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.