Which Panel should I get?

GoneSquatchin

Hello everyone,

I have an opportunity to buy individual GT panels from a local warehouse (usually only sells by the pallet). I have the option of either of the following panels:

• Topoint JTM250-96M
  • 250W
  • Vmp = 49.91V
  • Imp = 5.02A
  • Price = $200 Cash
• SolarWorld Sunmodule Plus SW 255 mono
  • 255W
  • Vmpp = 31.4V
  • Impp = 8.15A
  • Price = $250 Cash

Initially, I would be using one of these panels at my recreational off-grid cabin (12v 215ah GC battery bank) with an MPPT charge controller (probably the new Rogue)

Any opinions on these panels? Is one better than the other for my 12v charging?

Thanks,

Jeff

BB.

The Solar World would be better for charging your 12 volt battery (Vmp~2x Vbatt-charging voltage).

Another issue is the 50 Volts Vmp is a bit of an odd ball. It may be difficult to find "matching" panels later if you wish to enlarge your array.

Also, there is a weird range of ~55 to 72 volts where it is difficult to charge a 48 volt battery bank with these panels and "standard" MPPT type charge controllers. The voltage is too low to charge a 48 volt battery bank with 1 panel in series, and too high of voltage with two in series (especially in very cold climates).

If you plan on "growing" your array later--I would probably spring for the Solar World--They are a much more common panel size/set of ratings.

If the system is static (not going to change/grow over time), either panel would work, but the Solar World will be more efficient for the typical MPPT charge controller (some controllers will give you the efficiency for various Vmp-array vs Vbatt combinations). At best, maybe the MPPT will be 2-5 percentage points less efficient--Not a huge deal, but heat is the enemy of electronics--So running the charge MPPT charge controller cooler is also a good thing (less waste heat at the controller).

-Bill

GoneSquatchin

Great Feedback!

I was wondering about the goofy voltage of the Topoint. But, liked the price better vs. the Solarworld :-) But, as you say, I may regret saving that $50 in the future.

Thanks,

Jeff

SolarPowered

Solar Worlds manufacturing processes and performance far exceeds top point.

If you want other options Canadian Solar is lower in price than solar world, still a better product than top point.

Photowhit

Top Point went bankrupt back in 2014, assets bought by Jinko, not sure if they are honoring the TopPoint warrant.

Solar World brought us Tariffs, not sure I would want to support them....Doubt they can continue to compete with out subsidies...so who knows if they will be around long.

As Bill said the Solar World panels will be easier to find similar panels.

westbranch

to quote an old prof from a long time back, " buy quality, it will always be quality", and it never goes out of fashion. the definition is your call.

GoneSquatchin

Thanks for all the feedback regarding the panels!

The problem I'm running into is that this is the only local place to me that can/will sell me individual panels (and only because he has a few singles laying around). So I'm stuck with what he is offering. To order GT panels online was going to cost me as much (or more) as the panel for shipping... (Amazon and EBay only gets me good pricing and free shipping for 12v panels)

Anyway, thanks to all your input, I've ruled out the Topoint (It's a 96 cell panel).

westbranch

Hope we have you on the right track, in that you now know some of the limitations of some panels...

Photowhit

GoneSquatchin wrote: »

(Amazon and EBay only gets me good pricing and free shipping for 12v panels)
.

It's not a sin to string 12 volt panels! if you can get them at a reasonable price.

GoneSquatchin

Photowhit wrote: »

It's not a sin to string 12 volt panels! if you can get them at a reasonable price.

It's funny you say that... I think I'm going to take a step back with what I'm planning and not spend any money just yet. This is for my off-grid cabin (I have another thread about this). Last year was pretty successful (I think anyway) with just (1) 100W panel on a 215ah GC battery bank. I know I should have more panel watts to properly charge the batteries. Thus, the decision on the 250W panels. However, I also need something for cloudy/rainy weekends. So I think I'm going to buy an AC Charger first to run off the generator. I have to have the generator running a couple of times a day for other things anyway. Might as well have it charging the batteries at the same time. I'm figuring this will get my batteries the happy charge they want and give me time to mull over my panel/charge controller decision moving forward. Who knows prices might drop too.

For some reason though, I keep thinking I should keep this cheaper, simple (possibly more reliable), and better redundancy by using (2) 100W panels in parallel with a PWM CC. May also be less desirable to steal too... (As opposed to a single 250W 24v panel with MPPT CC)

Photowhit

Just a thought on the theft issue, I had built a shed to live in, while I was framing up an 'A' frame. I took a job 70 miles away and had a place to stay there so came and went Friday and Monday from the 'A' frame in 3 weeks people had figured out my schedule and robbed me blind. I told people if I wanted to hang a picture I had to go to town to buy a hammer and a nail. The odd things they left,.. solar panels and batteries, Propane bottle and regulator, though they took the propane heater hard plumbed mounted and operational....

Imurphy

You will most likely be better off with 2 100 watt 12 volt panels on a pwm controller. This will be cheaper and more efficient. You will spend a bit more on wire but in the long run it will be worth it.

What type of generator do you have? If you have a honda EU with the 12v output these work better then most 120 v chargers. You have a small bank, so you don't need a very big charger or generator. If you are concerned about them you can bring them home during the week to get a good float charge. then have the panels at the cabin keep them floated while you are there. But if you build it right, you should never have to start your generator to charge the battery.

GoneSquatchin wrote: »

It's funny you say that... I think I'm going to take a step back with what I'm planning and not spend any money just yet. This is for my off-grid cabin (I have another thread about this). Last year was pretty successful (I think anyway) with just (1) 100W panel on a 215ah GC battery bank. I know I should have more panel watts to properly charge the batteries. Thus, the decision on the 250W panels. However, I also need something for cloudy/rainy weekends. So I think I'm going to buy an AC Charger first to run off the generator. I have to have the generator running a couple of times a day for other things anyway. Might as well have it charging the batteries at the same time. I'm figuring this will get my batteries the happy charge they want and give me time to mull over my panel/charge controller decision moving forward. Who knows prices might drop too.

For some reason though, I keep thinking I should keep this cheaper, simple (possibly more reliable), and better redundancy by using (2) 100W panels in parallel with a PWM CC. May also be less desirable to steal too... (As opposed to a single 250W 24v panel with MPPT CC)

BB.

In general, the Honda 12 volt output on the eu2000i gensets is not very useful. Unregulated "12 volt" output for emergency charging (something like 8 amp)--And you have to set the ECO throttle off (as I recall)--Which uses a lot more fuel.

Running the Honda driving a good quality AC battery charger is usually more fuel efficient and much more available charging power (~96 watts from DC output, vs ~650 Watts from a 45 Amp charger @ 12 volts.

-Bill

GoneSquatchin

Well, now I'm up in the air again...

After telling the supplier that I wasn't going to buy right now, he dropped the price on the Solar World panels to $200 OTD. He claims they are $350 panels. Now I feel like I can't pass up that deal. I'm trying to get an answer from him if they are new and still in the packaging. If so, I'll probably just go ahead and buy it.

BB.

As long as you find a good MPPT controller that meets your needs (and you stay with 12 VDC battery bank, or get 2x panels in series for a 24 VDC bank)--You should be very happy.

-Bill

westbranch

just for price reference look at this list for Solar World, down near the bottom, may ease your stomach...http://sunelec.com/solar-panels

GoneSquatchin

westbranch wrote: »

just for price reference look at this list for Solar World, down near the bottom, may ease your stomach...http://sunelec.com/solar-panels

Yeah, thanks for the reference. The exact panel isn't listed there. But, it looks like it is a $300 panel. I may just take $300 and see how badly he wants to unload both of them :-)

westbranch

The second rule of Solar , or is it the first?, is.... loads grow with time! get 2 ...

Vic

GoneSquatchin wrote: »

Well, now I'm up in the air again...

After telling the supplier that I wasn't going to buy right now, he dropped the price on the Solar World panels to $200 OTD. He claims they are $350 panels. Now I feel like I can't pass up that deal. I'm trying to get an answer from him if they are new and still in the packaging. If so, I'll probably just go ahead and buy it.

Hi G S,

Have used various sizes of the SolarWorld Mono PVs in the power range that you are considering. They are top quality PVs, and they have been made in the USA for some years. All that i have installed are still working fine, and would have no concern about using them again.

You should ask the supplier if they are first quality, and not culled or returned due to some concern about them.

There is really NO packaging material, as they are essentially always palletized and shipped by Motor Freight.

The only other question you might ask the supplier, is if they frames are version 2.0 or 2.5. The 2.0 frames need to use Top-Down mounting, whereas the 2.5 (and 4.0 for that matter) frames can use top-down as well as bolting through the rear frame flange.

This difference may not be a big deal to you, but generally for smaller systems bolting form the rear is most convenient ... FWIW.

Agree with BB Bill, that the Topoint 96-cell PVs are an oddball voltage in the present scheme of things, and might be very hard to match later.

Have Fun, Vic

GoneSquatchin

Thanks Vic,

It's good to hear that they are quality panels.

I did confirm that the panels are new. As you expected, they are not packaged. He said they came off a pallet where the customer only wanted 18 or 19 panels and these were left over.

Any suggestions on what to look for as far as damage goes? Should I take a volt meter along and test the voltage output outside? (If it is cloudy/rainy, what reading should I expect?)

Thanks,

Jeff

Vic

Hi Jeff,

Would look for any dings on the frames, particularly near the top, where the glass enters the frame. And look for scratches on the glass.

You could use your meter to test the Voc, in the sun, but this would only show gross problems with them. Measuring the Imp is a bit more difficult, and there is a chance that, there could be an arc that might damage the MC4 connectors on the wires. Your meter would need to have a 10 A capability, which is usually a different jack on the meter. Also, the seller might not want someone doing an Isc measurement.

Am sure that you have asked what kind of warranty these PVs would have, and if he/she would give you an Invoice, if any Tax Credit is important to you, etc.

FWIW - Good Luck, Vic

GoneSquatchin

Hi everyone,

Just thought I'd follow up... (I'll follow up in my other thread too)

I ended up picking up (2) 255W Solar World Panels for $300. (He really didn't want to be stuck with 1 panel in his warehouse :-) Don't know if I'll use both at the cabin or not, but I figured the price was too good and I'll probably setup a small backup system at home too. So the extra panel won't go to waste :-)

Now to look for a mppt controller...

Thank you for all you assistance!

Jeff

Vic

Hi Jeff,

That is a great price! Thanks for the update, and have fun! Vic

semperfi123

Uni solar also went bankrupt $119 for a 24 volt 136 watt flexi panel , I have been looking into getting some of theses my self ,,any input ?

Thanks guys


http://www.mlsolar.com/unisolar-peel-stick-136-watt-flexible-solar-panels-home-solar-rv-boat/

Photowhit

Copied from a March post;

FWIW- I'm not a fan of the thin film Unisolar 136 Watt panels, It seems thin film may deteriorate faster than mono or poly type panels, add to that that I have yet to see a flexible panel that didn't yellow or have the surface deteriorate to diminish the output and.... well... I'm just not a fan. Unisolar went bankrupt back in 2012(reorganized?), don't think these are being made anymore. While I would buy a glass panel for cheap as they tend to be very dependable, I don't think I'd risk these. I think you can find glass panels as cheap or cheaper. Perhaps you have a steel roof that you want to run these down between the groove?

Let me add that if you have to have them one of the discounters have these for $99 + shipping but I've made it clear I'm NOT a fan of these! Note that they would also need to be used in a 24 volt system or with an MPPT type charge controller.

SolarPowered

Thin film is not the way to go. First solar is going through numerous class action lawsuits not meeting the depriciation or performance guidelines for financed commercial systems.
Thin film technology is no different than nano technology, we thought for years nano technology would improve conversion efficiencies in PV but it is still dead in the water.

We have learned through hybrid implementation of thin film coupled with poly or mono, conversion efficeincies would slightly increase marginally, however the elevated costs in manufacturing and production make it a moot discussion as if something anyone would really want to own. As an example a sanyo/panasonic HIT panel using hybrid techniques utilizing amorphous/monocrystalline. There was a bad batch of sanyo panels about 7 years back, it was an instance of fusing the amorphous to te mono, and the amorphous depriciated at double the rate of the mono. I changed out a few megawatts of the sanyo's under sanyo's warranty. You have to look out for thin films, and amorphous cells, these type of cells do not have a high resistance to temprature VS the rate of depriciation. Use alot of caution on those types of investments.

scrubjaysnest

Amorphous cells also don't hold up well to vibration as RV folks found out with the ones Harbor Freight was selling around 2010.