Each newly installed photovoltaic array shall pass post-construction inspection. It is intended to check that the panel chains are connected correctly and that the panels themselves are not damaged, and to eliminate potential manufacturing errors [1].
The installation documentation should include its schematic diagram, dates of commissioning and inspection, technical data of the panels and inverters, power rating (the maximum power at which the equipment can operate for a long time without suffering damage with minimum distortion), and details of the installing company. The diagram should give the number of panels and their types, as well as:

• the number of strings together with the number of panels that make up the string,
• inverters with assignments to the strings,
• type and cross section of wires,
• connection locations,
• protection information,
• DC switch (parameters, location, protection elements),
• grounding system,
• charging regulator (if any),
• energy storage tank,
• MPT tracker (if not integrated in the inverter).

In addition, data sheets of the equipment should be attached to the documentation. An important part of the documentation are the instructions on how to behave in case of a breakdown or a random event (e.g. fire).
The first step is to perform a visual inspection of the installation (procedures included in the provisions of the PN-EN 62446-1 standard), while the basis for the visual inspection of the installation are the guidelines of the PN-HD 60364-6 standard.
Based on the documentation of the photovoltaic installation, it should be checked whether the assumed operating parameters of the panels are actually achieved. The test should be conducted in accordance with the PN-EN 62446 standard.

The tests (according to PN-HD 60364-6) are divided into two categories. They are presented in Fig. 1 [2].

Category I includes tests which should be performed for all installations. The AC side of the installation should be tested first (in accordance with PN-HD 60364-6), followed by the DC side. If category I tests are passed, category II tests may be performed. The basic test methods in this category are testing the temperature distribution of individual panels using a thermal imaging camera and analysis of current-voltage characteristics.
If category I or II tests reveal any irregularities, additional tests are performed, e.g. voltage-to-ground test, barrier diode test, wet insulation resistance measurement and shading assessment.
Upon completion of the tests, a report shall be prepared and submitted to the investor, containing the results of all tests carried out, the characteristics and the date of the next inspection. This report is the basis for warranty and compensation claims [3].