Used Trina Panels?!

[charles_m]

So I found a guy on the local CL selling 1200 watts of Trina solar panels (4 x 300w). They have actually never been installed but are a couple years old.

Solar Panels and Charge Controllers. 235w, 250w, 300w

and

1200w of solar panels. Trina 300w. big panels.

Id be saving about $600 to buy from him as opposed to online (the freight would be $370 of that)

What do you guys think?

I know I'd lose the warranty...but I'd be saving about 62% on the cost of my panels...

[crazycal]

Are they 12 volt?

[claydbal]

looks like old skool mono stuff. nothing matches. charge controllers are pwm. this is antiquated , used, no guarantee, mismatched equipment. and, looking at specs, will be 24v system and too much for the charge controllers.

looky
Premium Kit

[superdave]

SolarPeace 195 Watt 24V Monocrystalline Solar Panel
and you get a warranty

[charles_m]

Im more interested in the panels in the second ad--a matching set of 4, 300w Trina panels.

They have never been installed and are 36V panels.
I will be using a Morningstar Tristar 60A MPPT charge controller into a 24V battery bank, so I'm not worried about any of that stuff.
From what I've read, the efficiency of mono vs poly seems almost negligible.
What I'm trying to figure out is if these Trina panels are quality enough and if the lack of warranty is worth the 60% savings in upfront cost (1600 vs 900).

The panels I was originally considering are these:

SolarWorld SW 315 Pro XL

15W more and they are Mono, which, I'm not sure how much I am worried about.

I am set on 4 panels, and their dimensions cannot exceed 40"x80"

I want 1200W of rated panel power.

[superdave]

a little cheaper,SolarWorld 315 Watt Solar Panel, Sunmodule SW315 Mono dont know about shipping cost. good people here.

[charles_m]

Thanks for the input, everyone!
I decided to go for it. Shipping charges on all the panels I could find on the net were about $360-380.
He also had racking, and a brand new charge controller for a great deal, so I'm saving a ton of money, and not paying shipping or taxes--close to $700 between the panels, racking, controller, and cables.
He's a professional installer so I feel good about the deal and he's been nothing but professional and honest on the phone. Good vibes, ya know?
Picking them up tomorrow and I'll let you know how things pan out!

[claydbal]

charles, i wasnt dissing on the mono, i bought some myself. i ws just alerting you in case you hadnt done your study. and the price would reflect lower for mono. good stuff has been said about trina. hoping they are what is advetised and work wll for you.

right now, i have 4 100w panels and 480 ah battery bank with 40a mppt. it WAS almost balanced for my appliances but i added a dorm sized fridge which put it over the top and now i have to supplement charge about every third day. it would be balanced if i move the bus from under the afternoon shading, but im trying to experiment in real world conditions. its obvious i need at least 2 more panels and 2 more batteries.

interested in how you will mount the panels, as i am going to redo the fubar mounts i originally built of wood.

[Redbear]

Please note: MPPT controllers take a higher voltage at less current, and convert it to lower voltage at higher current. That's why they squeeze more watts out of a panel, rather than loading the panels down to the actual battery voltage. Even at maximum amps out, less volts equal less watts.

You can use a set of 36 volt panels on a 12-volt battery bank with the right MPPT controller. Check the MPPT model's specs. I may be wrong, but I expect the higher panel voltage would also begin to charge batteries earlier in the day and continue charging later into the afternoon than lower voltage panels.

But in the specs I've read (Outback), the MPPT controller efficiency goes down somewhat as the voltage differential increases. This means you would get slightly more wattage charging a 12-volt bank from 36 volts rather than series-wiring the panels for 72 volts, assuming you can eliminate the losses in the wiring for twice the amps into the controller at the lower voltage.

I maintain two 24-volt systems that are almost 30 years old. Each has at least 18 pairs of 12-volt panels in series, with the pairs wired in parallel direct to the batteries through over-voltage disconnects. The systems are very inefficient when recharging the batteries after they are deep-cycled. I expect to convert them this year to MPPT systems with the panels series-wired for somewhere around 60 to 100 volts. The limit is the maximum input voltage rating of the controller. In my case the calculation must stay below the sum of the open circuit voltages of the series-wired panels, plus the adjustment factor for the increase in the output voltage of the panels in cold weather down to about -25°F.

[superdave]

you are correct redbear. i use the outback mx60 charge controller. it's worked flawless for ten years now. i first had 3 mismatched panels 36 v 30 v and 12 v hooked up at 78v. recently i bought 3 275 watt 30v panels and wired them at 30v for my 12v system. when i go to 24v i can add 3 more panels, 1600 watts max and raise my voltage to 60v, i would need 30.9v for absorb 31.2 to equalize . last year i installed a system on a friends rv, he used the morningstar mppt charge controller and loves it.

[jazty]

Originally Posted by Redbear

This means you would get slightly more wattage charging a 12-volt bank from 36 volts rather than series-wiring the panels for 72 volts, assuming you can eliminate the losses in the wiring for twice the amps into the controller at the lower voltage.

Yes indeed. Here is a nice tool for cable sizing: DC Cable Sizing Tool - Wire Size Calculator - MM2 & AWG - solar-wind.co.uk. I have used it for all major DC wire runs inside my bus. There are more accurate ones out there, but they are also more confusing. Go for 1% acceptable loss and you'll be golden.