1. The photovoltaic cell is a high-resistance current source, and the battery is a low-resistance voltage source. This directly explains that we can short-circuit components, but never short-circuit batteries.
2. When the battery is covered, it becomes an objective large resistance. If it is not drained, it will quickly heat up. This is also the underlying principle of component and bypass diode activated switching.
3. The difference between STC (standard test condition, that is, standard test condition) and NOCT (Nomina lOperating Cell Temperature, solar cell nominal operating temperature), in addition to the numerical difference in several established parameters, NOCT introduces a wind speed of 1m/s The purpose of the parameter is to better match the output power of the component during actual work.
4. The 25 degrees Celsius defined by the STC standard state of the component is the operating temperature of the component rather than the ambient temperature. So when you calculate the effect of temperature on the minimum operating voltage, you need to add an additional 25 degrees to the temperature of the battery panel at room temperature. However, when calculating the effect of temperature on the maximum open circuit voltage, it is not possible to add a working temperature of 25 degrees. This 25 degrees, for the calculation of projects above 3kW, is a very considerable error.
5. Remind that components of the same size and the same material (single crystal / polycrystalline) with the same rated power, if the conversion efficiency is not the same, it is deceiving. This is also a rule, with no exceptions.
6. The working voltage of the component's maximum power point and the component's open-circuit voltage have a constant relationship of 0.8, which is very close. This relationship is very important and convenient when initially estimating the rationality of the inverter and system structure. At the same time, it is of great significance to the algorithm design of MPPT.
7. On cloudy or drizzly days without the sun, the output power of the system is very small. In fact, the open circuit voltage or working voltage of Amerisolar components is still very high, even at full load! Many installers in Australia who were replacing inverters indoors on cloudy days were electrocuted. Keep in mind that on a cloudy day, the component may not output power, but it does not mean it is dead. This is a common sense that is often overlooked.
8. If the number of components in the east-west facing system is the same, it can be connected in parallel, and there is no serious voltage dislocation. Basically, as long as the light intensity is above 50W/m2, the component can work and output voltage. This explains the phenomenon that the inverter starts early, but the real output power lags behind for a period of time.