Every day they're using 20.7 litres of water to keep a single panel clean. It's an interesting problem, but I'm certain there's a better way if one were willing to develop better automation.
> It required one litre of water to clean, each of 400,000 installed panels. A total 15 days cleaning cycle required, 124 million litres of water enough to sustain 9000 people, while rain in Cholistan desert is rare and far between. Providing such huge amount of water in desert terrain, became a challenging and daunting task for management team. Besides, the manual cleaning methods allowed setting of dust before it was re-cleaned.
"putting on a pair of work shoes and getting out the ladder once a week/month to polish the mirror hardly seems like a downside"
I also wonder about why cleaning isn't a solution but, if it is to be a solution, then that solution must be automated.
An automated system would be cost effective, dependable and conserve water. In the hottest places, where water is naturally scarce, the water would need to be reclaimed, filtered and reused in an efficient manner.
In some areas, the water use just from cleaning solar panels becomes a serious issue (let alone using more water to cool them). It's not much water to spray on some panels you are experimenting with, but for a large installation it seems like it would be a lot of water.
"Just" a matter of distilling it? Have you ever looked at the sheer amount of water entering and leaving a water cleaning plant? It's not a matter of having the technology, but of doing it at scale.
What they did is explained here, the process is quite involved:
> Each of the 400,000 installed panels required one litre of water to clean. A 15 days cleaning cycle required 124 million litres of water (enough to sustain 9000 people) while rain in the Cholistan desert is rare and far between. Providing such huge amount of water in desert terrain, became a challenging and daunting task for management team. Besides, the manual cleaning methods allowed setting of dust before it was re-cleaned.
Reminds me of newer appliances (such as washing machines/toilets) that brag about water efficiency yet don't do nearly as good a job, requiring a second cycle, thus using more water.
"When one end of the panel is placed in dirty water, it draws a thin layer of water upwards, which evaporates in the sun, purifying it. By placing the panel inside a glass box, the team collected the evaporated water for use, separating it from the dirty water with a layer of insulation."
3 cm^2 of the material produced 5 ml of water in 2 hours. They don't say what it cost to make.
Not for the people who would have liked to drink the water used to clean the panels (cf the projects in deserts). Everything has some drawbacks and it s useful to diversify.
Nice. I've tried searching for it before but clearly didn't get the right combination of keywords. Mostly I've found people using the waste water to pre-heat the supply (which itself is a good idea but doesn't solve the water capacity problem).
20 watthours per liter of drinking water is not bad and it's way more efficient than the dehumidifiers. Looks like a great solution even at that slow production rate.
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