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My PV project: frequently asked questions

Installation and maintenance of PV systems

  1. What technical knowledge is needed to install and maintain PV modules?

    In order to install PV systems, sound knowledge of electricity is required, especially with regard to dimensioning and protection. It is also necessary to assess the static requirements of the roof and the mounting systems. In some countries, in order to connect to the grid, the electrical contractor or installer needs to be certified.

    EU member states must ensure a certification scheme for PV installers is in place by the end of 2012.

  2. How do I label DC cables?

    Regulations on labelling may be different in each country, but usually positive cables are labelled red and negative cables black.

  3. What inverter can I use?

    First, the DC input range of the inverter should match the output of the PV array. With Maximum Power Point Tracking (MPPT), the inverter adjusts the tension and current of a string of solar PV modules in order to obtain the maximum possible power under certain circumstances. An inverter can have multiple inputs for various strings, each with their own MPPT.

    Different types of inverters exist for off-grid and grid-connected PV systems. Grid-connected inverters use the frequency and voltage of the grid as a standard for their AC output, and they are required to shut off in case of a power failure of the grid. This is called anti-islanding protection. Usually the relevant grid operator defines the requirements for inverters for grid-connected systems.

    Off-grid inverters do not interfere with the grid in any way and do not need anti-islanding protection. Many off-grid inverters incorporate a battery charger to charge the batteries from an AC source such as a generator.

    For off-grid and grid-connected systems, micro-inverters are becoming more and more common. A micro-inverter is an inverter that’s integrated on the back of a solar panel, transforming the DC of just that one panel to AC. Micro-inverters are mostly used in small systems.

  4. What type of DC cables is acceptable?

    DC cables should always be sized according to their expected load. The cables should have fire-resistant insulation, and cables exposed to weather influences should be protected accordingly to avoid corrosion of insulation material.

  5. What safety regulations do I need to take into account?

    The safety regulations for solar PV power supply systems are laid down in the International Standard IEC 60634-7-712. PV systems need to be earthed, protected from electrical shock, overload, short circuit, fire, etc. The safety regulations are very similar to the regulations for other electrical installations.

  6. Can I import panels from China?

    Regardless in which country your solar panels are produced, solar panel defects occur on a regular basis. The payback time on solar systems is based, besides FiT’s and irradiation, on the initial power output, power degradation and the lifetime of the PV module. Needless to say that solar system installers and end-user need to be entirely assured about the quality of the solar panels purchased.

    When reviewing a panel manufacturer, the most important step is to determine if the manufacturer is producing solar panels according to the industry standards. This can easily be found out by requesting the common PV product certifications. After receiving the certifications, verify the authenticity of the PV certificate on-line at for instance TÜV Rheinland.

    Certifications on your solar panels provide the standards for the profitability and security of your investment. Except for BIPV solar modules, all standard solar panels should be certified. Common solar panel (PV) certifications are IEC 61215 / EN 61215 IEC 61215 Ed. 2, IEC61646, IEC 61730 / EN 61730, IEC 60364-4-41, IEC 62108 and IEC 61701.

  7. How can I guarantee the system to work properly?

    Most panels have a warranted output of 80% after 25 years, although other components such as inverters usually have a shorter guarantee period. The proper functioning and production of a PV system can only be guaranteed if maintained properly.

  8. How can I recycle the panels after their lifetime?

    In December 2011, the Waste Electrical and Electronic Equipment Directive (WEEE) was recast to include the PV panels. Producers will have the obligation to collect and recycle end-of-life PV panels.

    A network of collection points is already in place and you can find the nearest collection point at