The advantages of using dry ice blasting to clean solar panels over pole fed pure water systems

A month ago i talked about a series of tests Optimum have been commisioned to carry out at a Solar Farm.

My previous blog describes the task in more depth, but here is a brief synopsis; a client is becoming concerned that, after cleaning of their solar panels had been carried out (by pole fed water and an industry standard solar panel cleaning chemical), the output of the solar panels rapidly diminished. Usually after 3-4 days the array could lose up to 5% of total output  and after 1 week be back to around a 7% loss of output (the point at where output loss was before cleaning). Below are the results so far:

The array is made up of 11,300 245W panels and our test results after 1 month are as follows:

• kWh loss before cleaning work takes place = 840kWh per day

• kWh loss 4 days after pole fed water+chemical = 227kWh per day
• kWh loss 4 days after dry ice cleaning = 87kWh per day

(There is no scientific evidence to prove that all solar panels would lose output in such a short period. Lots of factors come in to play such as weather and location to other airbourne contaminants, this particular test was run in July 2013, conditions were very dry and hot. The main source of airbourne pollutant is from an adjacent cattle farm and a major motorway) 

The results show that there is a significant slowdown in the build up of contaminants after dry ice blasting is performed. Does this equate to savings? If you analyse the results in terms of every kWh lost from output as being directly linked to energy costs, then yes, dry ice blast cleaning is more cost efficient.

But, as i mentioned on a previous blog, dry ice  will not compete with water+ chemical on price. To clean 11,300 panels with dry ice will work out to be nearly double the cost. What we are trying to ascertain from these test results is if the cost of dry ice blast cleaning can be offset by 1) less frequent cleaning schedule due to a slower build up of a contaminant and 2) is the output/production increase, whilst the contaminant builds up, financially better during the time it takes for the panels to reach a 840kWh per day loss.

We do know that dry ice cleaning is a better solution in fully removing the layer of bio film that attaches to solar panels. If the bio film isnt removed, in its entirety, then pollutants easliy stick back to the surface and production is significantly reduced in a matter of days.

It will be interesting to see how long it takes for the kWh loss per day to reach 840, the point at where the test started!

It has been great to be involved in the tests and Optimum Dry Ice Blasting would like to thank Trevor Brierly and his team for all of their input.

Second round of results to be posted soon!

By Ian Reynolds