Buying used panels from some random guy on Craigslist.

[Mannfamilywoodworks]

I’m looking at these sharp solar panels that the seller is saying put out 230w.
I’m going to get 8@$70 each
Total price with a cash discount is $500
I’ve never purchased used panels before.
What should I bring to check the panels? Clamp meter or a volt meter?
What should I visually check for?
Thank you all

 

[sunshine_eggo]

I’m looking at these sharp solar panels that the seller is saying put out 230w.

What is their rated power?

I’m going to get 8@$70 each
Total price with a cash discount is $500
I’ve never purchased used panels before.

Be prepared for disappointment.

What should I bring to check the panels? Clamp meter or a volt meter?

Yes. Yes.

On each panel, measure Voc and Isc. Look for outliers.

What should I visually check for?

Any damage of any kind.
Discoloring on the back face.
Age (date of manuf on the label?).
Can you find a datasheet for the panel model?

 

[chrisski]

If you bring a clamp meter, be sure to have a way to make and break the circuit. I use Anderson plugs for the quick disconnect. MC4s I can usually do by hand, but not always.

For the multimeter, they tend to be fused at 10 amps. Just make sure the panel is less than that.

I prefer the camp meter.

 

[wmgeorge]

If you bring a clamp meter, be sure to have a way to make and break the circuit. I use Anderson plugs for the quick disconnect. MC4s I can usually do by hand, but not always.

For the multimeter, they tend to be fused at 10 amps. Just make sure the panel is less than that.

I prefer the camp meter.

Your measuring voltage what does that have to do with the multimeter fusing or any fuses?

 

[GLC]

I’m looking at these sharp solar panels that the seller is saying put out 230w.
I’m going to get 8@$70 each
Total price with a cash discount is $500
I’ve never purchased used panels before.
What should I bring to check the panels? Clamp meter or a volt meter?
What should I visually check for?
Thank you all

All of my panels that I have on my setups have been used. Luckily I have been doing business with him for 3 years now with upgrades. He has them listed on FB and Craigs list. You never really know who is shady or not. Check the panels out yourself. So far I have never been burned.

 

[chrisski]

Your measuring voltage what does that have to do with the multimeter fusing or any fuses?

I thought you’d want to check amperage also

 

[Quattrohead]

Use a DC clamp meter, plug the connectors together whilst the panel is face down, then lift it up to the sun and make sure you have several amps flowing, somewhat close to the Isc of the panel.
Put it face down again to unplug. DC arcs are nasty.

 

[chrisski]

Use a DC clamp meter, plug the connectors together whilst the panel is face down, then lift it up to the sun and make sure you have several amps flowing, somewhat close to the Isc of the panel.
Put it face down again to unplug. DC arcs are nasty.

What a brilliant idea. I will probably forget that next time I use this.

 

[Mannfamilywoodworks]

What is their rated power?



Be prepared for disappointment.



Yes. Yes.

On each panel, measure Voc and Isc. Look for outliers.



Any damage of any kind.
Discoloring on the back face.
Age (date of manuf on the label?).
Can you find a datasheet for the panel model?

I appreciate everything you’ve said.
I’m going to ask him for more pictures now.
That Data sheet is specifically important.

Why would I be disappointed? Should I steer away from the used realm all together or is it worth the $500

 

[Mannfamilywoodworks]

If you bring a clamp meter, be sure to have a way to make and break the circuit. I use Anderson plugs for the quick disconnect. MC4s I can usually do by hand, but not always.

For the multimeter, they tend to be fused at 10 amps. Just make sure the panel is less than that.

I prefer the camp meter.

Multimeter is fused at 10amps!

This is valuable information as well. Thankyou.

 

[Mannfamilywoodworks]

Use a DC clamp meter, plug the connectors together whilst the panel is face down, then lift it up to the sun and make sure you have several amps flowing, somewhat close to the Isc of the panel.
Put it face down again to unplug. DC arcs are nasty.

Ill do this exactly. Hopefully the sun is shining.

 

[sunshine_eggo]

I appreciate everything you’ve said.
I’m going to ask him for more pictures now.
That Data sheet is specifically important.

Why would I be disappointed? Should I steer away from the used realm all together or is it worth the $500

Purchasing used anything from an unproven source has a high potential for disappointment.

 

[sunshine_eggo]

Ill do this exactly. Hopefully the sun is shining.

If it's not, reschedule the pick-up.

 

[Hedges]

Panels can deliver full Voc and Isc, yet have reduced Vmp and Imp. Other times, Voc or Isc will be sufficient to show a bad panel (3 out of 12 I tested).
I did some math and selected a couple oil-filled radiator heaters as test load, so got V load and I load, detecting the bad ones (2 more out of 12).

 

[Brett V]

Use a DC clamp meter, plug the connectors together whilst the panel is face down, then lift it up to the sun and make sure you have several amps flowing, somewhat close to the Isc of the panel.
Put it face down again to unplug. DC arcs are nasty.

Make sure you have a tool to disconnect the MC4 plug before doing this!

 

[wmgeorge]

Ill do this exactly. Hopefully the sun is shining.

Hmm what If the panels are fused?

 

[A.Justice]

I bought a bunch of 250w panels that were 15 years old for less than $50 each, and I'm not disappointed at all. They all put out at least 90% of their rated power. I'd buy used again any day.

Wouldn't OP need to bring something to load the panels to check the amperage?

 

[tinyt]

I am not sure if this is useful, accurate, and or worth it.
This one ships earlier but cost almost the same and only half the power rating.

 

[Mannfamilywoodworks]

Hey th

I am not sure if this is useful, accurate, and or worth it.
This one ships earlier but cost almost the same and only half the power rating.

ats actually pretty cool tool. Thankyou for that!

 

[Mannfamilywoodworks]

This is the data sheet from the panels I’m going to buy tomorrow.
Growatt specs are attached as well.
I’m buying 8 of these.
I’m assuming they’d get hooked up in series but I need to sit down and do some math first.

 

[Mannfamilywoodworks]

Specs

 

[sunshine_eggo]

Datasheet I found for that panel was from 2011.

ND-H230Q2 - Sharp Solar - PDF Catalogs | Technical Documentation | Brochure

pdf.directindustry.com

Pretty inefficient panel by today's standards. New panels are 30-50% more efficient.

Warranty:

Limited Warranty For Power: The warranty period with respect to power output1 continues for a total of 25 years from date of purchase by the first consumer purchaser, the first 10 years at 90% minimum rated power output and the balance of 15 years at 80% minimum rated power output. This warranty is transferable when product remains installed in original location at the time of product warranty registration.

https://es-media-prod.s3.amazonaws.com/media/u/bad/9e9/d9b/4a377fac554a5266604e7b20285d4e78/Sharp%20sol_dow_WRMOD_001.pdf

Assuming about 10 years old, they should produce 90% rated in STC conditions.

They publish a NOCT temp of 47.5°C and a Pmax coefficient of -.485%/°C

Based on age and "real world" conditions, if those panels meet spec, they'll produce about 185W.

 

[Mannfamilywoodworks]

Datasheet I found for that panel was from 2011.

ND-H230Q2 - Sharp Solar - PDF Catalogs | Technical Documentation | Brochure

pdf.directindustry.com

Pretty inefficient panel by today's standards. New panels are 30-50% more efficient.

Warranty:

Limited Warranty For Power: The warranty period with respect to power output1 continues for a total of 25 years from date of purchase by the first consumer purchaser, the first 10 years at 90% minimum rated power output and the balance of 15 years at 80% minimum rated power output. This warranty is transferable when product remains installed in original location at the time of product warranty registration.

https://es-media-prod.s3.amazonaws.com/media/u/bad/9e9/d9b/4a377fac554a5266604e7b20285d4e78/Sharp%20sol_dow_WRMOD_001.pdf

Assuming about 10 years old, they should produce 90% rated in STC conditions.

They publish a NOCT temp of 47.5°C and a Pmax coefficient of -.485%/°C

Based on age and "real world" conditions, if those panels meet spec, they'll produce about 185W.

Thankyou for taking the time to explain this.
185w kinda sucks lol I may just spend the money with santan solar on some of their used panels. They seem to be more reputable. Or maybe I’ll bite the bullet on new panels. I just don’t know where I can purchase 5-6 opposed to a pallet

 

[fromport]

Assuming about 10 years old, they should produce 90% rated in STC conditions.

They publish a NOCT temp of 47.5°C and a Pmax coefficient of -.485%/°C

Based on age and "real world" conditions, if those panels meet spec, they'll produce about 185W.

I am using 20 years old panels and in spring I get 94% of STC specs.
It might depend on brand/model but bang for the buck I could not be more happy with my used panels.

 

[sunshine_eggo]

Thankyou for taking the time to explain this.
185w kinda sucks lol I may just spend the money with santan solar on some of their used panels. They seem to be more reputable. Or maybe I’ll bite the bullet on new panels. I just don’t know where I can purchase 5-6 opposed to a pallet

185W is to establish expectations. There will be many times when you get more than this, but hot cells in warm weather with full sun will perform at that level. it's very common for panels in summer to perform to 70-80% of STC rated.

I am using 20 years old panels and in spring I get 94% of STC specs.
It might depend on brand/model but bang for the buck I could not be more happy with my used panels.

What about summer?

My 3 yr old Talesun 330W panels rarely perform to STC spec because STC spec rarely happens in the real world. I get closer to 90%. My panels are at 6500 ft, in the AZ high desert, so they actually get more than 1000W/m^2, and they experience more mild ambient temperatures than Phoenix, but 90's are pretty common.

My best performance is in the colder months where panel tilt is not as favorable, but the notable cold boosts Vmp. I've seen 110% in those conditions.