We’re going to focus on the peripheral technologies that have developed in the last 10 years to support PV installations. We will look at multiple developments in areas like electrical connectors, mounting and tracking systems, and PV cleaning systems …
We know that solar installations have grown at an exponential rate during the last 15 years. As they grew, so did the technology that ensured easier installations and efficient monitoring and operation of PV panels.
For example, we now have better standardized connectors, better mounting frames, cheaper and more robust tracking systems, and multiple solutions for keeping the panels clean. Let’s review all of them one by one.
First up, we look at the connector technology. Now if you remember the early solar panels, they came out with all kinds of connectors and sometimes all you got was panels with bare terminals that were permanently connected to the junction box using a strain relief.
What are mc4 connectors?
Even today a lot of low cost panels come with bare terminals, which isn’t a good idea given that the panel voltages are getting higher. Coming back to the connectors, there were no standard connectors for solar panels before 2011. The panels came with everything from banana connectors to more bespoke connectors, like redox and MC3 connectors.
The need was felt for more standardized connectors across the board that would provide waterproofing and arcing protection. There was also the need for a push fit type terminal that would be easy to connect for roof installations, but would not be easy to disconnect. That is, it should require a tool to uncouple to avoid accidental disconnect if the cables are pulled.
Thus, the MC4 connector was born. The wires can be connected to it mainly by crimping and also by soldering. The MC4 connector eliminated the problem caused by water leakage, electrical corrosion, and mechanical stress on the wires. Today one can also buy high quality junction boxes separately to the solar panels.
As the panel voltage is increasing the solar panels are becoming susceptible to PID or potential induced degradation. This results in loss of output as charge leaks to the panel’s aluminium frame. To avoid such a scenario an anti-PID device is now available that manipulates the voltage and current output of the panel to minimize these losses.
Solar panel monitoring system
Another development during the last 10 years is the monitoring technology of the output from the solar panels, which now you can add if you don’t already have it. As you might be aware that many high-end solar inverters come with a fantastic software with which you can monitor the production of your solar array.
They also store data on the clock to allow you to compare the power output to any time period in the past. Therefore it allows you to generate reports for weekly, monthly and early production of how many units of electricity you produced. For people who have an old inverter, or an inverter which does not have the monitoring and logging feature, there is good news.
There are many suppliers that are providing devices that will connect to your solar installation and with these devices in place one can monitor the output of the panels on their phone anytime and anywhere in the world.
Let’s focus our attention now on the installation and tracking technology. Ten years ago there were limited options with regards to roof racks and rails to install the solar panels. Today there are a variety of options for all kind of roof structures that make the installation quick and easy.
There has been standardization of solar panel thickness and most of the panels are now between 30 to 48 millimeters thick. This has led to the development of roof attachments, mounting fasteners and racking systems that can cater to all types of panels in the market.
Solar panel mounting brackets
More interestingly, there has been a system developed that requires none or minimal invasion on roof structures. Solar panels can be mounted without drilling any holes in the roof, although it has to be mentioned that this system requires local wind conditions to be below a certain threshold.
The other development on the non-obtrusive solar installation concept is the roof integral PV which replaces the tiles all together. Instead of the panels being mounted on the top of the tiles, the panels replace them to become the roof. Specialist installers are required for such installations and also a particular solar roofing membrane is required.
These have not been as successful till now as was anticipated primarily because of the cost. On the other hand, for the tracking system the cost has come down considerably. Most tracking systems are deployed on ground mounted PV panels as the panels have become larger and more efficient.
Video and transcript by kind permission of Synergy Files
Single-axis solar tracker efficiency
The tracking system that serves them has also become more feasible. With the 10% extra cost, one can gain 30% more output. If a single access tracking is the only option, then polar tracking that allows the panel to face and move from East to West is the most effective.
During the last 10 years some progress has been made to add some degree of tracking to roof mounted systems. There are low price mounts available that allow tilt adjustment to cater for seasonal variation. Around 10% higher gain can be expected just by increasing the tilt angle by 5 to 15 degrees during winter, depending upon your latitude.
Lightweight polar axis tracking for flat roof installation is also available but it does require spacing between the panels for the panel arrays to operate efficiently. As the price of the panel has come down significantly, the current trend is to use more panels at fixed angle rather than less panels on tracking system to get the desired level of output power.
Having covered the progress and development in electrical and installation technology now let’s now look at cleaning of solar PV panels. It is common to find layer of dust or bird soiling accumulating on the solar panel after installation. This is particularly true for regions with low precipitation.
Do you need to clean solar panels?
Frequent rainfall can cleanse the panel but in areas where there is little rainfall, dust and bird soiling can lead up to 30% drop in power. Given that just like most things we would like to see PV panels as maintenance free, some solutions have emerged that address the problem.
For larger arrays there are robotic cleaners that are made on the similar technology as automated lawnmower and vacuum cleaners. They do require specific rails to traverse across the panels. If the cleaning is to be wet, then plumbing lines also need to be attached.
Once installed they can take away the burden of cleaning the panels that can be very inaccessible. This is, however, a costly option. A much lower cost option is to apply nano coatings to the panels.
Hydrophobic solar panel coating
There’s a specific self-cleaning hydrophobic solution that doesn’t allow bird faeces and water droplets to settle on the panels.
A 250 millilitre bottle of this coating liquid is sold for $50 and is enough to cover a three kilowatt array. The coating also doesn’t allow the rainwater to form a reflective layer over the panels, which can reduce the transmittance of light. When applied, the water instead forms droplets and rolls off.
It is said that the coating lasts for up to 5 years. It pays itself back well under a year, both by saving your cleaning bills and through the higher power output of up to 27 percent. In wet weather anti-bird nettings and meshes can be installed to prevent bird nesting in the gap between the panels and the roof. This also eliminates soiling to an extent.
Several window cleaning services now provide solar panel cleaning service too. The recommendation is that the panels should be cleaned at least twice a year. Two other developments in peripheral technology are the immersion diverters and polymer stickers to increase the panel output.
Immersion diverters are very suitable for people who don’t have a battery bank but would like to utilize the energy produced by their panels to the fullest. It works on a very simple principle. If the device notices that panels are producing a lot more than what is being consumed in the house, then rather than exporting the power to the grid, it simply diverts that power to an immersion heater in the hot water tank to heat up water.
It has to be understood that water can store a lot of energy. That hot water can then be utilized for space heating or cleaning. Although simple in concept, the immersion diverters can save you a lot of money. Given that in many parts of Europe and North America over 57% of the energy used goes to space heating, this device can pay itself back within two years.
The other item worth mentioning is the fusion polymer sticker that was developed by a startup company called Genie Lens in 2010. This sticker could be applied to any solar panel. The polymer film was embossed with a microstructure that bends incoming light and allowed the material on the solar panel to absorb more light and convert more of it into electricity.
Tests prove that the film can increase the power output on an average between 4 to 12.5%. Although this product is no longer available in the market, the idea sparked research on nano-structured film for solar panels. Whenever these films hit the market, there would be a huge boost to the solar industry, as they could be applied to new as well as older installed panels.
Solar Installation Parts and Components – Related Questions
What is solar panel monitoring?
The output power of a solar panel array can be monitored by specialized software and viewed at a distance using an app or used as input to a smart energy management system.
Is anti-reflective coating worth it?
Shiny surfaces reflect the various wavelengths in sunshine to various degrees. Not all wavelengths are converted into electricity with the same efficiency. Anti-reflective coatings that serve to absorb the most efficient energy converting wavelengths are worth the cost, as they can recover up to 3% of the solar panel’s lost power due to light reflection.
Is solar tracking worth it?
Tracking costs are reducing and now add between 10 to 15% of a ground-mounted solar panel array. Even single axis solar tracking is worth the extra cost as up to 30% extra power can be recovered using this technique.