All PV systems are in fact integrated sets of PV modules and other components, such as structure for installation (on the ground or roof), maximal power point tracker and other devices for regulation, eventual storage components (batteries, chargers...), DC/AC converters (inverters), cables, connectors, enabling the optimal supply of the electricity being produced from the PV modules (arrays, strings) to the network, AC or DC consumers.
Two most commonly encountered configurations of PV systems are:
· Systems that feed power directly into the utility grid or through network connection installation such as lines and transformers (on-grid/grid-connected PV system)
Figure 4 Typical on-grid PV system [4]
· Stand-alone systems with and without energy storage (batteries and chargers) (off-grid PV system), sometimes with generator back-up (hybrid PV system).
Figure 5 Typical off-grid PV system [4]
There are however big problems in direct Sun radiation usage in electricity production using photovoltaic system: small density of energy flow, oscillation in radiation intensity during day/month/season, dependence on climate conditions, with radiation intensity not coincident to electricity consumption.
Initially, due to the expensive battery storage and PV module materials there were high specific investment costs of photovoltaic systems compared to conventional or even non-conventional (renewable) energy technologies. Combined with small efficiency and power factor this resulted in high electricity production costs. However, high incentives in over hundred countries resulted in fast PV technology development, the fastest usage increase with over 130 GWe of installed PV capacities world-wide in 2013 [5] and with significant investment costs decrease, particularly in last several years [6].
References:
[4] Gilbert M. Masters, “Renewable and Efficient Electric Power Systems'', John Wiley & Sons, Inc., Hoboken, New Jersey, 2004, USA.
[5] REN21: Renewables 2013 Global Status Report, http://www.ren21.net, December 2013
[6] European Commission, DG Joint Research Centre, Institute for Energy and Transport, Renewable Energy Unit: PV Status Report 2013, Ispra, Italy, September 2013
