Reading value from Solar Panel Cell, current peak concern

[(*steve*)]

Solar panels may be more efficient in colder weather, but there's less sunlight available.

An edge effect of clouds magnifying sunlight might be an hypothesis, that attempts to explain observed behaviour, but it's not correct AFAIK.

You can achieve higher power output from a solar panel by cooling it, and panels get hot when exposed to sunlight. This explains why panels suddenly exposed to fill sunlight will generate more power than they do in the steady state condition.

Wait for a sunny day. Graphs like you have produced recently are not atypical of what I see on a much larger scale array on very overcast days. Data for a sunny day will be more helpful in determining if you're getting a reasonable looking graph.

 

[ge96]

Yeap another cloudy day...

Good ol' angle of insolation I think, isn't that neat I think the Earth is farthest from the sun during summer time, could be wrong.

edit: guess it depends whose summer

Yeah I'm waiting for a nice sunny day.

 

[ge96]

I don't understand it seems to be peaking at 0.18V it was higher than that yesterday but didn't surpass 0.4V it's almost noon, will see. Granted sun's path is going orthogonal to the panel's face.

 

[(*steve*)]

You need at least one reading at close to midday with a clear sky with the sun casting light normal to the front surface of the panel..

However, it is possible that the specifications of your solar panel are a little exaggerated, or even that your 270Ω resistors are a lower value.

Do you have a multimeter? Can you measure the value of those resistors? Another alternative is to tell us the colour of the bands.

 

[ge96]

I measured them all they're 330 Ohms (with a multimeter)

Actually it occurred to me that my window has an overhang and also the sun passes across and not towards my panel (not sure how much of a difference that would make). Mostly though when the sun was most intense my panel was in a shadow.

I'm going to reposition it for tomorrow.

Edit: We're thinking of putting a servo or two on the panel(s) and having it adjust to the sun's direction throughout the day, throw some ML on there, why not... (I don't even think it's necessary).

One thing to consider though is seasonal history of sun direction and then using that and say a compass to position the panel.

I'll also expand the API for multiple readings as intended and hopefully when my roommate sets his up I'll get to store his data haha.

The time scale is messed up, still figuring out how to use this chart script. That's just incrementing the samples, I have the x-axis actually set to time but yeah not correct at this time. Samples are from 8 AM to 7 PM

 

[hevans1944]

270 Ω and 330 Ω are both standard values for resistors. Color code for 270 Ω is red-violet-brown. Color code for 330 Ω is orange-orange-brown. Use your multimeter to measure the parallel combination of your seven resistors instead of just one of them. That will tell you whether you have any cold (high-resistance) solder joints.

Panel tilt and the orientation of the plane of the panel is very important to collecting sunlight properly. Tilt angle is a function of your latitude and the time of year. A line perpendicular to the plane of the panel should point true south. Lots of nifty information on the World Wide Web about how to orient a solar panel for maximum efficiency. The "best" designs use motors and a sun-sensor to move the panel into an optimum position. You can probably just mount your little panel on a camera tri-pod and orient it with you Mark I Eyeballs. Problem is, the optimal orientation changes continuously throughout the day and the year, which is not ideal for comparing readings between summer, fall, winter, and spring. But, solve one problem at a time. I can't believe you are taking readings from a solar panel that is partly shaded during some portion of the day. What's the point of doing that?

 

[ge96]

That will tell you whether you have any cold (high-resistance) solder joints.

Panel tilt and the orientation of the plane of the panel is very important to collecting sunlight properly. Tilt angle is a function of your latitude and the time of year.

What's the point of doing that?

Cold solder joints, I twisted them together... going point about measuring them together.

Good tip on the angle, one problem is I'm in an apartment complex and I can't exactly position/place the panel as freely as I'd like to my roommate has a ledge on his window so he can actually get sun.

It was accidental it didn't occur to me that this giant overhang thing on the window would block out the sun after say 10 AM due to the shadow I just saw it yesterday looking from outside of the house. So I moved it for tomorrow a little lower but still probably going to be blocked, not sure what to do at this point.

The wifi is really strong though, I can get signal from like 300 feet away or something so possible I could set it up to be battery powered and hide it (the raspberry pi) and still get the data.

 

[hevans1944]

I don't suppose you have access to the roof of your apartment building... roofs are good places to mount solar collectors.

 

[ge96]

I don't suppose you have access to the roof of your apartment building... roofs are good places to mount solar collectors.

Haha probably not "Get down from there you lawsuit waiting to happen!" haha

I could share the ledge with my friend possibly. I don't know, it's a cool project/got exposed to ADC/how to measure stuff/setting up the site. I would like it to continue but would suck if the data is not great because of the shadow.

Anyway I moved it lower to get some better data but will probably be the same. Around 2 PM or so yesterday the shadow extended past the window sill (below) so the solar cell was in a shadow.

 

[BobK]

The whole positioning to be perpendicular to the direction of the sun thing sounds good, until you work out the details. A full 2-axis positioning system gives you about 30% more energy over the day than a fixed panel optimally positioned for the latitude. It is typically cheaper to buy 30% more panels instead of all the hardware to position them. Which is why positioning systems are rarely seen even on large solar farms.

Bob

 

[ge96]

The whole positioning to be perpendicular to the direction of the sun thing sounds good, until you work out the details. A full 2-axis positioning system gives you about 30% more energy over the day than a fixed panel optimally positioned for the latitude. It is typically cheaper to buy 30% more panels instead of all the hardware to position them. Which is why positioning systems are rarely seen even on large solar farms.

Bob

Ha that's funny practicality over cost or what's the term.

I did look up "omnidirectional panels" just for kicks interesting

A hemisphere design that could also focus the light I don't know... interesting stuff.

 

[hevans1944]

The solar hot water heating system I saw in Tucson, AZ, back about 1979 or thereabouts, wasn't terribly sophisticated. It did use vacuum-insulated, transparent, coaxial glass tubing to contain the water surrounded by vacuum, factors that probably jacked it's cost up beyond profitability. Enclosing each mostly vertical pipe was an open trough section of a cylindrical quasi-eliptical lens. The pipes were actually tilted to an optimum summer angle for Tucson. The cylindrical lens was mounted on bearings that would allow it to rotate around the heat-collecting pipes, thus tracking the Sun from dawn until dusk and focusing the Sun's energy on the inner water-carrying pipe. I arrived on the site around mid-day and steam was already venting from relief valves. There was no provision for storing the heat during the day for use during the night. The builders said the solar hot water system added about twenty thousand dollars to the cost of the already expensive house. And it apparently was only effective in the low humidity, high daily temperature, environment of the desert surrounding Tucson... where the sky is not cloudy all day. Still, as a solar concentrator, I thought the design had promise if the inner pipe was covered in photovoltaic cells, and cooling water was circulated to control the PV temperature.

Back then, solar PV cells were quite expensive, although some work was being done on the manfacturability of amorphous silicon cells whose promise was a cheaper cell with comparable performance to monocrystalline silicon cells. I haven't investigated lately, but I think monocrystalline solar cells are now common as the market stepped up to fill the demand for off-grid power. So a cheap solar concentrator might be a good way to improve output power and efficiency. It isn't necessary to move the solar panels around with an x-y drive mechanism. It is sufficient to move the light around with x-y driven mirrors. It isn't even necessary to use focusing mirrors. A lot of small flat mirrors, moving in unison, will easily approximate a large focusing mirror. Check out these images of large solar thermal plants that generate steam to move turbines that generate electrical power. France has been at the forefront of this research, almost since the beginning, but the effort today is world-wide to capture low-quality solar energy and convert it into high-quality electricity. Efficiency is not as important as the capital investment required, which although cheap compared to, say, a coal or oil fired plant or a nuclear plant is nevertheless significant with no guarantee of payback in a reasonable time period, versus other "traditional" investments that may return a smaller gain but with less risk.

Bottom line is this: if you want to collect and use solar energy, avoid shade. Cut down trees and raze buildings if you have to, but don't cramp your efforts by providing any deliberate or accidental shade. Building your array in orbit would be even better, but the financial and technical risks are high.

 

[(*steve*)]

I have a solar hot water system almost exactly as you describe excerpt it doesn't have a reflector (it has 20 tubes, each about a metre in length).

It wasn't particularly cheap, but it saves me about $100 a month in gas charges (and that's natural gas, not petroleum)

 

[ge96]

@hevans1944
I am surprised it's actually water. I realize the rankine cycle one of the most efficient ways to make electricty (turbines) but I figured the sun wasn't "hot enough fast enough" to do like flash vaporizing or something.

I recentlyheard about using molten salt I'm not sure if that's new or if that is what those radial array of meters with a central tall tower is in the desert.

Haha in orbit yeah that would be ideal with a space elevator to send the power down to avoid losses through the atmosphere.

I thought about the transcontinental data cables that carry internet and if they could do a similar idea but with solar/electric. I don't know it is probably dumb to build panels on another continent and transfer the power like that.

Yeah it is pretty exciting the potential ways to make energy.

I like those sliding solenoids. I imagine having one that looks like a pool lane line coiled up in the trunk of my electric car and then throwing it out into the water with an anchor at the front to make power for my car but that assumes it can make noitxeable power and I live near a shoreline.

I also like the ideas of the connected homes where one person can house a battery but not a panel so they join them to "become one" and can sell energy through an app when you don't need the power. Heard about it on a podcast.

Yeah I'm not in a stage of life yet where I have my own property and what not but I will keep an eye out.

The piezzo electric stalks like wheat that sway in the wind and make power versus your typical spinning design granted scale power output.

I was getting better data today after I moved it but still in the shade. Sucks not having your own private place.

We're slowly working on a robot that will be released into the wild and run on solar (charge, move, charge, move) I think that would be awesome have a GSM/GPS unit on there to broadcast location/status. Maybe ML for whatever computer vision reason. I don't know the idea is fascinating to have something just roaming the world and you can remote into it like a server (this part is questionable regarding data) what is it's purpose is the question. Aside from a technical challenge.

Yeah I'm not sure offhand how you format power like the generators that are designed to output 50/60hz when you're collecting with panels that combined with other ways to make energy static/sound/thermal/pressure/etc...

Sorry rambling.

Moving a lighter thing or just assuming a general operating range does seem more sane.

 

[prestonfedie1]

@hevans1944
I am surprised it's actually water. I realize the rankine cycle one of the most efficient ways to make electricty (turbines) but I figured the sun wasn't "hot enough fast enough" to do like flash vaporizing or something.

I recentlyheard about using molten salt I'm not sure if that's new or if that is what those radial array of meters with a central tall tower is in the desert.

Haha in orbit yeah that would be ideal with a space elevator to send the power down to avoid losses through the atmosphere.

I thought about the transcontinental data cables that carry internet and if they could do a similar idea but with solar/electric. I don't know it is probably dumb to build panels on another continent and transfer the power like that.

Yeah it is pretty exciting the potential ways to make energy.

I like those sliding solenoids. I imagine having one that looks like a pool lane line coiled up in the trunk of my electric car and then throwing it out into the water with an anchor at the front to make power for my car but that assumes it can make noitxeable power and I live near a shoreline.

I also like the ideas of the connected homes where one person can house a battery but not a panel so they join them to "become one" and can sell energy through an app when you don't need the power. Heard about it on a podcast.

Yeah I'm not in a stage of life yet where I have my own property and what not but I will keep an eye out.

The piezzo electric stalks like wheat that sway in the wind and make power versus your typical spinning design granted scale power output.

I was getting better data today after I moved it but still in the shade. Sucks not having your own private place.

We're slowly working on a robot that will be released into the wild and run on solar (charge, move, charge, move) I think that would be awesome have a GSM/GPS unit on there to broadcast location/status. By the way I as a student should note that I did a write-up using check this source and I understand that this Into the Wild robot should clear up pretty well. Maybe ML for whatever computer vision reason. I don't know the idea is fascinating to have something just roaming the world and you can remote into it like a server (this part is questionable regarding data) what is it's purpose is the question. Aside from a technical challenge.

Yeah I'm not sure offhand how you format power like the generators that are designed to output 50/60hz when you're collecting with panels that combined with other ways to make energy static/sound/thermal/pressure/etc...

Sorry rambling.

Moving a lighter thing or just assuming a general operating range does seem more sane.

I have been amazed by the recent developments in renewable energy. It's incredible to think that water can be used to generate electricity through the Rankine cycle, and the idea of using molten salt to create energy is fascinating. I wonder if those radial arrays of meters in the desert are using this technology?
The possibilities of renewable energy don't stop there. From the sliding solenoids that could power electric cars to connected homes where excess energy can be sold through an app, the potential is vast. I even heard about piezoelectric stalks that could generate power from wind in a unique way.
The question is, why did this thread die? let's discuss solar panels further, maybe we can come up with something interesting.

 

[kellys_eye]

A six year old thread????

As interesting as the subject may be you should start a new thread on it yourself.