What is characteristic of off-grid solar power system ?
Off-grid solar power system means that it doesn’t connect with public grid, it is individual. The conversion efficiency of solar cells is effected by its temperature, sunlight intensity and voltage float of battery, meanwhile, these three factors would fluctuate during one day, which would be effected by the spectrum of solar radiation, thickness of aerosphere, geographic position, weather and climate, surface features, etc, the solar power would have big difference among each day, each month and each year, even the total solar radiation would have a large difference among every year. The variation period of solar radiation is 24h each day in various districts of the world, the power generation of solar cells which is in some district also has 24h variation period, its discipline is the same as this district where is radiated by solar variation. Moreover, the variation of weather would effect the power generation of solar panels, it would not generate if to continue raining many days, so, the power generation of solar cells is variation.
Battery pack work under floating charge state, its voltage is variation according to the power generation of solar array and power consumption of load. The power supply of battery is also effected by environmental temperature. Solar controller is made up of electron components, its internal side also would consume power, and the performance and quality of electron components also would effect power consumption, then effect the efficiency of charging. The electricity consumption of load rely on application, which has the power consumption of fixed equipment, such as communication relay station, unmanned weather station etc, while the power consumption of some appliances is frequently variation, such as lighthouse, beacon light, Civil lighting and household electricity, etc.
Regards to off-grid solar power system, power generation from solar panels is the unique power supply, under this condition, the load can be divided daytime, night and daytime with night from one day. For those load which is used in daytime, most of them can be directly power supplied by solar panels, which can reduce wastage of battery because of changing and discharging, the system volume of solar power can be matched smaller. For those load which is fully used in night, the power of solar panels would be increased. For those load which are used in daytime and night, its system solar power is between the formers. Moreover, appliances load can be divided as load balance, seasonal load and random load from whole of year. There are a lot of factors to effect solar system working, relation is complicated, it need be analyzed according to location condition and operation state when making design an off-grid solar power system.
Solar irradiation can not be accurately confirmed after installation because of random of solar radiation, just can treat historical record of local meteorological observatory as reference. Nevertheless, the solar irradiation that meteorological observatory provide is from flat radiation, it need be calculated as irradiation from incline. In terms of ordinary solar power system, that is enough to calculate the average irradiation from incline each month, don’t have to consider instant solar irradiation. The obligation of designer is to keep the solar system having great economy and high reliability according to the environmental situation where the solar panels are in (That is geographic position, solar radiation, climate, weather, geography and surface features, etc)
Bingsolar Power, 13th, November, 2017
