The inverter is the main point of conversion and control for the energy generated, ensuring safe grid connection, production monitoring and effective use of the energy consumed at the time of generation.
For installers: Check grid compatibility, protection requirements, export-limitation capability and compatibility with battery storage systems.
Yes. An inverter with an input for a smart meter or energy controller is required, or alternatively a control system that limits the inverter’s output power to prevent energy from being exported to the grid. This usually operates in conjunction with a smart meter or energy controller.
For installers: Confirm that the inverter supports export limitation or zero-export operation and is compatible with the appropriate meter before making the final selection.
Yes. A change of inverter type or manufacturer is accepted provided that written notification is submitted to HEDNO, together with the relevant technical manuals and certificates, and that the new total installed capacity in kWp does not differ by more than 3% from the capacity originally declared. Source: HEDNO
For installers: Select equipment with readily available datasheets and certificates to ensure that notification of the change does not delay the project.
Oversizing means installing a higher solar panel capacity (DC) than the inverter’s nominal AC output capacity. For example, a 13.5 kWp solar array connected to a 10 kW AC inverter, with a DC/AC ratio of 1.35. This increases energy production during morning and afternoon hours and under cloudy conditions, while causing only limited clipping during peak-production hours.
For installers: DC/AC ratios of approximately 1.10 to 1.35 are commonly acceptable without significant energy losses. Always check the maximum permitted DC input capacity of the specific inverter.
Each MPPT (Maximum Power Point Tracker) independently optimises one or more strings. A separate MPPT is required when strings have different orientations, tilt angles, shading conditions or numbers of panels. Otherwise, the lower-performing string may limit the performance of the entire group.
For installers: On dual-pitch roofs with two inclined surfaces, such as east- and west-facing roof sections, select an inverter with at least two independent MPPTs. For roofs with three or four differently oriented surfaces, select an inverter with at least three independent MPPTs, depending on the array configuration.
The combined open-circuit voltage (Voc) of the panels in a string, adjusted for the lowest expected temperature, must not exceed the inverter’s maximum input voltage. Similarly, the string’s short-circuit current (Isc) must remain within the inverter’s permitted input-current limits.
For installers: Use the inverter manufacturer’s string-sizing tool with the lowest historical temperature recorded in the area rather than relying solely on standard test conditions (STC).
A string inverter serves one or more groups of panels and is generally used in small and medium-sized installations. A central inverter is used in large solar plants, where multiple strings are connected to a single central inverter. A hybrid inverter incorporates battery-management functionality alongside grid-connected operation.
For installers: Where battery storage may be added in the future, consider a hybrid-ready solution from the outset rather than upgrading the system at a later stage.
The IP rating indicates the inverter’s level of protection against dust and moisture. For example, an IP65 rating provides complete protection against dust and protection against water jets. It determines whether the inverter can be installed outdoors without additional protective housing.
For installers: For outdoor installation, select an inverter with a rating of at least IP65 and protect it from direct solar radiation to help extend its service life.