Photovoltaic inverter capacitor selection requirements

How reliable are DC-link capacitors in grid connected photovoltaic systems?

Methods: Dc-link capacitors are considered as one of the sensitive parts of the grid connected photovoltaic systems and needs effort to design a reliable and optimal size capacitor as its reliability is concerned with the overall system reliability.

How much CV rating do I need for a three-phase inverter?

For three-phase inverters at any DC bus voltage, for films and electrolytics, respectively, a rule of thumb is that about 5 and 50 millicoulombs of capacitor nameplate CV rating will be required per amp of ripple current.

Can a PV inverter provide voltage regulation?

A PV inverter or the power conditioning systems of storage within a SEGIS could provide voltage regulation by sourcing or sinking reactive power. The literature search and utility engineer survey both indicated that this is a highly desirable feature for the SEGIS.

What voltage should a capacitor be rated for?

In general, the DC voltage rating of the capacitor should be rated based on the average maximum bus voltage x 1.1 (factor of safety) . E.g. if your 100% SOC battery voltage is 400V, the voltage rating of the capacitor should be 450V or higher.

What is a good voltage rating for a film capacitor?

E.g. if your 100% SOC battery voltage is 400V, the voltage rating of the capacitor should be 450V or higher. The factor of safety can be relatively low for the voltage rating because film capacitors can withstand a DC potential of 1.3 x rated voltage for one minute without damage or breakdown.

Can PV inverters fold back power production under high voltage?

Program PV inverters to fold back power production under high voltage. This approach has been investigated in Japan, and though it can reduce voltage rise, it is undesirable because it requires the PV array to be operated off its MPP, thus decreasing PV system efficiency and energy production.