Any solar system will have three core components. These components set the goal posts for energy generation, profitability and the overall appearance of the PV:
- Solar panels
- Mounting system
While there are other add-on components – such as immersion diverters, batteries, and so on – the choices you make on panels, inverters, and mounting systems will form the core backbone of any system. So, in this article we’ll briefly discuss the options out there.
These form the core generating asset. While they come in various shapes and sizes, the standard technologies (polycrystalline and monocrystalline) typically have dimensions around 1.5m by 1m, and weigh around 15kg each.
Key choices to make in choosing a solar panel always depend on the specifics of your project. If you’re thinking about a large, ground mount solar plant – perhaps for a commercial property – then it may be worth going with a cheaper solar panel. But if you’re looking at a long-term minimal maintenance roof mount, higher quality PV may pay off in the long run.
As well as traditional panels, there are other innovative technologies which are good in specific applications. For example, thin-film is perfect for building façades, while bifacial PV is great for generating more energy. There are also roof and building integrated options from British manufacturers like Viridian, or GB Sol with ‘solar slate’ tiles.
It’s important to note is that in most cases, all your solar panels need to be the same make and model. This is for two important reasons:
- A series of PV modules will (without power optimisers) only output as much energy as the worst performing module on the string.
- Dimensions of replacement panels need to be an exact match so that the panels can be mounted together.
Your site and needs determine the best mounting system for you.
- Roof mounts are screwed directly onto building rafters, and take up the space of a few tiles.
- Ground mounts are sunk into the ground, on concrete piles or just buried in.
There are a few different choices to makes here. So solar panels can be changed easily, large solar farm installations often choose modular rack-mounts. In contrast, homeowners will often place panels on their roof, while those looking for a sleek look often choose smaller, more flush mounts such as some from Renusol. As well as this, there is a range of domestic groundmounts and solar carport systems from suppliers such as Solarport Systems providing a range of choices to commercial or domestic solar investors.
The key decider here is simply where you want your panels, and how you want them to look.
Inverters process your solar energy, converting it from DC from the solar panels to the AC current used in homes. This process involves some losses in power – which can be mitigated by correct sizing of the inverter, and good overall system design.
Standard inverters will be rated to a certain power – i.e. 2kW, 3kW and so on. This refers to the maximum power output of the inverter. The number and type of panels you have will determine the chosen inverter size. For example, if your system has twelve 330W panels, you know that the maximum DC energy that will come from the panels will be in the region of 12×330=3960, or 3.96kW. This means that a suitable inverter should be somewhere in the region of 4kW.
There are two decisions to make here:
- A standard inverter or micro-inverter system setup
- The manufacturer of the inverter.
It is also worth bearing in mind that the inverter is also what will provide you with monitoring of your PV’s performance.
Microinverter vs. Inverter
Traditional inverters process all your solar energy in one place, by connecting to strings of solar panels located elsewhere – for example, a standard roof mounted PV array will often feed back to a central inverter in a loft or garage.
Microinverters, in contrast, are located in the same place as the array, and are installed strung between panels. There will be multiple microinverters for the same system, each processing a smaller amount of energy individually.
The two set-ups have benefits and drawbacks.
- Microinverters perform much better where parts of the arrays are shaded during the day – so for rooves with prominent chimneys, or arrays near large trees. Net power output can increase by as much as 30% for these systems.
- Microinverters can also take up less room, which is a benefit where space is at a premium.
- The central location of a standard inverter allows for simpler maintenance, often resulting in cheaper repairs should something go wrong.
- Microinverters on rooftop PV system can sometimes require scaffolding to repair, which can negate the cash benefit of additional power output.
- For the same system size, a single inverter will often be cheaper than multiple microinverters, and cost less to install.
The key reason the inverter manufacturer matters is similar to why it matters for solar panels: Quality, and Warranty.
For microinverters, there is only really one current choice: SolarEdge were the first to establish themselves in the field, and their inverter warranties of 12 years as a standard up to 25 years makes them attractive compared to standard inverters.