Talking about how to design off-grid photovoltaic system solar street light-litelsolar production plant

01Basic data that must be understood before installation First of all, it is necessary to understand the user's voltage phase, is it single-phase AC 220V, or three-phase AC 380V? This determines the output characteristics of the inverter; followed by the type of load, is it an inductive load or a resistive load? This determines the load power and output waveform of the inverter. The third is the full load running time of the load, that is, how many degrees of electricity do we need per day on average? If it is a photovoltaic grid-connected power station, since there is no energy storage device, it is only necessary to configure a reasonable power of photovoltaic modules; if it is a photovoltaic off-grid power generation system, the capacity of the battery must also be calculated, including when there is no photovoltaic power generation condition in continuous rainy days. The self-reserve power of the system. 02 Case of photovoltaic off-grid power generation We take the photovoltaic off-grid power station of a small lake farmer as an example. Due to long-distance power supply, the cost is high, and the power loss and voltage loss of the transmission wire are large, and the typhoon hits, resulting in unstable power consumption, frequent unexpected power outages, affecting production and domestic power consumption. For this reason, it is proposed to use photovoltaic off-grid power generation. The solar radiation intensity is high during the day. The photovoltaic power generation directly inverts the output, the power supply works, and charges the battery at the same time, and the battery inverts the output at night. The voltage is AC220V 50Hz, and the electrical equipment mainly includes: fish pond oxygen pump (300W) 10 TVs + satellite receiver (200W) 1 set of rice cooker (750W) 1 induction cooker (2000W) 1 refrigerator (100W) 1 The lighting (100W) load is not used at the same time. The oxygen pump works when the sun is shining during the day and does not work at night. The power of other electrical appliances is about 3000W, and the daily electricity consumption is about 10 degrees. Due to the sufficient light on the lake, the rainy days are not considered. Self-reserve power. 03Photovoltaic inverter According to the above data provided by the user, in the design of this system, SAKO Sanke? Off-grid photovoltaic inverter integrated machine is selected, the power is 48V 6KVA, the power factor is 0.9, the inverter conversion efficiency> 88%, the actual The load power can reach 5000W, which can meet the output power requirements of the user's electrical equipment. 04 Battery capacity The energy storage device used in this photovoltaic off-grid power generation system is a commonly used lead-acid battery, which has large capacity and high cost performance. The reserve power of the battery is 10KWh. Since the DC input voltage of the photovoltaic inverter is DC48V, the theoretical capacity of the battery is calculated: 10000VAh/48Vu003d208Ah According to the relevant technical standards of the battery, the discharge rate of the battery is more economical and reasonable at 0.5C2 , which can ensure the cycle charge and discharge times of the battery and effectively prolong the service life. Due to the sufficient sunshine in the lake, the photovoltaic output is directly inverted during the day, and there is no need to go through the repeated discharge procedure of the battery. At night, the electrical power consumption is small and the discharge time is short. Therefore, the battery discharge rate is appropriately increased to 0.6C2 in the design of this scheme. Actual capacity calculation: 208Ah/0.6u003d347Ah The value here is 400Ah, that is, the total capacity is: The specification of 48V 400Ah lead-acid battery is 12V 200Ah/pc, the connection method is 4 series and 4 parallel, and a total of 8 batteries are required. 05 Photovoltaic module power After the configuration capacity of the battery is obtained through the above calculation, the power configuration of the photovoltaic module is calculated. The geographical location of the lake has high solar radiation intensity, and the effective sunshine time is as long as 6 hours. Using polycrystalline silicon photovoltaic modules, the photoelectric conversion efficiency reaches 16%, which meets the standards stipulated by the National Energy Administration. The calculation formula of photovoltaic power generation is: system power generation u003d photovoltaic module power × sunshine time × comprehensive coefficient. The comprehensive coefficient refers to the loss coefficient caused by factors such as temperature change, line loss, controller (or inverter) conversion efficiency, generally 0.5-0.7, this time 0.6, therefore, photovoltaic module power calculation: 48V×400Ah /(6h×0.6)u003d5333W The specification of the module is 36V 275W, the size is 1900×980×45mm, and the area is about 2 square meters. The connection method is that every 2 pieces (72V) are connected in series as a group, and then 10 strings are connected in parallel, a total of 20 photovoltaic modules are required, the total power is 72V 5500W, and the photovoltaic module array area is 40 square meters.