Diesel-Killing DIY Solar Tracker Boosts Efficiency 30% & Filters Water, Too
Solar is in a desperate race against diesel when it comes to supplying electricity to off-grid communities, and SunSaluter is in it to win. SunSaluter, organized as a nonprofit, is pitching an “ultra low-cost” do-it-yourself solar tracker that uses the ancient tools of water clocks and gravity to produce a 30% gain in efficiency, while also producing approximately four liters of clean drinking water. The last time we saw a diesel generator produce clean water and electricity from the same output was…er…well….
Birth of a Nonprofit Solar Tracker Organization
The last time the SunSaluter solar tracker crossed the CleanTechnica radar was back in 2011, when the solar tracker was barely out of the brainchild phase (though, sister site Solar Love covered it a bit in May, and we reposted that piece). The inventor, Eden Full, was a 19-year-old Princeton University mechanical engineering student in 2011, but the device — which is available for purchase as a DIY kit — was already garnering attention, including a $275,000 prize in the 2011 Postcode Lottery Green Challenge, among others.
The icing on the cake was a a $100,000 fellowship from the Thiel Foundation (as in PayPal cofounder and early Facebook investor Peter Thiel), which provided Full with an opportunity to pursue development of the solar tracker full time while networking with entrepreneurs.
At the time, CleanTechnica noted that Full was developing the product for her company Roseicollis Technologies, but it seems that the allure of doing good was too strong to resist, and now we find the “proudly Canadian” Full helming the SunSaluter nonprofit as founder and CEO.
The SunSaluter Solar Tracker — How It Works
Fast forward to 2015, and Full’s SunSaluter has been deployed in 16 different countries, racking up the aforementioned 30% gain in efficiency while providing clean-sourced electricity (and clean drinking water) for 8,000 people.
Here’s the pitch:
The SunSaluter is an ultra low-cost, passive, single-axis solar panel rotator (called a tracker). The SunSaluter boosts energy output by 30% by keeping a solar panel oriented towards the sun throughout the day. With improved efficiency, fewer solar panels are needed, and the overall cost per watt of solar energy is reduced. Conventional solar trackers use complex electronics which make them more than 30 times as expensive and prone to failure. That’s why solar trackers have never made sense for the developing world – until now.
The SunSaluter is a flexible system that can be retrofitted onto any solar panel without using special tools. You simply mount the solar panel on a rotating frame and suspend a weight at one end.
The secret sauce is the weight, which is a simple outflow water clock. Water clocks were one of the first time pieces, consisting of a container that lets water drip out at a steady, controlled pace.
In the SunSaluter system, as the water drips out, the weight lightens, and the panel rotates on the frame to follow the sun (solar panels need to be kept at or near an optimal angle throughout the day in order to function at peak efficiency). The rate of drip can be easily adjusted to control the rate at which the solar panel moves.
Of course, a wide variety of solar trackers are already on the market, but upfront expenses and maintenance issues make them impractical for off-grid use in underserved communities.
Modern solar trackers also do not generally include a water-purifying component.
Go Ahead, You Know You Want To Do It
As a nonprofit, SunSaluter is in the business of providing affordable, sustainable electricity to off-grid communities. Estimates vary, but according to SunSaluter, that means 1.5 billion people, with an overlapping clean water access issue that affects 750 million people — 100 million in India alone.
In the past, cheap diesel generators led the few options available, or kerosene lamps for lighting. Now, solar is emerging, but SunSaluter makes the point that solar panel technology is still too expensive for many communities.
The SunSaluter helps to chip away at that barrier, by enabling communities to squeeze more electricity out of the same panels, or conversely, to buy fewer or smaller panels.
SunSaluter’s simple water purification system also provides a solution to cost and maintenance issues that bedevil conventional systems:
Existing water purification technology is highly effective at preventing the transmission of waterborne pathogens, but the majority of clean water programs still fail due to improper operation by end users. Standalone water products are only 6% to 27% effective at reducing diarrhea. There is a dire need for products and approaches which improve user behavior and uptake of these clean water technologies.
That’s where you come in.
SunSaluter is currently enlisting entrepreneurs and business partners to help it with the marketing and manufacturing end, and you can also chip in with a donation to the nonprofit.
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Image (screenshots and photos) via SunSaluter.
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It needed recalibration every week. Just like drip emitters, the drip line emitters will get narrower or clogged thru time and the flow rate changes. But it is still cheaper to recalibrate by continuously adjusting the flow rate based on previous day’s performance. So the rate adjustments better be user friendly and heavy duty.
A wind break would further add to the complexity and cost of installation. Chances are that the reduced air exchange would also slightly increase the temperature of the solar panels, thus reducing their efficiency. The wind issue certainly poses a big challenge…
Designed for third world countries where labor is cheap, so the recalibration is not a problem… not really useful in the developed world.
How does the water purification work?
The problem with any tracking mechanism is matching the great reliability of static panels. These will keep working for 30 years with only occasional washing to clear of the dust and replacing the inverter in mid-career. Any mechanism will need a lot more care and attention. It’s very hard to ensure this in Africa. Eventually it will just be cheaper to instal more fixed panels. Perhaps it is already.
Ultraviolet rays penetrate the plastic through the course of the day and destroy any pathogens. Doesn’t do anything for metals or inorganic materials, but works wonders in avoiding cholera, dysentery, etc.
Single axis trackers are really rather simple – their only moving part is a simple electric motor, which is robust (there are plenty of appliances over 30 years old that still work) and easy to repair for someone with a few hours of training.
IHS and other analysts are bullish about the simpler single axis designs that have appeared over the last few years. SunPower and other majors now offer them as a default option in their turnkey systems.
http://m.pv-magazine.com/news/details/beitrag/ihs–global-single-axis-tracker-revenues-to-reach-2-billion-in-2019_100018728/
http://us.sunpower.com/utility-scale-solar-power-plants/oasis-power-plant/
The main manufacturers of single axis trackers (First Solar, NEXTracker and others) all promise 25% gains. This presumably simpler and less finely controlled tracker claims 30%. I’d like to see some data on that…
Part of the increased efficiency might be taking into account the filtered water as a product. You know how the overall efficiency of residential Fuel Cell Electric generator can get as high as 95% because they use all the waste heat for heating.
“… to produce a 30% gain in efficiency, while also producing approximately four liters of clean drinking water”
English is not my first language, but to me that quote sounds like they promise 30% efficiency gain on top of the water production. Why use the conjunction ‘while’ if the water is already meant to be included in the 30%?
The efficiency of the cell is not increased per se…it’s still only going to convert the same amount of non-concentrated sunlight per unit of surface area, ie. 20% +/-. By using a tracker, you improve the hours of direct rays collected/trapped, thereby improving the total amount of energy, but it will still only generate the amount of energy it’s rated at.
Same thing goes for concentrated solar; more light is directed at silicon/whatever material. The PV panel is still onlly going to at best collect the same 20%+/-, there’s just more photons to get it from. Thus you’ll harvest more light per given area of panel coverage and thus more energy, but the PV panel will still only convert the same % of light to energy. Considering the extra heat on an un-cooled panel, I presume that the efficiency of the panel would actually decrease, no?
The efficiency of a sell does not increase, but the amount of energy generated per unit of land used does increase. That’s another definition of efficiency, one that looks at a system level rather than cell level. ‘Efficiency’ is a really vague term, as you can define it at pretty much any level from micro to macro scale.
All that’s not the point I was trying to make though. That was simply that makers of more advanced trackers only claim 25% more energy per unit of land (which is already on the more optimistic end of the scale), whereas these guys claim to be able to do even better. Red flag if you ask me.
Sounds like winding the old cuckoo clock instead of hitech gimmickry.
I can dig it. Doesn’t need to exact, does it. Good enough will do. In this case, no need for fancy gears, either. I like it.
It would be useless when there is wind. If it can move by the slightest weight difference, it will easily be disturbed by the wind.
Are you sure Marion? From the picture, you are correct. But I can imagine using a simple screw gear would solve that. OK, one gear. I think really, what we are tailing about here is that its simply a crude clock. A water clock. Any clock mechanism will do, really. Small errors don’t matter. The improvement in efficiency is great compared to not having it.
Biggest costs are the frame, pivot, and screw gear. Any wind up clock could do it. Some have preferred a differential sensing mechanism instead. I prefer low tech. Simpler is better.
Wouldn’t the water bottles provide enough weight to anchor the panels?
As far as I can tell from the diagram, The weight difference is between the counterweight and the water to be purified.
Having turned panels with a simple push of the hand for several years, this what I learned. With only three abrupt turns a day the result is very close to a continuous tracker. Adjust the seasonal tilt twice a year and you get close to a two axis tracker. The farther north you go (I am at 51 degrees north) the less difference east west tracking makes in winter. In summer the difference can be 30% or more. Trackers are generally too expensive. They need absolute simplicity like a mechanical arm that moves 3 times a day. Just buying more panels with a seasonal tilt adjustment is cheaper than a tracker.
Yep. In some countries, many countries actually, it is cheaper to adjust panels by hand through the day rather than pay for automatic tracking. Of course, idealy we want the cost of tracking to come down and the cost of wages in those countries to go up so this is no longer the case. But that might take a while, so there is plenty of oportunity for this kinds of hands on work. Tracking is starting to become the norm for utility scale solar because as solar penetration increases the price of electricity tends to be lower around noon than in the hours after sunrise and before sunset. But perhaps we will give up on tracking for utility scale solar, at least in low to mid lattitudes and just install bifacial solar panels that are glass on both sides and generate electricity from sunlight hitting one side in the morning and the other side in the afternoon.
This seems absurdly stupid.
Surely stepper motors off a raspberry pi would be a hundred times cheaper.
And with solar so cheap now why bother tracking at all?
Yes from our place of privilege in a developed country the mechanical setup you mention would be cheaper and easier, but that isn’t who these are designed for. Someone in a home or village hundreds of miles from the grid and internet access in undeveloped parts of Africa need a device like this. Incomes that are only dollars or pennies per day mean that buying solar panels or panel are a major investment on par with our purchasing a new car. So adding a tracking function that other than the osmosis tubing can be made with found items (water jugs and cord to attach them) is very helpful for someone in this situation. And allows the family to stay working in the fields and come back to clean water while generating the maximum power from their purchase .
I tried one a few years ago when they were in their test phase and it was quite effective during the summer, but did have problems during the winter from freezing up, this won’t matter to people in equatorial regions though.
Yes panels are now cheap enough that I just buy extra to orient to the east and west, or could make mechanical trackers, but this doesn’t apply to everyone around the world, and that is who this style of tracking is for.
I look at the plastic water containers and I immediately think they will not last long. I also think of algae buildup. And wasted water. And all the mickey mousing about that will be much more expensive than some automated process. I suppose I need to actually see them in operation like you have to really understand.
There will be less need for seasonal adjustments in equatorial regions as well.
Another problem with a single-axis tracker, pivoting on a N/S axis, is tilt. Near the Equator you needn’t bother but anywhere else you need to tilt on the other axis. This is fine for conventional designs but would be trickier with water counterweights.
All in all a continuous screw, a hand crank, and a small boy to turn it three times a day gives you a lot less to go wrong.
Yes, if we are talking village economics, a simple push of the hand 3 times a day is good work for a boy or girl. It takes 5 seconds. I did it for years…great right arm exercise! These days it is unnecessary since as we increase the size overvproduction is the result off grid.
What if the water was added to the top of the unit, and the runoff was used to cool the unit to increase PV efficiency?