Types of System
A Solar PV System comprises the following three key components:
- The Modules (panels)
- Monitoring Equipment
There are significant differences in efficiencies and outputs and costs. Below we give you an overview of each of the components.
There are literally hundreds of different Solar PV panels currently available on the market. PV modules (panels) come in a variety of shapes, sizes, colours, efficiencies and cost and choosing the right panel depends on:
- How much roof space you have?
- How much are you willing to spend?
- How much energy you need/want to produce?
Panel manufactures all have highly secretive and patented manufacturing processes which deliver significant differences in energy efficiencies per square meter. Two different panels mounted side by side will produce different outputs.
Panels come in different physical sizes and different wattage sizes i.e. you can have a 1.6m square panel which is rated 250 watts and you can have a 1.8m square panel rated at 230 watts.
Each manufacturer gives each panel a “w” (a watt) rating – i.e. the number of watts a panel will produce under peak “test” conditions. Typically panels range from 170w to 250w, with the “weakest and cheapest” panels being 170w and the most powerful being 250w.
Typically solar panels sit 50mm above the roof tile whereas there are some panels designed to replace roof tiles and are integrated into the roof – these are “solar tiles”. A system made up of solar tiles will typically cost twice as much as an equivalent panel system, although you will save money that you would have spent on roof tiles.
Once again there are many different types of inverter and they vary greatly in terms of performance and output.
A solar PV electrical inverter is designed to change the direct current (DC) electricity generated by solar panels into a usable form of alternating current (AC) electricity utilized throughout the utility grid and household appliances.
Solar panels are wired together in series (a “string” of panels) which increases the voltage and keeps the current low so that wiring is simpler and wire size can be smaller. String inverters are designed to be wired to a single series string of 8-15 solar modules and are currently the most widely used inverter type
Microinverters are typically attached directly to individual photovoltaic modules in order to extract the maximum power from each module. Microinverters are exceptionally reliable and typically come with 15 – 20 year warranty. They are highly efficient and can potentially produce more power than a string inverter; however they can add a substantial cost to a solar project.
Maximum Power Point Tracking (MPPT)
Maximum Power Point Tracking is an electronic system that manages photovoltaic (PV) modules in a manner that allows the modules to produce all the power they are potentially capable of. Because of this feature, the inverter acts as the “brains” of a solar electric system. PV cells have a single operating point where the values of the Current (I) and Voltage (V) of the cell result in a maximum power output. MPP trackers utilize control circuits or logic to search for this point to maximize electricity production.
It is vitally important to have decent monitoring equipment; whilst your inverter and generation meter will record and display the generation data these are quite often not easily accessible.
Being able to understand how much you are generating and how to optimise your usage is key to making the most out of your system.