A solar panel optimiser uses maximum power point tracking to improve the output of each solar panel in a PV array. This helps improve the performance of a PV system when conditions like shading can cause some panels to underperform while allowing the rest of the string to operate normally.
If you’re thinking of going solar or already have a solar power system installed, you’ll want to know how to get the most out of your system.
As solar technology improves, solar optimisers have emerged as devices that help owners get the best value from their PV systems. They are popular for helping to overcome certain situations that reduce the overall output of PV systems.
But what exactly are solar optimisers, and how do they work? And as a consumer, what solar optimiser should you choose?
This article will provide the answers to these questions and more.
Let’s begin by outlining solar optimisation.
What is Solar Panel Optimisation?
Solar panel optimisation is also known as Panel Level Optimisation (PLO). It includes devices called MLPEs (Module Level Power Electronics) for solar panel installation to optimise the power output from each solar panel individually.
Solar panel optimisation is about obtaining the maximum amount of usable electricity from each solar panel in a PV system. It does this by adding an extra feature to the modules.
External conditions like shading can cause reduced performance in solar panels. And if one particular panel in a string has a “problem” and performs poorly in a conventional solar installation, it will force the rest of the panels to perform at the affected level.
For example, if a panel is shaded and only generates 50% output, the other panels in the string, though unshaded, will mirror the output of the affected panel – averaging a 50% output.
Reduced system output from a conventional system
Solar optimisation is about ensuring that the performance of solar panels in a string is unaffected by a single panel that is performing sub-optimally. Each panel in the string generates maximum output irrespective of the performance of other panels.
Output from an optimised system
What are Solar Optimisers?
Solar optimisers are devices used to maximise the energy output of a PV system. They are the Module Level Power Electronics (MLPE) that are added to solar panel installation so that each solar panel produces their maximum energy output.
They can be added to one or all panels in the string, and when you have them, you can be confident that a shaded panel won’t bog down the energy output of the entire array.
What about Bypass Diodes?
Bypass diodes may improve the solar system performance under shading conditions, but they don’t optimise solar panels individually.
The wiring of a solar panel lies in three columns called cell strings, with each cell string containing a bypass diode. The effect of shading on a given cell in the panel is similar to a clog in a water pipe – at the shaded end, internal resistance increases, which restricts the current flow.
The bypass diodes are activated when this hindrance occurs and reroute the current via a “shortcut” to the following cell string; when this happens, the panel voltage is reduced by a third.
Bypass diodes also deactivate when there’s significant shading because the voltage is too low, which can cause the entire system to shut off.
Solar power optimisers were developed as superior solar technology to overcome shading issues; they perform panel-level optimisation so that the performance of other panels in a solar system isn’t compromised by one underperforming component.
How do Solar Panel Optimisers Work?
Solar optimisers work via a solar technology called Maximum Power Point Tracking (MPPT). Using this technology, the optimisers track the maximum power of each solar panel in real-time and regulate the voltage before transmitting it to the solar inverter. So, no matter how the other panels perform, your solar panel system will reach maximum power production.
Different Types of Solar Optimisers
There are four types of solar optimisers:
- Discrete DC Optimisers
- Smart Panels
- Maxim Panel
- Microinverters
1. Discrete DC Optimisers
These optimisers are the second most expensive solar optimisation option.
It takes a tiny device (called a DC optimiser) and attaches it to the solar panel (one DC optimiser per panel).
The solar panels are then joined in succession during installation, and the string connects to a single solar inverter (DC to AC inverter).
The power generated by the PV array is transmitted at a high voltage across your roof.
Discrete DC optimisers attached to solar panels in a series string
Unlike integrated DC optimisers, discrete optimisers are separate devices added to individual solar panels to improve their respective performance.
You don’t need a DC optimiser on every solar panel; you can simply identify solar panels prone to shading and add the device to those panels, saving you money on your solar panel optimisation.
One of the best producers of DC optimisers is Tigo. The company started in the solar industry in 2007, making solar panels with DC optimisers on their backs, but it has since shifted its focus to just designing individual optimisers.
2. Smart Panels
A smart panel is just another name for an integrated DC optimiser. It’s a solar panel with a DC optimiser usually pre-installed at the back of the panels as one entire factory unit.
Since each panel has its own built-in optimiser, you can’t choose to have the DC optimisers in only certain collectors. However, buying one of these is cheaper than buying a standard solar panel and a DC optimiser separately.
A standard PV connection applies when using smart panels. You connect the panels in sequence and then connect the string to any solar inverter.
Many of the smart panels in the market come from a collaboration between DC optimiser company Tigo and modules manufacturing companies such as Jinko Solar, Canadian Solar, and Trina Solar, to name a few.
3. Maxim Panels
Maxim panels are the cheapest solar panel optimisation option. They are produced by a microchip company called Maxim Integrated.
In the maxim panel optimisation, one panel has three tiny optimisers attached (one to each cell string), linking three bypass diodes to reduce the effect of shading. However, these chips don’t bypass the pathway from a shaded cell and send current through another path; instead, they boost the current of the weaker cell to match those of the stronger cells.
So, while discrete DC optimisers and smart panels are solar panel optimisers, the maxim solar optimisers can be considered ‘‘solar cell optimisers’.
Solar panel optimisers vs maxim solar cell optimisers
Maxim Integrated does not exactly manufacture solar panels. They produce the ‘Maxim chips’ (cell optimisers) and sell these to panel manufacturers to make the ‘Maxim panels’. These manufacturers include Jinko Solar, Suntech, Trina Solar, and ET Solar.
The Maxim solar panels are also connected in a sequence, with the series string attached to a central inverter that works well with all string inverters. However, Maxim panels lag behind their competitors in the current Australian market.
4. Microinverters
Microinverters are the most expensive solar panel optimisation option. As the name suggests, a microinverter is a miniaturised inverter.
Microinverters take a different approach to solar panel optimisation. The panels are neither connected in a series, in a string, nor to one central inverter. Instead, the panels are joined in parallel, and a tiny microinverter is fitted on them.
Each solar panel has its own inverter and integrated optimiser in this optimisation option, allowing each collector to function independently, preventing one collector from being brought down by another underperforming one.
Solar Optimisation Using Microinverters Boasts Several Advantages.
- Low Voltage On Your Roof
In a conventional installation, a DC voltage of up to 600V will travel across your roof to the string inverter. This high voltage poses serious arcing and fire risks.
With microinverters, the DC to AC power conversion occurs at the solar panel level, and the power is transmitted at a comparatively low voltage (240 V AC).
- No Central Point of Failure
If the central inverter fails in a typical installation, the entire system is grounded, and energy production halts. But with a microinverter optimised solar system, if a microinverter fails, you’ll only lose power generated from the solar panel directly connected to it.
Which Type of Optimiser Should You Choose?
The best optimiser for your needs will depend on your budget and safety concerns.
When to Choose Maxim Solar Panels:
You want the most budget-friendly optimisers. Unfortunately, Maxim solar panels are no longer viable for most consumers. The panels are quietly exiting the Australian market.
When to Choose Smart Panels:
You want the most budget-friendly optimisers in Australia. With maxim panels no longer available in Australia, the smart panel is the next best choice for the budget-conscious Aussie.
When to Choose Discrete DC Optimisers:
You are budget conscious and face only minimal shading. Discrete DC optimisers have the benefit of being separate from the solar panel. As a result, you can attach them to some panels and leave them off others.
This works nicely if you’ve only got a few shaded panels every now and then. Instead of having optimisers on all panels (including those operating optimally), you can simply attach the optimisers to panels whose outputs are likely to be affected by the shading.
Having fewer optimisers relative to solar panels means you’ll also save more with discrete DC optimisers than with integrated DC optimisers.
When to Choose Microinverters:
Rooftop safety is a significant concern. Properly installed solar energy systems carry a very low risk of danger. All optimisers also have built-in safety mechanisms that shut down the solar panels if a fault is detected.
However, microinverters are safer by design. With the other optimiser options, the power generated is transmitted in high voltage DC that can reach up to 600 V. In the case of DC arcing, having such high voltage shooting across the roof can be frightening.
But in microinverter installations, the power generated is quickly converted to AC power and then transmitted across the rooftop at a relatively low voltage (240 V).
Knowing the similarities and differences between DC optimisers and microinverters will also help you choose the correct solar panel optimiser.
For example:
DC optimisers are easier to integrate with solar batteries, so you may decide on the discrete DC optimisers or smart panels if your solar system includes battery storage.
Microinverter systems are easily scalable because each solar panel works independently. You can quickly expand your existing system by adding a new “micro-inverter + solar module combo.” The solar modules are sized according to the DC power input of the string inverter. You may have to adjust the string inverter if you need to increase the size of your system.
So, if you want to start small and later increase the size of your solar system, you may find microinverters the sensible option.
Who Can Install a Solar Panel Optimiser?
Solar panel optimisers should be installed by CEC qualified installers. If you are just going solar, it might be best to add optimisers to your system so that the solar installers can manage the installation along with your solar power system.
If you already own a solar power system, you can call on a solar electrician to install the optimisers for you.
Don’t try installing them yourself, even if you know what you are doing. The only exception should be if you are already an accredited solar installer/electrician.
Are Solar Panel Optimisers Easy to Install?
Solar panel optimisers are generally straightforward to install. However, this does not make their installation a mere DIY project.
To install the SolarEdge power optimisers, the first thing to do is equipment grounding. Installers insert a single star washer between the metal plate on the power optimiser and the rack.
The next thing is wiring the optimisers together, made easy by their male-female locking connectors.
Lastly, the power optimisers are connected to the PV modules. It’s as easy as clicking together the two short cables from the optimisers and those on the PV modules.
Are Solar Panel Optimisers Worth It?
A solar panel optimiser is an additional feature that adds to the cost of your solar installation. However, solar optimisers are ultimately worth it because they help you fight power losses, leading to a quicker return on investment.
True, the cost of an optimised solar power system is more than that of a comparable standard system. The difference depends on the type of optimiser you use.
For example, consider the standard 6kW system, the most popular solar system installed in Australia in recent years.
As of writing (early 2022), this 6kW system will cost you approximately $5,000 – $9,000. But optimising it will add the following to your installation cost:
- $2,000 (for microinverters)
- $1,600 (for discrete DC optimisers)
- $1,200 (for smart panels)
- $500 (for Maxim panels)
However, the advantages of solar panel optimisers far outweigh the cost of adding them, especially if your system suffers from shading or other conditions that result in power losses.
The optimisers ensure that your solar panels always deliver the maximum power output.
With more solar energy harvested, you have two main options:
- Increase your self-consumption. This reduces the electricity you’ll need from the grid and positively affects your electricity bills.
- Export more electricity to the grid. This allows you to earn more money from your excess electricity.
In either scenario, you benefit from energy savings. As a result, you’ll be able to recover your solar installation cost more efficiently.
Who Should Have a Solar Optimiser?
A solar optimiser is helpful for any of the following:
- Complicated rooftops
- Excessive shade
- Optimising your system
- Panel-level monitoring
1. Complicated Rooftops
If you have a simple rooftop (one which faces only 1 or 2 directions), you may not require solar optimisers. The only exception, in this case, is if your simple rooftop is typically shaded.
However, if your rooftop is complicated (facing more than three directions), you definitely require solar optimisers.
This is because one of the elements that affect the production of solar systems is the direction that the panels face.
For example, with Australia located in the southern hemisphere, the sun’s direction moves towards the north. Thus, north-facing solar panels deliver the best output. East and west-facing panels will reduce output by 10 – 20%, while north-facing panels can reduce output by roughly 28%.
That said, if your complicated roof causes your solar panels to face different directions, you will certainly benefit from optimisers, as they can maximise the output of your panels.
2. Excessive Shade
If one panel in a solar system is shaded, energy production is significantly affected. So, if you constantly experience even partial shading, you should seriously consider solar optimisers.
These optimisers will ensure that unshaded panels operate optimally while also providing the best possible power output from the shaded panel.
3. Optimising and Maintaining Your System
Even if you have a simple rooftop and don’t suffer from shading, you may still consider installing optimisers if you desire optimal production from your system. This is because several factors can affect a panel’s efficiency.
For example, a cloud moving in the sky can cast a shadow on your solar panels to temporarily cause a drop in energy production.
Dirt on a solar panel can also reduce its efficiency, lowering the amount of power produced. If the electrical parameters of some solar cells or modules differ from those of other cells or modules, the mismatch effect can cause power losses. This can also be resolved via cleaning your solar panels.
With optimisers, your solar power system will capably address these situations (solar module mismatch, soiling, and cloud cover). It’ll provide you with about 8 – 12% more energy from your system.
4. Panel-level Monitoring
The solar panels that form a string operate as “one” unit in a conventional solar panel installation. So, you can monitor the production of the line instead of the performance of individual panels in the series.
But in optimised systems, the optimiser attached to each solar panel makes it possible to view the output of each unit, giving you individual panel monitoring.
Do Power Optimisers Work Under Extreme Environmental Conditions?
Power optimisers are quite robust, just like the solar panels they complement. So, they can operate under extreme environmental conditions.
However, when performing under harsh conditions, they are less efficient.
With the maximum power point tracking function of optimisers, not only do they function under severe weather conditions, they drive your solar panels to perform better under such situations.
Are Power Optimisers Safe to Use and Install?
Generally speaking, power optimisers are safe components in solar systems because they come with an automatic DC voltage shutdown system.
The optimisers ensure that the solar power system automatically de-energizes if power from the grid is interrupted in any way.
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