Having considered system sizing and location already, the next thing to have an understanding of is what you will actually be buying when you have a commercial solar system installed. In this article, we’ll work through each of the major components and provide an overview of the major vendors and component features.
First up though a high-level consideration of component quality. To use an analogy if you’ve ever installed a new kitchen you’ll know there are a myriad of components you need to purchase. Refrigerator, ovens, dishwasher, stovetops, sinks, taps and so forth. For a few of these like the refridgerator, they might come from household brand names that you recognise like Samsung, LG, Fisher & Paykel, with this knowledge and some online reviews you can feel some confidence in forming a view on the quality of the different options. For the rest of the components though, things like taps, stovetops, they tend to come from brands you might never have heard of. As a result, purchasing decisions often rely heavily on price. More expensive options provide higher quality and more features, cheaper versions typically have lower quality and fewer features.
The situation is similar when purchasing a commercial solar system. You might have heard of a few brand names for one or two components if you’ve installed solar at home but for the most part they’ll be obscure. The challenge in comparing solar system component options though is that since the components are not sold to the general public, you won’t have visibility of pricing. Price as a comparison tool is lost. Furthermore, a given installer generally works with a small number of preferred makes and models so you don’t have the option of individually specifying components. The cost of the system is an amalgam of the component and installation costs.
Three factors to be conscious of in the panels you install are the type, size and quality.
Several solar panel technologies are readily available in the commercial market today. These include Monocrystalline (mono’s), Polycrystalline (poly’s), Monocrystalline PERC (mono Perc’s) and Bi-facial panels. On top of these different module types, there are frameless panels, DC optimised panels, AC panels and flexible panels – the list goes on.
Each technology has its pro’s and con’s, and you could be forgiven for being confused by competing claims of improved yield, low light performance, shade tolerance, etc.
Polycrystalline panels used to have a significant cost advantage over Monocrystalline panels and for this reason were more popular. However, the higher panel efficiency and power ratings offered by monocrystalline panels, coupled with a decline in module costs from greater scale, mean that monocrystalline modules tend to dominate commercial offerings that we see today.
Over time, the efficiency and peak capacity (kWp, used as a primary size reference) of panels continues to increase. The newest models have the highest capacity but often come at a slightly higher cost for a given amount of output ($/Watt).
If you are space constrained consider installing the highest capacity panels you can get, if not you might be able to optimise for cost. Bear in mind also that the same amount of labour is required to install a smaller panel vs a larger panel so larger panels can help reduce installation costs.
At the time of writing we’re seeing panel sizes from 275 – 350 Watts being installed.
As with any product, a spread of panels are available in the market at varying price points and quality. “Tier 1” is a common reference to panel quality which requires some caution as it’s not a formal or clearly defined term or specification.
A good basic filter to ensure you’re purchasing a minimum standard of panel is that it’s included on CEC approved list.
Some Solar PV panel brands that we commonly see:
Solar Panels produce DC power, which is similar to that stored in batteries and used by small appliances. The grid and electrical systems in your buildings all operate on AC power. The inverter converts the DC power produced by the panels into AC power so that it can be used on your site and fed back into the grid.
Inverters are about the size of the box that your electricity meter is installed in at your home and are predominantly made of circuit boards and electronics.
They should be installed in a shaded area to maximise performance. This can be on the rooftop itself or more commonly attached to a wall near other electrical infrastructure such as a distribution board.
As inverters are the interface to the power produced by your solar panels with the electricity network they’re subject to a number of Australian Standards as well as distribution network operator requirements. These standards are evolving and are updated from time to time. It’s important to ensure the inverters installed are compliant with these standards.
Features to consider in selecting an inverter
- Monitoring and reporting: Most inverters will include the ability to connect to their vendors Internet cloud to allow uploading of energy production, reporting and alerts. The user experience and quality of these monitoring interfaces vary between manufacturers. Noting also that it’s not uncommon for a standalone monitoring system to be installed as described below.
- Remote software update: Some inverters will use their Internet connection to enable the inverter software/firmware to be updated remotely.
- Noise: Whilst it’s not a desired feature, note that some inverters produce a level of noise from cooling fans that may be problematic if installed immediately adjacent to quiet areas such as offices or classrooms.
Panel level optimisation
If your rooftop is subject to some degree of shading, your system may include some form of panel level optimisation. This can be deployed either via:
- micro-inverters (e.g. Enphase units which are a small module mounted below the panels) in place of a string inverter (e.g. a larger box typically mounted to a wall or frame on the roof), or
- DC optimisers which can be provided by the main inverter manufacturer (e.g. SolarEdge) or as a third party device (e.g. Tigo).
Depending on the nature of the shading these devices might be found on every panel or shared between two panels. They can be installed on the entire system or just parts of the system impacted by shading.
For ease of installation, specialist racking kits are available which include a modular selection of fittings that enable installation of panels on all different rooftop types.
Good quality racking is important to ensure that it lasts at least as long as the solar panels and is not subject to corrosion or structural failure. The racking system needs to be user friendly to aid both efficient installation and access in future if individual panels must be removed for replacement.
Each installer will usually have a preferred racking system that they use across all of their projects and are familiar with.
Clenergy is frequently used and is also the only racking brand that we come across regularly.
Network Protection Equipment
For systems larger than 30kW, dedicated devices are required to ensure the quality of power generated by the PV system is acceptable, and that the PV system reacts in a supportive way to any unfavourable changes to the energy supplied by the grid. This includes frequency disturbances, voltage moving out of range or network supply outages.
The requirements for network protection equipment vary depending on the local solar configuration (for example single vs multiple rooftop systems) and between different network operators (state and region based).
When obtaining quotes for commercial solar systems above 30kW, you should check that the required network protection equipment has been included in the quote to avoid unexpected additional charges during deployment.
Some commonly used brands are:
Monitoring systems maintained high-resolution logging of energy production from solar PV systems allowing automated and remote detection of unexpected changes which may indicate system faults.
In the absence of monitoring, individual panel failure, inverter failure or systems inadvertently being disconnected can go unnoticed for extended periods of time. This comes with negative impacts on the return on investment.
Many of the major inverter manufacturers include monitoring systems either as part of the purchase price or as paid services. In addition, a number of third-party monitoring systems are available.
The existing electricity meter used for billing purposes will not have the ability to measure energy which is exported to the grid. In such cases, a new meter must be installed in order to track exports and obtain payment for energy fed into the grid.
We recommend ensuring a meter which incorporates automated uploading of usage data on a daily basis is installed. These should be available in most areas.
Approved metering models and brands are dictated by respective electricity distribution networks.
Electrical and other Balance of System works
Finally, in order to connect all of the components in your solar system, an array of electrical components and work will be required. These are usually not specified in detail on quotations but it’s worth having an appreciation of what they are.
In aggregate there can be a material cost associated with these components and the labour of installing them. The quality of equipment, care taken with and standard of installation can vary significantly between installers which will impact system pricing.
Poor quality components or workmanship in this area can readily result in system outages and failures of other system components.
- Cable conduits and trays
- Glands for installing cables through roof cladding
- DC isolation switches
- Circuit breakers
- Equipment labelling
- Shelters to shade inverters mounted on rooftops
Next step – learn about choosing a commercial solar installer.