Just doubled my solar output with $1 mylar

[swbluto]

I created a reflective surface using mylar from a $1 emergency space blanket (Found on ebay) and some cardboard laying around, and I just nearly doubled my solar panel's output at 9:00 a.m. in the morning from 20 watts standing by itself to 35.5 watts with the reflectors around it (The solar panel angled towards the sun, and the reflective surface angled to maximize the reflected solar rays onto the solar panel). I just nearly doubled my solar panel's daily output with $1 in material and made them actually pretty useful even in the wee hours of the morning, so I'm pretty pleased. My design looks like a flower design with the solar panel in the middle and four reflective surfaces angled at the sides of it: Methinks flowers were onto something, lol.

My panels are 20% efficient SunPower cell based and it's rated at 30w (I'm using for experimentation), and I'm usually able to get 27 watts at high-noon (around 1:30 p.m. in recent days). So getting more than that rating at 9:00 a.m. with some cheap materials is pretty nifty.

 

[KMB]

interesting...Pic?

 

[swbluto]

Here's my simple test setup using some cardboard boxes hanging around. I used normal elmer's glue to attach the mylar to the cardboard and tried to press the mylar as flat as possible against the cardboard to remove the airbubbles.



Apparently hydroponics enthusiasts and the such have been using reflective mylar for years to boost solar output to help their plants/vegetables grow. Seems like it works quite well on solar panels, too.

The amount of people claiming this idea wouldn't work online dumbfounds me. I'm guessing they're trying to suppress 'new ideas' as a way of exerting their power in enforcing 'normalcy' by only allowing 'normal ideas'. When the expenses are like $100 panels vs $1 for mylar, my financial calculus doesn't care about the idle speculation of armchair 'experts' on the internet, lol. One experiment is worth more than a thousand opinions, in my humble opinion, lol.

The one caveat is that the solar panel temperature raised from 106 degrees to 120 degrees at 9 in the morning, so there's probably a limit to how much you can amplify the sun before cooking the cells. That'd require some testing to figure out those limits. Since solar cells are made of silicon, they're probably like most silicon devices and can go upwards of 200+ degrees fahrenheit, though it'd probably shorten their lifespan. By how much, I don't really know. Anybody have spec sheets on solar cell temperature and solar cell lifespan?

 

[bowlofsalad]

I was under the impression this was a bad idea as it will cause the panels to get much hotter, shortening their lifespan.

 

[swbluto]

I was under the impression this was a bad idea as it will cause the panels to get much hotter, shortening their lifespan.

At 110 degree ambient in the middle of california at highnoon, it's probably a bad idea. At 11:00 a.m. in the middle of Alaska on a cold wintry morning, probably not so much. And, then there's probably lots of variation in between.

In particular, solar boosting during the morning hours and evening hours, which comprises over 60% of the day and most solar panels are putting out far below their rated output at those times, probably isn't a bad idea. It's definitely a lot cheaper than ordering more solar panels, lol. And, it'd probably help to boost solar output during cloudy conditions when output is usually halved.

Now, I just need to source some bulk quantities of corrugated plastic to start producing these things en masse, lol.

 

[torker]

Also if you haven't ,raise the panel up a few inches for cooling. On my new favorite website. Except my homepage ES of course :} ) http://forum.solar-electric.com/forum.php I have learned how much temp. affects power output so much that folks have to be careful about running their charge controllers too close to max . In the winter amperage goes up considerably.

Good result and experiment btw..

 

[amberwolf]

I suspect that almost anything you can do that will increase the right wavelengths of light to input to the collector would help it's output--but if you can heatsink the back of the panel in some way to get rid of the excess heat, if there is any, it would probably help it's efficiency. In your case, I doubt it's much of a problem (it certainly is here!).

FWIW, if you want another source of mylar, you could also recycle snack bags and whatnot that people throw away. Many of them have reflective mylar on the inside, and if they aren't crumpled up when tossed out then they could easily be flattened and glued down to a stiff flat surface to ease making reflectors out of them.

A source for coroplast is all the election signs that get put up around cities, if you have any near you. After the election they're usually just trash.

But the basic idea of the mylar on your panel is a little like what I do with my solar water heater tank. I have a flat wall-type mirror that's something more than 3 feet on a side, that leans on a shed wall behind the tank, angled to reflect morning sun onto the tank. I've not checked it at all the hours so far, but AFAICT from what I have seen it works for at least 2-3 hours to keep sun shining on the "back" and bottom of the tank, and it most definitely decreases the time it takes to heat the water for a shower. I don't know that it comes even close to doubling the energy input ot the tank, but it is probably 10-15% more than it would otherwise get, at a guess, based on surface area of the mirror vs tank vs sun angles.

Probably painting my tank black would help more, and building a box with "parabolic" reflector at the bottom/sides, and transparent cover that acts as a "solar oven" would help even more, once I get around to that.

 

[swbluto]

I suspect that almost anything you can do that will increase the right wavelengths of light to input to the collector would help it's output--but if you can heatsink the back of the panel in some way to get rid of the excess heat, if there is any, it would probably help it's efficiency. In your case, I doubt it's much of a problem (it certainly is here!).

FWIW, if you want another source of mylar, you could also recycle snack bags and whatnot that people throw away. Many of them have reflective mylar on the inside, and if they aren't crumpled up when tossed out then they could easily be flattened and glued down to a stiff flat surface to ease making reflectors out of them.

A source for coroplast is all the election signs that get put up around cities, if you have any near you. After the election they're usually just trash.

But the basic idea of the mylar on your panel is a little like what I do with my solar water heater tank. I have a flat wall-type mirror that's something more than 3 feet on a side, that leans on a shed wall behind the tank, angled to reflect morning sun onto the tank. I've not checked it at all the hours so far, but AFAICT from what I have seen it works for at least 2-3 hours to keep sun shining on the "back" and bottom of the tank, and it most definitely decreases the time it takes to heat the water for a shower. I don't know that it comes even close to doubling the energy input ot the tank, but it is probably 10-15% more than it would otherwise get, at a guess, based on surface area of the mirror vs tank vs sun angles.

Probably painting my tank black would help more, and building a box with "parabolic" reflector at the bottom/sides, and transparent cover that acts as a "solar oven" would help even more, once I get around to that.

That seems like an easy problem to solve. Just immerse the solar cells in shallow distilled water and you got instant cooling. One could probably increase the maximum power output of the solar panels even more with that setup. If one were in a desert, than tapping a cold 'heat sink' underground would probably be the most effective way to get cost-effective 'cooling' (Running pipes undeground to extract the coolness).

Then again, if it's completely zero humidity in your area, then sufficient shade might be able to do it for cooling.

You could also take advantage of the heatsink of the desert during the nighttime when it's cold as an effective coolant. Expose the water/fluid to the cold area in the most effective way possible (Spread over a large area, actively cool it by fanning it) during the night time, and then shutter the water in a large well-insulated tank during the day, possibly buried underground for enhanced cost-effective cooling.

 

[Dauntless]

http://www.solar-tracking.com/

I say you should just drain that heat right off there and turn it into more electricity.

http://www.ebay.com/itm/like/271567957772?lpid=82

 

[Chalo]

I say you should just drain that heat right off there and turn it into more electricity.

http://www.ebay.com/itm/like/271567957772?lpid=82

That kind of presumes you have a "cool side" for your Peltier junction. Here in central Texas this time of year, the only cool side of anything is either expensively air conditioned or spring-fed.

 

[torker]

I have wondered about the nightime in the desert. Does it only get cool/cold at night in the winter ? Ks is like Tx I presume. Still 80s at night most summers.

 

[amberwolf]

Depends on where in the desert, and the current humidity level and any cloud cover.

Here in Phoenix, we often get raised humidity and/or cloud cover at night (not being "burned off" by the sunlight anymore), so it stays warmer than it would otherwise.

But there can easily be a 30-45F difference between high and low temperature in a day, if humidity is low and we don't get cloud cover at night. So if it's 105F daytime, it could get down to 60-75F at night (doesn't usually in this season in the city, but it might out in the actual desert itself, far enough from the city's environmental disturbance. Right now it tends to be in the 80s F lows, and 100s F highs).

If there's significant wind, it could get cooler faster, if there's evaporation like here in the city off of trees, lawns, etc.


Even so, below ground it's in the 60s F not that far below the surface, and tends to stay that way day or night even in summer.

 

[Dauntless]

I say you should just drain that heat right off there and turn it into more electricity.

http://www.ebay.com/itm/like/271567957772?lpid=82

That kind of presumes you have a "cool side" for your Peltier junction. Here in central Texas this time of year, the only cool side of anything is either expensively air conditioned or spring-fed.

My first presumption is it doesn't have to be a dramatic difference. Since the danged part in the Sun is just going to keep heating back up, you have a perpetual current flow. This will limit just how hot it gets, but it'll remain hot.

My second presumption is it'll be convenient to shade what is necessary to make this work. That makes a huge difference. BUT people make peltier coolers for their drinks. You can also use it on expensive electronic equipment. https://tetech.com/peltier-thermoelectric-cooler-modules/?gclid=CLC9qvWwvsACFUJqfgod0gwAKA

 

[Chalo]

I say you should just drain that heat right off there and turn it into more electricity.

http://www.ebay.com/itm/like/271567957772?lpid=82

That kind of presumes you have a "cool side" for your Peltier junction. Here in central Texas this time of year, the only cool side of anything is either expensively air conditioned or spring-fed.

My first presumption is it doesn't have to be a dramatic difference. Since the danged part in the Sun is just going to keep heating back up, you have a perpetual current flow. This will limit just how hot it gets, but it'll remain hot.

I suppose it would not take much solar electricity to run a small pump to recirculate evaporatively cooled water against the cool side of the Peltier junction. I wonder if there would be a net gain in that case or not.

 

[dnmun]

of course not.

you can refine the idea of using the mylar by using some thin hardboard and curving the hardboard into a catenary arch with the mylar bonded smooth to the surface.

you can model your catenary arch by using a string suspended from the ends and then trace the catenary curve onto a sheet of paper alongside the catenary string. then use that pattern to hold the hardboard curved to the catenary bowing.

cut the catenary arch in the middle and mount each section on each side of the solar panel and then adjust the specular reflection from the mylar so it covers the entire surface of the solar panel. do this along both of the axis, the corners will not matter but the catenary arch will spread out the specular reflection so it is fairly uniform across the entire panel.

heat is not an issue until you reach high power levels and since the light hitting the solar panel is already a specular reflection the amount of heat that will be reflected to the solar panel will be insignificant and the infrared will be absorbed by the mylar to the largest extent.