Should I clean my Solar panels this summer?

Should I clean my Solar panels this summer?

If you undertake a google search for "should I clean my solar panels?" you'll be directed to many sites indicating various claims of potential gains from cleaning your solar array.  I'm here to lay down some facts based on research, not ambiguous commercial interests pulling at your wallet.

Ok, let's get to it.  From my first google result, I jump right into this claim.

The claim: Cleaning your solar array could amount to 30% gains in performance.

Fact or fiction?
Let's begin with the type of dust and its impact.  A review undertaken in 2016 on the soiling of solar panels (aka crud on your solar) found there are a series of environmental and location & installation factors which result in dust landing on your solar array.  

Source: Adapted from this paper

This tells us there are so many variable factors which can influence the impact of soiling on your solar array.  This same review paper found "technically, dust reduces output power from PV between 2% until 50% in different area[s]."  

The most critical and variable factor is geography and climate - where the solar array is located. This same review paper found "Middle East and North Africa have the worst dust accumulation zones in the world".  

Source: Dust intensity worldwide

Another paper published graphically displayed the impact of cleaning solar arrays on the overall capacity factor.  

Source: From this paper

The detailed results found that fixed install solar panels in Australia could gain the following efficiency increases from soiling impacts at cleaning intervals of;

  • Always clean - 6% (warning: may require obsessive cleaning)
  • Weekly - 6%
  • Monthly - 5%
  • Quarterly - 4%

Results from further studies indicate similar results. Oh and this one too.

Again these results do not consider in all the factors listed above.  Tilt and orientation can play a significant role in determining the impact of soiling on your array.  For example, flat-installed arrays will suffer from greater efficiency impacts than those tilted.

Conclusion: Although many claims of improving solar panel efficiency by cleaning regularly are true, it is only true for geographical locations where a combinations of factors result in high soiling (Egpyt, Saudi Arabia, Iraq, Algeria for example).  For most Australian installations, you are likely to see a small degradation in performance over the course of a year.  

Ok, so how do I go about cleaning my solar panels? You've got a few options here.

  1. Do nothing + the rain - yep it's cheap and free but can be seasonally volatile.
  2. By hand - a brush and a hose with gentle detergent (approach with caution - water + roof). No pressure washers, they can break the seal around the frame.
  3. Third-party - you can find a contractor by googling "mobile solar cleaning" and paying some monies.

There you have it, a level-headed approach to this little issue of cleaning.  I'll leave it for you to make your own decisions on cleaning.

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