Installing a solar power system is a proven way to reduce your electricity bills, which is a very attractive proposition with the high kilowatt-hour prices in Australia. Although solar power systems are simpler to install and service that other types of energy generation equipment, their complexity should not be underestimated either. Like with any engineering project, adequate planning and design are vital.
The benefits from a solar power system are minimised if it is poorly designed or installed. You must also ensure the proposed solar array is a good match for the building where it will operate. For example, consider the installed capacity: a solar array of residential scale will not have a significant impact on a large commercial facility, and an oversized installation forces you to export too much electricity to the network at a low feed-in tariff.
This article describes some common mistakes when going solar, their consequences, and some recommendations to prevent them.
Hydroelectric turbines stop producing electricity if you close the water supply, and steam turbines in conventional power stations require fossil fuel combustion to vaporise water. The same logic applies for solar power – place a photovoltaic module under a shadow, and you will notice its output drops dramatically.
Even small shadows can reduce the productivity of your solar array, due to how photovoltaic panels are wired. The solar cells in a module are wired in series, and the modules in a string circuit are also in series. If even a single solar cell is covered by a concentrated shadow, the series current drops and the entire string circuit is affected.
Shadows can be deceiving: since the sun’s position in the sky changes throughout the day, an unshaded area in the morning can be covered in the afternoon. In other words, solar designers must analyse how shadows move, not only their location at a given time of the day. Thankfully, solar design software can simulate shadows based on geographic location and the height of obstacles around the project site.
Some shadows can simply be avoided when specifying the layout of the solar array, or it may be possible to relocate the object casting it. However, there are also cases where shadows are unavoidable – solar power has limited usefulness if a property is constantly shaded by taller buildings.
Solar power is clean and sustainable, but don’t forget you are dealing with an electricity generation system. Most installations use a grid-tied connection, which means their power output is synchronised with the electric service. Considering that your installation interacts with a power system used by many other consumers, there are minimum technical requirements.
Before deploying a solar array, you must also make sure your property is not a historic landmark or part of a historic district. Solar panels are an excellent property upgrade, but they also give a modern appearance to buildings, which local councils may prefer to avoid. In some cases, solar panels are only allowed if they face away from the street, or they are not allowed at all.
You can maximise generation by covering a rooftop completely with solar panels, but this approach is not always cost-effective:
Consider a solar energy output of 1,000 kWh per month, in a property where the client pays 35 cents/kWh but only gets 11 cents/kWh for exports. You save $350 per month by consuming these 1,000 kWh, but only get $110 if you export them.
Making your solar array twice as large will not necessarily double your savings. Solar generation is less valuable when you export it instead of consuming it, as explained above, and oversized arrays have a plenty of surplus production. Ideally, your solar system provider should optimise capacity according to your needs.
The approach is different if you are considering batteries for the solar array. Since batteries can hold electricity for later, you can use a larger array and still consume its full output.
Solar power systems add a load of up to 20 kilograms per square metre to your roof, and you can have major issues if the structure does not tolerate this load. A reliable solar provider will perform a structural assessment before proposing a photovoltaic array.
Roofs with fiber-cement shingles are brittle, and solar panels can only be deployed with a special type of racking that doesn’t cause cracks. In older roofs you may also find asbestos-containing materials, which can only be handled safely by companies specialised in asbestos abatement.
Solar PPAs and leases are attractive because you can get solar power without an upfront investment. However, it is very important to read the contract closely to make sure you are getting a good deal. This should not be an issue if your solar provider has a solid reputation, but make sure the contract does not have clauses that work against you.
For example, a key benefit of a solar PPA is delegating system maintenance and component replacements to the provider. If a contract tries imposes this responsibility on you, look for other options where the provider includes the service. Also make sure the kilowatt-hour price is stated clearly, since contracts may have ambiguous clauses that impose additional fees.
Having a good design from the technical standpoint is very important to get maximum benefits from solar power, but you should not overlook interconnection requirements, permitting and other legal aspects. A reliable solar provider will work to deliver the best solution for your property, without imposing complex requirements and conditions.