PHOTOVOLTAICS - Knowledge base

Renewable energy sources (wind energy, solar energy, hydropower, geothermal energy, biomass and biofuels) are an alternative to fossil fuels and contribute to reducing greenhouse gas emissions, diversification of energy supply and reducing dependence on uncertain and volatile markets of fossil fuels (especially oil and gas). The EU is a leader in renewable technologies and owner of 40% of all patents in the area of ​​renewable energy in the world. In 2012 almost half (44%) of the global electric power from renewable energy sources was located in EU (excluding hydropower). The EU's renewable energy sector currently employs approx. 1.2 million people. EU legislation on the promotion of renewable energy sources has changed considerably in recent years. Also there are ongoing discussions on the future policy framework for the period after 2020.

Solar panel - otherwise known as a photovoltaic module or PV panel is an electrical device, where in transform solar radiation to DC voltage. A solar panel consists of cells, small silicon plates in which there is the photovoltaic effect. A single panel is connected to the other panels which together form a photovoltaic system. The panels are mounted on a special support structure, either on the roof or on the ground green. There is also the possibility of installation on the facade of the building, or use them instead of windows (BIPV). Power of each PV panel is given as a power that reaches the so-called STC conditions (appropriate temperature, light, pressure, etc.). The efficiency of the modules, reaches from 14 to 16% in STC conditions (record in laboratory conditions obtained by JA Solar was 20%). Standard solar panels have a rated power of 100 to 320 watts. PV panels produce direct current , so an essential element of the PV systems is the inverter (inverter PV), whose description we can find below.

Inverter (inverter PV) - is a device with transform DC electricity generated in the PV system to AC current with the same parameters as this from power plant. Inverters are specially designed to work with PV installations and include a number of protections, system protection against work insular. Inverters can be categorized as follows:

- Without transformer (most commonly used),

- Transformer with galvanic isolation (used for thin-film modules),

- Island (dedicated for the installation of off-grid, which is not connected to an external network).

It is also worth mentioning the MPPT trackers that have a large impact on the performance of PV installations in case of shading. MPPT (Maximum Power Point Tracking). Number of MPPT trackers in the inverter can increase yields of PV installation for about 20%. Most currently manufactured inverter has at least one MPPT system. MPPT technology is used to track the maximum power point of the PV module, looking for the highest voltage in the panels. A system of two MPPT tracekrów use when the number of modules in the strings are different or the installation is located on two roof slopes.

On-grid installation - it is a PV installation, which is connected to the network electricity distributor. In this case, the electrical energy from PV is consumed in the first place to cover the needs of their own particular object, and then returned to the grid OSD.

Off-grid installation - a PV installation, which is not connected to the network electricity distributor. In this case, the electricity that is not used to cover the needs of their own object (there are surplus electricity produced) is accumulated in special batteries. Electricity from the battery is used at the time of consumption of electricity, when the PV system is not working (eg. Evening).

The amendment to the Energy Law "Mały Trójpak" - the Act of 26 July 2013, which introduced a number of changes in relation to renewable energy sources in our country. It is part of a larger project RES called so "Duży Trójpak". The amendment to the law is a consequence of the imposition by the EU relevant standards (Directive 2009/28 / EC), on the use of RES Poland has obligate to a 20% share of RES in 2020. Energy legislation "Mały Trójpakt" and consequently "Duży Trójpak"  to facilitate the development of renewable energy sources in Poland.