are conducive to the maximum irradiance. When installing photovoltaics, the photovoltaic panels should face south as much as possible. Roofs must be checked for shade from trees or adjacent buildings, etc., especially from the south. An open roof with no surrounding shade is ideal for photovoltaic installations. If there is shadow on the roof, a detailed analysis of the timing and direction of sunlight by an expert is required to estimate the energy received by the roof.
02 Roof type
Roof type: The bearing capacity of the roof should be checked. Photovoltaic panels weigh approximately 15kg per square meter, this weight varies by technology and type of construction. What material is your roof made of, can it bear weight, and can it withstand construction? Is it a plane or a slope? Cement roof or tile house, or color steel tile? Are you considering making it into a sun room, etc.?
03 Dimensions of the solar system
The size of the solar system: The size of the solar system depends on the roof area available for the installation of modules. This can be calculated by dividing the usable area by each component area and multiplying by the panel's rated output. It is estimated that 70% of the roof area can be used for module installation. Some solar panels on the market can use up to 90% of the roof area, but the cost is much higher. As a rule of thumb, a solar system with a capacity of 1 kW requires an area of 10 square meters.
Solar system size = module rated output * (roof area / each panel area) * 70%
04 System output
System output (annual power generation): Each module has a fixed output power, so the system power generation depends on the module efficiency and the on-site solar irradiance. These two factors define the capacity utility factor of a solar system at a specific location.
As a rule of thumb, a 1 kW solar system generates 1000-1500 kWh of electricity per year, and the amount of power generation varies with the installation location, local climate, and geographic location.
05 Pricing of Solar System
Pricing of solar system: A typical rooftop solar system, without energy storage and without grid connection, is also related to scale, location, installation difficulty, etc. System prices over 20KW will be cheaper.
06 Local PV Installation Incentive Policies
In addition to the state subsidy, there may also be some subsidy support in various places.
07 Local climatic conditions
Solar power, of course, requires sunlight. The local climatic conditions in which you are located affect the power generation income, including: the annual irradiance belongs to several types of regions, the ratio of sunny/cloudy days, how the local air pollution is, whether the local dust is serious, whether the local rain is regular, and the rain is relatively normal. How helpful is cleaning and maintenance, etc.
In short, to have a good return on investment, you need to consider these factors comprehensively before investing. The quality of the system installation should also be considered, and the fire should not be outweighed by the quality failure.