Future-Proofing Solar Farms with Advanced Cleaning Technologies – Arpit Saxena VP- Sales and Business Development Skyfri Energy Private Limited

Why is Solar Module cleaning essential for Solar Operation and maintenance?

Solar modules require regular cleaning so that soiling does not affect the energy generation adversely. Usually, PVYSYST simulation accounts for up to 2% for soiling depending on geographical location, the climate pattern (including the extent of rainfall) and the environment. However, in the tropics, maintaining dust-free panels can be a challenge. A clear maintenance program that includes periodic cleaning is necessary.

What are the conventional methods available for Solar Panel Cleaning?

Wet cleaning is a preferred choice as it ensures better control on the soiling by removal of stubborn dirt, grime, and bird droppings. The question that arises is how many cycles of wet cleaning need to be done to keep soiling at bay? To be on the safe side of managing costs of wet cleaning and the risk of generation loss, developers usually fix 12-18 cycles of wet cleaning a year. This has become a de facto norm in the industry. Is it there to stay? Well, there are other options that are worth exploring as wet cleaning is all centered around water and its availability, hardness and the costs involved. Dry Cleaning may be the choice going forward or hybrid approaches of dry and wet cleaning during different periods in future.

Dry cleaning of panels does not require elaborate planning and transportation of water. Manual cleaning using Microfibre cloth and well-designed soft nylon bristle brushes can ensure effective cleaning without damaging the panels.

To have a better control on Soiling, the need is to reduce the dependence on labor and look for water less solutions; Semi-automatic and automatic robotic dry-cleaning techniques fits the bill and have picked up momentum. It has become an inherent part of design and planning when it comes to installing large Solar Farms or Solar parks-the switch to dry cleaning using robots is evident. Moreover, this is a well-suited option for arid regions where water is scarce. Dry robotic cleaning works for frameless Thin Film modules as well and since the percentage of Thin Film Modules market share is (especially Cadmium Telluride (CdTe) Thin Films) is growing, robotic technology should be adaptable for all kinds of modules and for commercial and residential installations.

What are the risks associated with Dry cleaning?

With the solar portfolio tremendously increasing since the last decade, there will be challenges of scarcity of water to reckon with for seamless wet cleaning. Dry cleaning option will always motivate us to save groundwater; however, there are always pros and cons for any technologies.

In Manual Dry cleaning, there is always a risk of irreversible scratching, which cannot be avoided as the labor involved in cleaning can have varied approaches to cleaning. The chances of abrasion are higher while doing dry cleaning and can impact the Anti reflective (AR) coating particularly.

Dry cleaning is inefficient for cleaning bird droppings. Also, the cost of solar modules is 40-50% of the project cost, which needs to be protected from micro scratches. Any single micro scratch shows its major impact on generation after 3 -4 years of dry-cleaning/robotic operations.

Dry cleaning also has constraints for the projects that are having Land undulation and array misalignment as it creates a bigger challenge for Dry cleaning bot operations.  

Recent Research on aspects of vibration shows  that wind vibration effects on modules can potentially have more impact on Solar panel integrity than due to vibrations during module cleaning. So Robotic cleaning is a safe option with no direct human contact while cleaning. So, shock hazards are practically negligible.

What are Skyfri’s experiences that they wish to share with a robotics manufacturer?

Since dry cleaning has certain limitations compared to wet cleaning, the option of using robots with rotary cleaning brushes along with water spray nozzles will help. This will give a right balance to clean as much as is required and to top it up with water cleaning to channelize the dirt away completely.

While using Robots for cleaning, a few points to bear in mind are

1. whether the manufacturer has sought NOC from panel manufacturer (for warranty and safety of module) before usage to ensure warranty coverage on their modules
2. The load on the modules while cleaning needs to be uniformly distributed – erratic movement of the robot can impact the load-bearing on certain sections and cause damage
3. Impact of vibration on modules in the long run?
4. Proper selection of the dry cleaning robots to meet the specific site conditions

What does Skyfri think about the future of solar panel cleaning?

To protect the modules & achieve minimum soiling losses, further new technologies have evolved and may be commercially available in future, which will provide water-less and contact-less solutions using electrostatic repulsion to remove dust off the panel.

Last but not the least, Sustainability is an area in which Robotic cleaning will score – no use of water while doing dry cleaning, one can program for as many dry-cleaning cycles as required and limited water usage while doing robotic wet cleaning. Water usage can be drastically reduced and thereby provide a boost for water conservation measures.

We can thereby aim for the 3 S’s of Soil-free modules, Sustainability and Safety through Robotic Dry-Cleaning practices. In future, with all the AI advancements, robotic cleaning can be smarter and more cost effective and decide for us whether cleaning is required or not on a particular day – whether wet or dry and it will weigh the cost -benefit analysis as well.