When the solar panel system is grid-connected for electricity power generation, to achieve maximum power efficiency, the solar panel array must implement Maximum Power Point Tracking (MPPT) control. This allows the solar panel array to achieve maximum power output under different sunlight conditions. When designing the on-grid system, for the series of solar panels in series, the following points should be considered:
1) The specifications, number of series connections, and installation angles of the solar panels connected to the same inverter should be consistent.
2) The temperature coefficients of the solar panel’s maximum power voltage (Vmp) and open-circuit voltage (Voc) should be taken into account. The Vmp of the series-connected PV array should be within the MPPT range of the inverter, and the Voc should be lower than the maximum input voltage of the inverter.
Generally, the DC input voltage range of an inverter is fixed. The recommended maximum DC input voltage for a grid-connected PV inverter is 1100V, with an MPPT range of 200V to 1000V. When selecting the number of series-connected modules, two aspects must be considered: first, the high limit of the open-circuit voltage must be less than the maximum withstand DC voltage of the inverter; second, the low limit of the rated operating voltage must not be less than the minimum value of the inverter’s MPPT range.
Given these conditions, for PV modules, the number of series-connected solar modules can not exceed 21 modules per string. At a standard temperature of 25°C, for the 540W mono-facial solar panel as an example, the open-circuit voltage would be 49.6V × 20 series = 992V < 1100V, and the maximum power operating voltage would be 41.64V × 20 = 832.8V< 1000V, which meets the inverter’s requirements.
HBOWA is a professional manufacturer and supplier of solar panels, solar lithium batteries, and inverters, provides one-stop solar power systems designing and configuring for solar panel system installers, distributors, and contractors all around the world. If you have any concerns or questions about the solar systems or components, feel free to contact us at any time, we are always here at your service.
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