AS ONE SCRIBE PUT IT, BUYING THE BEST QUALITY SOLAR PANELS AMOUNTS TO SQUAT IF YOU PAIR THEM WITH A CHEAP AND NASTY INVERTER. UNFORTUNATELY THERE IS NO TIER SYSTEM EQUIVALENT FOR INVERTERS.
Customers need to rely on more traditional methods of choosing products. A couple of years ago Choice Magazine did a fairly extensive study of members’ satisfaction with solar power systems.
Notably, 33% of members reported having problems with their systems, and 2/3 of these were related to inverters! It’s definitely worth investing a bit extra in inverters.
Also, while feedback on the different types of solar panels was pretty even, feedback on inverters did vary a bit.
The Choice article noted that, similar to the case for solar panels, there are a lot of inverters on the market with no-one being really dominant. That said, the most popular brands in Australia are Enphase (microinverters), Fronius and SMA.
Note Sunny Boy is actually an SMA product. The study suggested that the people who responded as having Sunny Boy systems tended to have older systems which may explain the different ratings.
Similar to solar panels, probably even more so, inverters are sophisticated devices with a high degree of complexity: we’ve already seen they are the most problematic part of the home solar system.
The inverters’ main role is to convert the DC power from the solar panels into AC power for the user and/or the grid.
Given the problems with inverters, it’s probably best to stick with the brands that have been around for a while, have a good reputation for quality, and demonstrate innovative new technologies.
In addition, making sure the company has a good support base in Australia, in case things go wrong, is very important.
One company that is introducing a new generation of innovative inverters that aims to deal with inverter problems is AISWEI with its new “Solplanet” range. The AISWEI Australia branch was launched at the All Energy Conference in Melbourne late last year, however AISWEI has a robust history - it was formerly the Chinese subsidiary of SMA and Jiangsu Zeversolar New Energy Co. Ltd.
The Solplanet range of inverters has been created to address the quality and reliability issues that plague the industry. In addition, key innovations have been introduced that reduce cost and make life easier for installers. The range currently consists of inverters ranging from 1kW to 50kW.
They can be single phase, three phase or hybrid. The company has put a lot of focus and e ort into quality and reliability, through manufacture, testing and accreditation. To ensure quality they have taken control of the whole manufacturing process from raw materials to final product.
AISWEI also has fully accredited laboratory and testing facilities, enabling innovative R&D (particularly with the core of the inverter, the electronic board), and extensive testing of components and products.
The innovation doesn’t stop with quality control. Solplanet’s housings are die-cast single pieces that maximise sealing of the internal electronics. Through an innovative communications platform, installers are able to alter inverter settings using an app, therefore opening the housing is unnecessary, further avoiding problems during installation.
This communication ability makes life easy for installers that have to cope with different standards in different parts of Australia that require different inverter settings. The app also enables simple monitoring for both installer and customer. The other feature that puts Solplanet inverters at the top level is a built-in DC isolator. This negates the need for more expensive external isolators.
Solplanet inverters are rolling out across the globe. With inverters being both the critical part (the brains) of solar energy systems and also the most problematic part, AISWEI certainly seems to be on the right track.
So that’s our recommendation but before you shoot off, a bit of background on what inverters actually do.
Your inverter manages the flow of power throughout your system. When panels collect energy from the sun, they generate DC (Direct Current). But most home appliances use AC (Alternating Current). At its core, the inverter has a simple job: it converts captured DC power into usable AC power. When you wire your system, the inverter lives between your solar panels and the appliances you intend to power. But the wiring diagram changes slightly depending on whether you are feeding power into the grid (the default choice if you have access to power lines) or into batteries (if you live off the grid).
A grid-tied inverter takes DC power from solar panels, turns it into AC power, and uses that to power your appliances. Any excess energy gets sent into the grid for credit. This system works a lot like a bank account. The utility company keeps track of how much energy you feed into the grid, which is credited to your account balance. When you withdraw power, the energy you use is deducted from your balance. Grid-tied inverters are simpler and easier to wire since there are usually only two main components. The panels feed direct current (DC) into your inverter, which converts to alternating current (AC) to power your appliances. Any extra power flows out of the house into the grid for credit.
But an off-grid inverter needs a battery bank to function, so the power chain changes a bit. In off-grid systems, panels generate direct current (DC), which is fed through a charge controller into a battery bank and stored as DC energy. When you draw power, it’s sent through the inverter to be converted to alternating current (AC), then used to power appliances on demand.
If you expect shade or other obstructions to cover the area where you plan to build your system, we recommend string inverters. For string inverters, string sizing must be taken into account. A string is a group of panels wired in series into the PV input on the inverter. For example, you might have eight panels strung into a single input. So why does string size matter?
Inverters operate within a specific input voltage range, called the operating range. Your panel strings must output a voltage that falls within that range. If the panels don’t supply enough voltage, the inverter won’t have enough power to turn on. If too much voltage is supplied, you can damage your inverter and void the warranty. Ideally, your panel strings should be sized to hit a sweet spot to keep your inverter running at its optimal efficiency — referred to as the maximum power point (MPP) range. String sizing calculations depend on the specific voltage of your panels and inverter, as well as outside factors like temperature.
Putting a solar system on your roof certainly requires a maze of decisions around the many different types and brands of both solar panels and inverters. Thankfully there is a lot of information available to help, and strong, stable companies with a long history of supply.
As long as you’re not paying peanuts for products, and do a bit of research, you’ll almost certainly be fine. Just make sure the installer is reputable!