To have a better understanding of how solar electricity generation works, it’s important to understand the components of a solar energy system. A typical solar PV system consists of these main elements:
an array of interconnected solar PV panels
a battery storage system, if energy consumption is high
an immersion diverter to heat water
an electric vehicle (EV) charger
There are two types of solar PV panels: Monocrystalline and polycrystalline. The main difference is that monocrystalline converts solar energy to electricity using a single crystal of silicon, while polycrystalline uses multiple fragments of silicon. Monocrystalline is more efficient and sleeker, but comes at a higher price. Polycrystalline is less efficient, as there is less room for electrons to move in each cell, so as a result, they are cheaper than their monocrystalline counterpart.
The next component is the solar inverter. The inverter converts the solar energy (DC) captured by the panels into electricity that can be used by your home (AC). The inverter also performs various safety functions, constantly monitoring the grid and switching off in the event of a fault or major fluctuation in mains supply. Inverters come in two types: String inverters and micro-inverters, and we will also cover power optimizers.
String inverters are the most cost efficient, but because each solar panel is “stringed” together in a circuit-like system, there can be reduced overall performance if one of the panels drops in efficiency. String inverters are best for homeowners with a simple roof design that doesn’t suffer from any shading.
Rather than collecting all the energy and then inverting it, as string inverters do, micro-inverters convert DC energy into electricity at the site of each panel. As such, micro-inverters are more efficient than string inverters in the sense that a reduction in energy in one panel will not significantly reduce the energy conversion of the overall system. Micro-inverters are best for complex roof designs or roofs that are likely to suffer from shading, but there is an increase in cost, comparatively.
Power optimizers can be added to string inverter designs to increase the efficiency of panels that may suffer from shading. As such, power optimizers are the best choice for homeowners who do not want to commit to the higher costs of micro-inverters.
A battery storage system allows for unused energy that is generated during the day to be stored so that it can be used at night. Another cost convenience is that during the winter, you can fill the battery at night on a night tariff, and use less expensive electricity to power your home the following day.
Batteries can be bought in different powers and capacities and can be made of different materials: Lead acid, lithium ion, and saltwater. Lead acid has the shortest lifespan and lowest price; lithium ion has the second longest lifespan and second highest price; saltwater has the longest lifespan and the highest price. Likewise, the power rating determines how much electricity is generated, and capacity determines how long the battery is able to run. Increasing the power and capacity rating increases the overall cost.
Your solar panels work best in the summer months, which is precisely when to turn off oil or gas because you are no longer heating your home. The problem is, how do you heat your hot water? With an immersion diverter, you can divert excess electricity made during long summer days to hear your water. With an immersion diverter, you can turn fossil fuel heating completely off during summer months.
If you have or are planning to buy an electric vehicle, you can charge your EV with an installed EV charger. There is also an SEAI grant available for EV charger installation.
Going Solar is Simple
A solar system is a relatively simple system. The panels are attached to a mounting system which is attached to your attic rafters. The panels are either wired together with micro-inverters or a string inverter, turning the DC power created by the panels into AC electricity. The inverter is attached to the main power source in your home. If you have a battery, it is wired into the inverter. Excess power can also be diverted to your immersion to heat water.
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 of low electricity load, the PV will generate more power than is needed, and the excess is either used to heat hot water, stored in a battery for later use or spilled out to the grid.
Solar PV modules can be roof or ground mounted, ideally facing south, south east or southwest and at a pitch angle of typically 35-40 degrees. PV systems with arrays facing east and west also function effectively.
Once your solar system is installed, it is relatively maintenance free, except the panels do need to be checked once a year and commercially cleaned in order to operate at maximum efficiency.