Is anyone else impressed by this solar panel? - Page 1
Forum section: electronics / general

author: BrianHG
author_rank: Super Contributor
timestamp: January 04, 2025, 10:20:19 pm
content: Is anyone else impressed by this solar panel?Or, should I expect all other panels to operate as well, basically par for the course with partial shading and the compared solar panel in the video is just junk?

author: Whales
author_rank: Super Contributor
timestamp: January 04, 2025, 10:56:42 pm
content: How do they do this? Add diodes?

author: Analog Kid
author_rank: Super Contributor
timestamp: January 04, 2025, 10:57:31 pm
content: Curious to know: why would a panel's output go to zero if you shade a strip all the way across?Do the shaded cells form some kind of barrier to the current generated by the rest of the panel?

author: BrianHG
author_rank: Super Contributor
timestamp: January 04, 2025, 11:27:34 pm
content: Quote from: Whales on January 04, 2025, 10:56:42 pmThis is my guess.Probably smart active mosfet diodes to eliminate the 0.3v drop of a schottkey.You would probably need 1 for every 1-2 cells for granular cover.Either that, or the impossible each cell being 36v, low current and they all are tied in parallel.But, that leads to the question why don't the other solar panels already have diodes in them?

author: fourfathom
author_rank: Super Contributor
timestamp: January 04, 2025, 11:30:27 pm
content: Quote from: Analog Kid on January 04, 2025, 10:57:31 pmYes.The cell is essentially a current source (voltage-limited). When shaded this presents a very high impedance. This is why we use bypass diodes, usually across a bank of cells. Avoiding the Schottky diode drop voltage would be useful.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 05, 2025, 07:46:36 am
content: Quote from: BrianHG on January 04, 2025, 11:27:34 pmThey do, typically bypassing 3 segments. (For example, on a 60-series-cell panel, each bypassing 20 series string.)But why not more diodes, and why not active "ideal" diodes?Because it makes no sense to put amore expensivesolar panel in amore shadedplace. I might be captain obvious here, but solar power makes most sense in places where the sunlight is not blocked. Normal panels deal with intermittent, short-term partial shading "good enough", because the time of shading is just some % of total runtime, it doesn't matter. Now if you have a situation which has significant shading all the time so that it matters, you have lost anyway: with "normal" panels and "normal" inverters you lose a lot of production; with more expensive inverters (microinverters, optimizers) or specialized panels youstilllose a lot of production (compared to an ideal spot)andnow you paid more for the system, so there is no chance it ever pays for itself.Solution is: only install PV in decent places. There is no shortage of such places at all. Sure, noteveryoneowns good spots; so maybe your roof is not good for PV, but your neighbor's is.

author: Simmed
author_rank: Frequent Contributor
timestamp: January 05, 2025, 08:19:18 am
content: that familiar style of marketting and pictures on the websitewait a minutewhat is this ?https://diysolarforum.com/threads/renogy-1-m1-review-why-renogy-sucks.77914/some user videos shown online are not goodthey even said *expletives*very angry usersi dont know what is goin on here

author: Bud
author_rank: Super Contributor
timestamp: January 05, 2025, 08:28:12 am
content: Quote from: Simmed on January 05, 2025, 08:19:18 amJust a regular alien 3-handed sparky, nothing interesting.

author: brucehoult
author_rank: Super Contributor
timestamp: January 05, 2025, 09:52:17 am
content: That's not a hand.You should see how his party trick impresses the girls.

author: Analog Kid
author_rank: Super Contributor
timestamp: January 06, 2025, 12:25:23 am
content: Very strange photo editing: circled image is a copy of what he's got in his left hand:

author: Whales
author_rank: Super Contributor
timestamp: January 07, 2025, 10:28:47 pm
content: Whilst we're here, eBay and other online sites are full of solar panels with fake specs. Eg:There is no way this is a 300W solar panel.surface area = .78m * .77m = 0.6 m^2standard illumination = 1000W/m^2standard silicon solar panel efficiency = 20%power output = surface area * standard illum * efficiency = 120WFor this to make 300W you would need sunlight that's 2.5x brighter than standard (it does get higher than 1000W/m^2, but not by that amount!) or 50% efficient solar panels (I don't think even expensive germanium panels in research have gotten that high?).At least OP's linked solar panel doesn't claim impossible efficiencies. Whether or not they are as good as they say is another question.Also the claim of 80% output after 25 years is pretty bog standard (0.8%/year degradation rate), some panels claim better than that these days.

author: Analog Kid
author_rank: Super Contributor
timestamp: January 07, 2025, 10:37:52 pm
content: Seems even simpler than that: their "maximum power" figure isn't even correctly stated from their own specs:max. voltage (18.4) * max. current (7.44) = 136.9 wattsYou don't even get anywhere near that 300W if you take open-circuit voltage times short-circuit current, which of course is a nonsensical figure anyway.Whoever wrote up that spec couldn't even do basic arithmetic correctly.

author: BrianHG
author_rank: Super Contributor
timestamp: January 07, 2025, 11:15:49 pm
content: Quote from: Analog Kid on January 07, 2025, 10:37:52 pmPhony specked solar panels aside, you will not get the maximum power from your solar cell by shorting its output as its current will end up being lower than you would expect if it were another power source device like a battery.Hence the need for a MPPT power conversion circuitry to get the most power out of your solar cells.

author: nctnico
author_rank: Super Contributor
timestamp: January 08, 2025, 12:36:38 am
content: A panel like this could be interesting in places with a little bit of shading (like from a leaf or thin antenna, etc). But the cost has to be lower compared to adding an optimiser to a single panel. If you have shading over more panels, installing panels doesn't make much sense in the location. I'm also wondering whether the inverter used in the video has a good way to deal with partial shading; this could make a big difference in the actual effectiveness of having a panel with integrated countermeasures.

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 08, 2025, 01:33:27 am
content: Quote from: Analog Kid on January 06, 2025, 12:25:23 amLooks like AI-generated, or something.

author: BrianHG
author_rank: Super Contributor
timestamp: January 08, 2025, 01:38:57 am
content: Quote from: nctnico on January 08, 2025, 12:36:38 amI have room and permission to install 900watts worth on my apartment south facing balcony. Though, my problem is that a telephone pole and street wire over the middle of the day casts a moving shadow I cannot get rid of. Of course I am not able to return power to the grid or install them at the perfect angle, I just want to experiment and see what can be done with vertically mounted panels in situations similar to mine.

author: brucehoult
author_rank: Super Contributor
timestamp: January 08, 2025, 02:20:03 am
content: Quote from: BrianHG on January 08, 2025, 01:38:57 amPerhaps I'm weird that in 2025 I've never tried any solar panel.But I'm waiting for delivery any minute now of a kit from Temu (also my first experimental purchase there). I got email notification that it was delivered 2 hours ago, but maybe that was just when the NZ Post driver started their run, idk. That would be unusual, but maybe it's a different driver than usual over NY.https://share.temu.com/vq3m7b42dyAI don't know why the headline description says 140W when the other specs say 2x 40W panels. And a "100A" "controller" and various other connectors etc, all for NZ$78.51 (US$44) which seems pretty crazy.I don't really care if it doesn't meet the rated spec as I mostly just want it to trickle charge my motorcycle, which lives in a farm shed a distance from the house, with no electricity. It looks like it might come with a euro DIN / Hella cable which would be perfect.I live in a rented place and so can't put panels on the roof, connect something to the house wiring and mains supply etc. But I'm kind of interested in future in getting a stand-alone system that can at least power my computers and some low voltage LED lighting. Maybe the fridge, which is sticker on the door says 348 kWh per year, so 40W average. Maybe even my portable air conditioner, which uses 1100W when running (rated at 4 kW cooling/heating), which is running fairly continuously from 1 PM to 5 PM at this time of year, when it's very sunny (I'm at 35.5º S, so at solar noon (1:30 PM) at the solstice the sun is just 12º from overhead)That would leave only water heating and clothes and dishwashing as major loads. I already manage them by doing them in my electricity company's "free" 1 hour a day. Plus very intermittent and short time span electric kettle, toaster, microwave loads.Obviously that would need a bigger installation, probably with a battery. Stand-alone, not mains connected ... except maybe drawing from a 3 pin plug to top up, instead of having a battery, if that is possible. I want something that is NOT "installed" and that I can easily take somewhere else with me.My computers are a M1 Mac Mini that idles at 6W (max around 30W I think) and a Lenovo i9-13900HX laptop that idles at 15W but can draw up to 220W for short periods, or 160W for extended periods (5-10 min). But of course it has a battery more than sufficient to cover that. Plus a few Arm and RISC-V SBCs using typically 3W-5W. The biggest computer draw will be the Philips 329P 32" 4k monitor rated at 28W, but internet says 22W at minimum brightness ... I'm running it at 12%. I haven't actually measured it.

author: Someone
author_rank: Super Contributor
timestamp: January 08, 2025, 04:32:05 am
content: Quote from: brucehoult on January 08, 2025, 02:20:03 amThank for adding those other figures for context. Watch out on monitors as they often have the eco/low/legislative mode active for the headline power consumption figure where peak/realworld power is much higher. An example data sheet: 25W headline, 45W typical, 180W worst case.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 08, 2025, 05:58:39 am
content: Quote from: brucehoult on January 08, 2025, 02:20:03 amQuite a bit off topic, but I will never again buy anything from TEMU. I did buy one item. It was a thermal viewer, priced very attractively and I have actually been quite happy with the product. But TEMU is the most aggressive marketing entity I have ever encountered. My email inbox was swamped. Social media was swamped. Simple spam filters weren't adequate as they used multiple morphs of their business to go around them.The good price just wasn't worth the aggravation.

author: brucehoult
author_rank: Super Contributor
timestamp: January 08, 2025, 06:44:02 am
content: Quote from: Someone on January 08, 2025, 04:32:05 amAn unexpected power outage gave me nothing better to do than to put my Kill-A-Watt (clone) on the power strip that runs all the computers, and then test some combinations once it came back.So, yes, the 32" monitor is only 2W below its official rating in a real world config with lowish brightness.Incidentally, the i9 laptop also has an "eco" mode which limits it to 2.2 GHz and 75W, making the Linux build take 2m30s (55s longer) but using considerably less energy overall.Mac is 2020 original M1 Mini with 16 GB RAMi9 is Lenovo Legion Pro 5i (2023) with 24 core (5.4 GHz single core turbo) i9-13900HX with 32 GB RAM.Code:19W M1 Mac Mini in normal use, plus 8 pt gig ethernet switch, plus 7 port USB hub, plus VisionFive 2, plus Lichee Pi 3A45W plus 32" monitor53W plus 2nd 24" AOC monitor on SBC73W plus building Linux kernel -j8102W Mac idle, i9 laptop closed, charging (nearly full)67W laptop finished charging72W laptop open with display on233W laptop closed, building Linux kernel (first seconds)177W laptop building Linux kernel once CPU throttles (total time 1m35s)Splitting out individual items (not cumulative totals)...13W 2x SBCs plus ethernet and USB hubs (CBA plitting the out)6W M1 Mac Mini normal use+ 20W Mac additional load cross-building RISC-V Linux kernel (takes 4m35s)26W 32" 4k Philips 328P monitor at 12% brightness8W 24" AOC FHD monitor14W i9 16" laptop idle, lid closed+ 5W i9 laptop screen on+ 18W i9 laptop charging (nearly full)+110W i9 building Linux kernel in "adaptive" mode, once it throttles+ 56W i9 extra draw first 30s until it throttles84W all machines idle, 32" and 24" screens on, laptop closed (as it usually is)258W maximum load, bothMac and i9 compiling, laptop screen on, SBCs & 2nd monitor

author: Whales
author_rank: Super Contributor
timestamp: January 09, 2025, 08:08:35 am
content: Quote from: brucehoult on January 08, 2025, 02:20:03 amRough estimates based off the photo with dimensions:Width ~= 0.38mHeight ~= 0.25mSurface area ~= 0.095 m^2Power output under standard luminosity = 0.095 m^2 * 1000W/m^2 * 20% efficiency = 19WThese are 20W panels, a couple of them can give you something vaguely like 40W under full sunlight, assuming good MPPT.More than enough to keep your bike's battery aliveBut have a good look at the controller when it arrives, make sure that:(1) There is a fuse between batt and controller, so it doesn't catch fire if something goes wrong.(2) There is a fuse between panels and controller, ditto.(3) It doesn't pull current from the battery when the solar panels are dark.

author: brucehoult
author_rank: Super Contributor
timestamp: January 09, 2025, 08:54:55 am
content: Quote from: Whales on January 09, 2025, 08:08:35 amYup, already figured that out :-) 40 W total, not 40 W each.It arrived about 5 hours ago, at 5 PM.The panels have 2x USB connectors directly on the back of each panel. Just plugging a Milk-V Duo (about 0.5W) straight into it and pointing it at an overcast sky booted up Linux no problems. Plugging in my iPhone made it think it was charging but it didn't get anywhere. I'll try again in the morning when it's sunny.The controller looks exactly the same as everyone else's PWM controller e.g. the one hereHe says his is rated 30A, so I don't think I believe Temu's "100A". W/e. With 40W of panel you're only going to put 3A into the battery anyway, so you wouldn't want to take much more than that out via the load port either (at least not continuously). And this particular application (charging the motorcycle) there won't be a load anyway.QuoteI'm going to have to make up 3m-4m or so cables for both so, yeah, I'll put inline fuses. And a switch (or connector) in the cable to the panels, because those will need to be disconnected before unplugging from the bike.I might end up getting a smaller system for the bike charging later, something specifically designed for that, and repurpose at least this controller which seems well overkill for this task. OTOH, it's only $10 or so for the controller -- the panels are much more.QuotePretty sure it'll be ok in that regard -- at least not more energy that required to run the microcontroller and display. These seem to be a very common and popular controller.

author: nctnico
author_rank: Super Contributor
timestamp: January 09, 2025, 04:46:31 pm
content: Quote from: BrianHG on January 08, 2025, 01:38:57 amI'd start by finding an inverter which has good support for dealing with shadow. Dealing with shadow means sweeping over the voltage range to try and find the best point with most power. AFAIK most inverters are not doing this.However, if you can't dump power into the grid (and get paid for that) and can't use the power then it will be extremely hard to make it worthwhile to invest in solar at all. Unless you are paying over US$0,50 per kWh; then a battery may make sense financially.

author: tszaboo
author_rank: Super Contributor
timestamp: January 09, 2025, 04:57:08 pm
content: Quote from: BrianHG on January 08, 2025, 01:38:57 amIn Germany it's called Balkonkraftwerk. It's done regularly, and there are many pre-made kits for it. To the point where you can just walk into an Aldi shop, and buy a system together with your weekly groceries, and install it yourself, plug it into an outlet and done. No red tape.Maybe someone from there could help with how to select a system for that.

author: brucehoult
author_rank: Super Contributor
timestamp: January 11, 2025, 12:10:30 am
content: Quote from: Whales on January 09, 2025, 08:08:35 amI just tried my iPhone SE 2022 plugged directly in a USB port on the back of one (20W) panel, lying horizontally on my deck. From 12:00 to 13:00 it took the phone from 50% to 96%. The first 20 minutes took it to 68% (added 18%) and the other 40 minutes added 28%.Today's maximum solar elevation at my location is 77º at 13:30, so it's still just late morning now at 13:10 as I post this :-)Sorry to Brian "DDR" HG for kind of hijacking the thread! I see now there is a "Power/Renewable Energy/EV's" board, though this post isn't in it. I've only now started to think seriously about starting a small solar setup. Maybe I'll make a post over there.....