A grid-connected Photovoltaic system is feeding the photovoltaic electricity generated into the electricity grid. In Figure 4, the electricity generated by a Photovolatic module is in the form of a direct current (DC). The electricity then needs to be converted to an alternating current (AC) for which an Inverter is required.
The new feed-in tariff in Croatia put in place energy supplier HEP rewards each kWh produced by your grid-connected PV system, guaranteed for the duration of 12 years.
Figure 4: Example of an On-grid PV system
The maximum yield of a Photovoltaic system depends on a multitude of parameters such as the:
technology selected (Photovoltaic modules, inverter, cables etc. = degree of efficiency)
geographic location = in Croatia 40 - 50% more sun radiation than in central Europe
clear and unobstructed access to the sun radiation (free from shading)
alignment of your Photovoltaic system (see Figure 5) = ideally a south facing roof
flat, tilted roof top (new or remodelled home) or fixed on the ground
inclination of the rooftop = ideally 15° - 50° degrees (see right of Fig. 5)
availability of space to place the Photovoltaic modules = calculate 10 square meters per kW peak installed
basement for placing the inverter (can also be externally installed)
Figure 5: Percentage of maximum yield in dependence of module alignment
Sometimes also referred to as “stand-alone” or “independent” Photovoltaic systems usually contain a battery in order to store the energy. Besides the most frequently used acid type of batteries, new high quality batteries are available with life times up to 15 years. Figure 6 shows that the battery is connected to a Photovoltaic module via a charge controller, which protects the battery from over or discharge. Off-grid PV systems with batteries can be designed to power equipment that requires DC or AC electricity. In addition, off-grid PV systems can also be designed to run with or without battery backup (i.e. calculators, parking lights, construction signs etc.)
They are particularly suitable in remote locations. In this regard it is often more cost-effective to install an off grid Photovoltaic system proves than extending the power lines.
Off-grid Photovoltaic system can be used for a wide range of applications such as:
Residential and Commercial: Lighting and other DC appliances such as Vs, radios, refrigerators, air conditioning, machinery and others
Agriculture: Pumping systems to supply water for land irrigation or livestock watering
Mobile and Recreational: Battery charging stations: recreational vehicles and boats
Figure 6: Example of an Off-grid PV system
For dimensioning purposes, a 3 kWp off-grid PV system, with a module area of roughly 28 square metres, would produce enough electricity to meet the power demand of an four person household in Southern Europe.
Photovoltaic is safe, clean and requires virtually no maintenance
Photovoltaic systems can easily be installed on flat or tilted rooftops, as part of the building's shell or fixed on the ground
The maturity of technology assures long shelf life of PV modules (>20 years)
Photovoltaic is supported by government funding with a guaranteed feed in tariff for 12 years
Grid-connected Photovoltaic is a long term investment generating attractive earnings in sunny-blessed Croatia
Off-grid Photovoltaic systems provide leverage for remote residential and commercial clients to be power self-sufficient – to be less vulnerable to energy crisis
