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Hi everyone, I talked with SunPower tech support today, and they sent me the attached PDF that allowed me to decode the serial numbers on my used panels. (It turns out I bought 6 year old panels that were represented as 2 years old. I wish I had known how to check serial numbers before...

Thanks, everyone! To be clear, I would take my inverters offline to take this measurement, and I would do it in full sun. I bought a Lux meter, which is a very cheap and nifty device to have on hand for panel testing. It seems 120 kLux is about 1 sol or 1 kW/m^2. My plan is to establish the...

We're using the same panels. If it's of help, here's the complete datasheet on the SunPower 435 panels: https://us.sunpower.com/sites/default/files/sunpower-e-series-commercial-solar-panels-e20-435-com-datasheet-525546-revc.pdf As my inverter solution is different from yours, I'll let others...

Here are the preliminary tests on my panels. I consider these data a first order approximation, as testing conditions weren't ideal, panel temps weren't stable, panels weren't 100% clean, and I just guessed the temps on a half dozen panels after deciding that I should measure the temperature of...

Thanks! I would not have thought UV would penetrate the panel! Wow! I'm not surprised about the requirement for conduit, especially considering my panels will be >50V. However, I wonder whether Romex might also do. I suppose this can always be passed by the electrical inspector. Perhaps...

OK, I'll give it a shot then.... Specs on the inverter here: https://www.sol-ark.com/wp-content/uploads/2022/04/15K_Specs_4_27_22-1.pdf 500 V maximum MPPT range from 125 to 452 I don't know where you live, but where I live, I've calculated a maximum wintertime Voc of 95 V per panel (5F low)...

Depending on how flexible your design is, you could seasonally drop a panel or even a series within a panel (inside the junction box). That might be the cleanest approach. Perhaps you could use a tiny solar panel that would close a SPDT relay to tap your main string at a lower voltage point...

Thanks! Very helpful. In your estimation, will I be more accurate under stable full-sun and still-air conditions with an IR thermometer or with computation of the variance of Voc from nominal? I have no way of knowing which is more accurate. I notice with the IR thermometer, temp varies...

Thanks! Here's the schematic: ... and a picture of the box, obviously made mostly from stuff I had around: I found some cheap 2 ohm 100 W resistors on Amazon. Eight of them circle the box (16 ohm total). Those are in series with the 3 ohm 100W rheostat. I use an aligator clip to clip...

I'm a newbie, so take what I say with a grain of salt. However, it's my understanding that a common failure mode is the polymer back-sheet breaking down and allowing water intrusion. This happens around points that get particularly hot. You might be able to seal over the backsides of your...

I presume it's customary to post an introduction here. My name is Sarah. My partner and I live on waterfront on the American East Coast. I've been a long-time electronics and energy nerd, but I've been watching the solar world from the sidelines as solar prices have dropped and dropped -...

So I talked with SunPower tech support today. They stressed that my approach should be much more chemical than physical (e.g. abraisives / polishes). I can use a pressure washer up to 1500 psi. They had no recommendations as to whether mineral spirits or floor wax stripper would damage the...

Hi everyone, Newbie here! LOL My partner and I are in the beginning stages of installing a solar rooftop. We bought a pallet of 30 SunPower 435 panels that had been decommissioned from a solar farm. They were filthy when we got them. After cleaning them off with water, detergent, and a rag...

I guess it would help if I posted pictures! Haha... Here's the scummy film towards the bottom of the two pictured cells (but really everywhere on the panel to a lesser extent). I rubbed the area over the cell on the left with a paper towel: And here is the area I cleaned with mineral...

My partner and I were talking about hot solar panels last night. We were both impressed with just how blazing hot these things get! That started us to thinking about ventilation strategies. Our attic is already quite hot without ventilation. Our home has a hip roof with inadequate eve...

Hi everyone, I'm going to do a somewhat unconventional install on my microinverter array PV rooftop: I'm stringing lots of copper to carry to the DC of each panel into my garage, where my microinverters will be located. That way they last longer, and I can service/replace them more easily if...

I just bought a pallet of used SunPower (Maxeon) 435 panels, if that would work for you. They are out there, occasionally being decommissioned from solar farms. You can find various sources through SearchTempest. California and Arizona have a multitude of used panel sellers.