Sunpower Maxeon Solar Cell -  Discussion - Page 1
Forum section: electronics / general

author: Zucca
author_rank: Unknown
timestamp: September 22, 2014, 05:56:51 pm
content: Folks,I was thinking to start a home made solar panel project. I tipped in google "best solar cell" (I know I know, please have mercy on me) and I ended up here.To me it looks clever, but I don´t have any deep know how regardig a solar cell. I searched Maxeon in the EEVBlog but nothing was there, so here the post.Now, what is a Maxeon Solar Cell?They claim over 21% efficiency, with a lot of nice details and improvement, see attached details on the X-Series panels made with those cells, or herehttp://us.sunpower.com/why-sunpower/high-efficiency-solar-technology/there is also a nice video hereand here a nice white paper (very slow server, be patience):http://us.sunpowercorp.com/cs/Satellite?blobcol=urldata&blobheader=application%2Fpdf&blobheadername3=Content-Disposition&blobheadervalue3=attachment%3B+filename%3Dsunpower-module-degradation-rate%252C0.pdf&blobkey=id&blobtable=MungoBlobs&blobwhere=1300290935416&ssbinary=trueWhat I like is the fact of the +/- connections on the bottomand the reverse diode integrated in the cell itself, see video here:You can also buy those here:http://www.alibaba.com/trade/search?fsb=y&IndexArea=product_en&CatId=&SearchText=Maxeon++Solar+Cellhttp://www.aliexpress.com/store/product/Sunpower-Maxeon-Solar-Cell-21-8-Efficiency-3-34W-Semi-flexible-125x125mm-Mono-20pcs-lot-Solar/129132_1541941540.htmlor simply on ebay here:eBay auction: #251627066704eBay auction: #251648370523looks too cool to me, now what do you think?Thanks!

author: tom66
author_rank: Super Contributor
timestamp: September 22, 2014, 10:18:13 pm
content: I'd be very cautious buying solar cells off eBay. Who knows if they are the genuine article? So many fakes.Just my two pence.

author: Zucca
author_rank: Unknown
timestamp: September 22, 2014, 10:21:10 pm
content: You are right, like the eneloop battery

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 23, 2014, 04:03:36 am
content: For most applications, the figure that matters is $/W.

author: Zucca
author_rank: Unknown
timestamp: September 23, 2014, 12:24:24 pm
content: Quote from: mojo-chan on September 23, 2014, 09:29:55 amQuote from: NiHaoMike on September 23, 2014, 04:03:36 amThey claim a 25 year life cycle/warranty. This is relevant for both quotes above.

author: Zucca
author_rank: Unknown
timestamp: September 24, 2014, 10:34:58 am
content: No hope. I would have the beautiful classic DIY warranty (about 0 seconds), but I hope you know how to fix the crap you build.

author: Psi
author_rank: Super Contributor
timestamp: September 24, 2014, 10:58:57 am
content: Do you have info on what one of those panels weighs?I'm curious if i could add some to my big RC plane for extra flight time.Also, be careful with cutting edge stuff on aliexpress at a good price. It maybe genuine, but also a factory reject.

author: Zucca
author_rank: Unknown
timestamp: September 24, 2014, 11:05:47 am
content: Apparently this cell is the one they choose for a solar powered plane and boat, check this links:http://www.solarimpulse.com/timeline/view/6544#.VCKk3373aK0http://www.planetsolar.org/This could also be useful:Quote

author: Artlav
author_rank: Frequent Contributor
timestamp: September 25, 2014, 11:30:56 am
content: Well, i've ordered a dozen cells from Ebay linked here.They claim to be coming from Poland, but ship with USPS, and sound a bit chinglish-y.Hm...Will report back in a few weeks, i guess.

author: Zucca
author_rank: Unknown
timestamp: September 25, 2014, 05:06:57 pm
content: CoolArtlav, please if you can force an inverted voltage on the cell and see how the buid in diode is performing...

author: Psi
author_rank: Super Contributor
timestamp: September 26, 2014, 05:00:16 am
content: And please report back on the weight of a single cell

author: amyk
author_rank: Super Contributor
timestamp: September 26, 2014, 10:09:47 am
content: Quote from: mojo-chan on September 24, 2014, 07:10:37 amI'd be more inclined to wonder whether they'd be around in 25 years...

author: Artlav
author_rank: Frequent Contributor
timestamp: October 10, 2014, 04:28:55 pm
content: The cells have arrived.Beautiful blue-weird colour.Back side:They were fine overall, but there is some discolourations near the edges:Not sure if it's ok or not.The cells are paper-thin, flexible and feel very fragile.The front surface is changing colours of blue in a rather peculiar fashion.Don't ever touch the front surface - it absorbs fingerprints and contaminants with no hope of removal.My father, who made solar cells in the 90s, said that the surface is likely a dense pack of tiny pyramids, giving the colour changes and responsible for the dirt absorption.Each cell weights exactly 7g, on +-0.05g scale.It's night out (and winter is approaching), so not sure what performance they would get in the sun - i'll test on the nearest sunny day.Being put 10cm away from a 150W metal halide arc lamp it gives 0.65V open circuit and 3.5A short circuit.A luxmeter gives 80000lux at this distance, which is close enough, but the spectrum is likely wrong.The cell heats uniformly when in front of the lamp, getting warm almost instantly.One thing is certain - these won't survive any time exposed to the elements, so i'll better find something to encase them into.Any ideas?What else to test?Zucca asked about reverse voltage test, but i'm not sure what exactly to look for.

author: Zucca
author_rank: Unknown
timestamp: October 10, 2014, 04:51:35 pm
content: NICE! Thanks brother O0! It looks like it will be a little bit hardcore for a DIY solar panel, they look very delicate devices; but I like the challenge.Quote from: Artlav on October 10, 2014, 04:28:55 pmThis is the theory on normal Solar Cell/panel:http://pveducation.org/pvcdrom/modules/bypass-diodesJust imagine for this one there is a reverse diode implemented in the cell itself. Like This:Negative SC Terminal ---|>|--- Positive SC TerminalJust take a lab power supply unit , set the voltage to (my best guess) 5V and turn the current to 0A. Connect the + of the PSU to the - of the SC, and the - of the PSU to the + of the SC.SC must be in dark condition, no light on it. Now increase the current on the PSU and see how the SC voltage reacts. I would like to know what is the forward voltage (best case the I/V plot) of that diode and how the cell is handling the thermal dissipation. If needed increase the 5V.Don´t destroy the cell for me though... keep one eye on the temperature. It would be very interesting but I do it only if you can/have time!

author: solarcross
author_rank: Newbie
timestamp: October 11, 2014, 01:34:25 am
content: I've used the same cells for a couple projects...I bought a whole stack of 150 cells for just over $500 about 1.5 years ago..

author: Zucca
author_rank: Unknown
timestamp: October 11, 2014, 02:00:51 am
content: Funky bike! Are you happy with those solar cells? Any tips for the DIYer out there?

author: solarcross
author_rank: Newbie
timestamp: October 11, 2014, 10:56:05 pm
content: cells are pretty good, cant wait for +28% efficiency PV cells to hit the market..good rule of thumb.. build your PV array at double the watts of the output you need

author: Artlav
author_rank: Frequent Contributor
timestamp: October 14, 2014, 04:54:29 pm
content: In the end, i decided against trying to connect and laminate them myself.The things are too damn fragile.Fortunately, my father still had contacts in the industry, so i found a place that laminated them professionally for me.They also measured the performance of the completed panel under the standard conditions:For the 10 cells in series:Each cell is 0,01522 m^2 (including lack of corners), so total area is 0.152 m^2.Isc=6.35AUoc=7VIm=6.04AUm=5.4VTotal power: 33WThat comes out to about 21.6% efficiency.2% losses in the lamination, so the cells themselves give out about 22.1%Seems legit.The voltage range is good for a single cell li-po battery charging, or USB charging.No testing yet on the diode performance - i'd like to see how the panel as a whole performs under partial shading conditions, rather than doing shenanigans with a power supply.

author: Zucca
author_rank: Unknown
timestamp: October 14, 2014, 05:25:34 pm
content: COOL! Nice Job!The efficiency>20% is a very good news. Do you know the SC temperature (at least the ambient temperature) when it was spitting out the 33W?Regarding the connections I was thinging to build me a spot welder, like this onehttp://www.avdweb.nl/tech-tips/spot-welder.htmlbut it seems to me that you can just solder a tab wire on it, but with my poor hands it could end up in a dirty job....Quote from: Artlav on October 14, 2014, 04:54:29 pmReasonable. Since you have already a solar panel, you could cover just one cell (a piece of paper or plastic?) when the sun is shining and look on what happen to the voltage across that covered cell... or if you don´t have the access on the single cell terminals just report the variation in voltage/current with or without one cell covered.By choosing another cell to cover you could test is the variations are pretty much the same (so diodes are equals in the cells, as expected).

author: Artlav
author_rank: Frequent Contributor
timestamp: October 14, 2014, 05:50:17 pm
content: Quote from: zucca on October 14, 2014, 05:25:34 pm979 W/m^2, 27 *C ambient, as measured in the chamber.Quote from: zucca on October 14, 2014, 05:25:34 pmBad idea.These are silicon, that won't weld itself.And, they are only 0.2mm thick - any pressure enough for a good spot welder current would punch through them or crack them. And, perhaps, burn through them.In the panel they are just soldered together, with a special flux i presume.

author: Zucca
author_rank: Unknown
timestamp: October 14, 2014, 06:01:52 pm
content: Quote from: Artlav on October 14, 2014, 05:50:17 pmI overlooked that in the report. Sorry... BTW I would love to know your language.Quote from: Artlav on October 14, 2014, 05:50:17 pmGot it, you are right. Interesting, which means that the "solid copper base"http://us.sunpower.com/why-sunpower/high-efficiency-solar-technology/it at the end a paper thin layer.... of silicon? WOW

author: madmalkav
author_rank: Newbie
timestamp: March 24, 2015, 06:47:09 pm
content: Hi everyone. First of all, sorry for the thread necromancy, but I'm quite lost.I'm a computer technician and recently I got unemployed. I have been considering to buy some of this Sunpower cells to play a little but I'm quite lost in some aspects.First aspect: how to laminate the cells. Something like this will be ok?http://www.instructables.com/id/Make-rad-solar-panels-with-a-sweet-desktop-laminat/?ALLSTEPSSecond aspect: how to solder the cells. OP says they are somewhat delicate, so I don't know what will be the proper method to connect them.Third aspect: electronics. Will connecting the output of the cells to a regulator like this be correct?http://eud.dx.com/product/mini-dc-dc-voltage-stabilizer-regulator-module-red-844126106#.VRGGKOEYHlYThanks and sorry if all this is already explained elsewhere, I swear I couldn't find it.

author: Psi
author_rank: Super Contributor
timestamp: March 24, 2015, 07:12:29 pm
content: I'm working on a quadcopter which can fly on solar power alone (will still have battery) and I'm using these panels too (after reading this thread a while back)As you say, The real issue with them is protection from cracking. You basically have a paper thin silicon wafer. I'm working on a carbon fiber reinforced epp sheet and transparent film covering. Most important for me is keeping weight down.madmalkav, yeah they are bendable but any impact force cracks them.You can solder wire to them as long as you do it on a flat surface and dont press the iron down much. (Best to let the solder ball up and bridge the iron to the tab)

author: madmalkav
author_rank: Newbie
timestamp: March 25, 2015, 08:59:36 am
content: Please keep us informed on your progress. I think I will try that way of laminating just to see if it works, but I won't order anything until I can find a DC booster that can take three of this cells and boost it to 5V 2A.

author: Zucca
author_rank: Unknown
timestamp: March 25, 2015, 11:24:05 am
content: +1I would love to see a EEVBlog procedure to build a DIY Solar Panel....

author: madmalkav
author_rank: Newbie
timestamp: May 10, 2015, 04:38:11 pm
content: Hi again. I have retaken the project after some months busy with other stuff. I have been looking for DC-DC boost circuits and seems they start to be efficient enough from 3V, so I will go from using 3 cells to 6 or perhaps 9, but I can use some help on deciding wich IC shall I look for: most I have seen are rated for maximum 3A input and I'm afraid I'm not understanding the information properly.Also, as my plan is to get a 5V 2A USB outpu, shall I use a TPS2513 after the DC-DC booster?Thanks for reading.

author: Red Squirrel
author_rank: Super Contributor
timestamp: May 10, 2015, 08:17:58 pm
content: Cool stuff!I recently been considering building a small solar system for my house, even though we don't get much sun, I figured it would be a fun project and for when we do get sun it would still help. Long term project though, don't quite have the money yet. I'd want to do like 5kw, but don't think I really have the room on my roof as there's only really one area that would be good, so in all reality I'd probably do like 1-2kw.Canadian Tire has solar panels on sale so I bought a small crystaline 30w one to play with, and it's actually amazing the power you can get even with a small one. I was not expecting it to be able to spin a brushed DC motor directly, but it easily can. I've been testing various loads on a small battery bank to discharge and recharge the batteries to get a feel for just how much time it takes to charge and so on. I'll build a portable power pack with cig lighter plugs, lights, small inverter etc for camping or emergency use, mostly just for a fun little project. If ever I build a shed I might even just make it solar, for the lights and such.

author: Stormwind
author_rank: Newbie
timestamp: November 07, 2016, 04:55:21 am
content: @solarcross and @Artlav - if you are willing, it would be great if you could share some details of your panel construction (like material used).I'm working on similar panels for lightweight backpacking.Thanks!

author: vishalniit
author_rank: Newbie
timestamp: November 29, 2016, 05:16:26 am
content: Hi,What is the genuine place to buy this solar panel, i see lot of provider providing this on eBay and Alibaba how to figure out which one is genuine. Also is there any better product than this, as i see some chinese cells claim 30% EEF, which i doubt.In this thread somebody mentioned about building a RC copter using solar cell, what happened to that idea.RegardsVishal Gupta