There are two basic types of solar energy.
1. Solar thermal where heat from the sun is used to produce hot water or steam.
2. Solar Photovoltaic (PV) which converts light energy into electricity.
Solar PV is the fastest growing renewable energy source in the world and is forecast to be the dominant source of renewable energy in the world by 2050. Here in Ireland, this may not necessarily be the case as our climate favors wind energy. Nevertheless, solar energy will make up a sizeable share. There are several reasons for this.
Technology and cost: The efficiency at which solar PV technology converts light energy to electricity is constantly increasing. Widely available solar panels (referred to as modules) had a typical conversion efficiency of 13 – 14% in 2010. Now 1n 2021, due to continuous technology improvements typical conversion efficiencies are 19 – 20% and expected to reach 24 – 25% by the mid to late 2020s. In addition to this, the cost of solar PV technology has plummeted by a factor of 8 over the past 10 years due to a dramatic increase in manufacturing volumes – productivity, more competition, especially in Asia, and more robust supply chains.
Climate: It is often purported that Ireland does not have a suitable climate for solar. Although it is behind solar irradiation levels in for instance the Mediterranean – Middle East and North African countries, it is still acceptable. Sunstream Energy’s own south-facing roof system installed in December 2009 has averaged 1,070 KWh / KW over the past 11 years. This is equivalent to solar yield levels in Southern UK, Northern France, Netherlands, Belgium, Northern Germany, countries which have an abundance of Solar PV installed.
System overview: Modules are connected in series to form a string and one or more strings are connected in parallel to form a solar array. Once a PV system has been installed, it can provide energy at essentially no cost for years as it is virtually maintenance-free. A typical solar PV system consists of three or four main elements:
- an array of interconnected solar PV modules producing DC electricity.
- an inverter(s)
- cables and switchgear
- Battery energy storage (optional)
The inverter is an electronic device that converts the DC electricity produced by the solar array into AC with the same voltage and frequency as the mains supply. The inverter also performs various safety functions, constantly monitoring the grid and switching off in the event of a fault or major fluctuation in the mains supply. The inverter feeds electricity directly into the property’s electricity distribution board in addition to the mains supply from the grid. Solar electricity gets priority over grid power so the appliances in the building will use the free electricity generated from the solar PV system and any surplus power will be automatically exported to the grid.
On a sunny day, the power generated by the solar PV system reduces the amount of electricity that needs to be bought from the electricity supply company. On very sunny days, or at times when the electric load is low, the PV may generate more power than is needed, and the surplus will be exported to the grid and or diverted to battery storage/water heating or other heating cooling appliances for reuse later. An export feed-in tariff will is set to be introduced in Ireland in July 2021
Solar PV modules can be roof or ground mounted, ideally facing south and at a pitch angle of typically 35 degrees. PV systems with two or more solar arrays, facing east and west also function effectively. Sunstream Energies Solar Energy Fence™ is a more focused East-West arrangement targeting maximum solar generation early in the morning and later in the evening. A selection of Sunstream Energy’s PV installations over the past 15 years can be seen in the ”Projects” section.