300 watt Solar Panel for $250 good deal?

[NoLimit]

I found a local deal on a ReneSola 300 watt 44.8 volt poly solar panel for $250 off CL. Is this a good deal? 
ReneSola Model # JC300M-24/Abh

I'm running a solarEpic mppt 40 amp solar controller in my van. 

I live out east where it can be cloudy often, should I get a mono panel as opposed to getting a poly panel? I contacted a local solar company and they say the poly is just as good as mono on cloudy days, any truth to that?

 

[jimindenver]

In my experience a poly is much better than a mono side by side on cloudy days.

It's not a big name panel but still under a buck a watt, so not bad.

 

[BradKW]

Quick google search shows that panel selling new for $270 and up, plus shipping. I'd say go for it...maybe if you wait around long enough you'll get a better deal and save what, $40?

http://www.eco-distributing.com/ReneSola-JC300M-24Ab-300-Watt-Poly-Solar-Module-_p_1252.html

 

[ZoNiE]

Good, not great, nearly the online cost as Brad stated. For me, Great pricing would be 50 cents a watt, and typically, you can get panels for about 60-65 cents a watt if you are not in a hurry and dog craigslist daily...

 

[NoLimit]

Good, not great, nearly the online cost as Brad stated. For me, Great pricing would be 50 cents a watt, and typically, you can get panels for about 60-65 cents a watt if you are not in a hurry and dog craigslist daily...

Out where I am, solar panels are not such a hot item so you don't see a lot of good deals on CL. Online, the prices are often a little bit cheaper BUT they will charge you about the same cost as the solar panel to ship it to you, $200-$300 shipping! Also, most online places have a minimum order of at least 2-3 panels, the ones that don't will charge a surcharge, but either way you still have to pay expensive shipping. If you can direct me to a better deal let me know....

 

[Hippiechk]

Home Depot currently has Grape Solar 100W poly panels on for $109.99 with free shipping. It's a bit more pricey & not sure if it's national but that is the price until the end of August in Washington State.

 

[NoLimit]

Home Depot currently has Grape Solar 100W poly panels on for $109.99 with free shipping. It's a bit more pricey & not sure if it's national but that is the price until the end of August in Washington State.

That's a pretty good deal, however, I want to avoid excessive wiring and connectors. I just want to get one big panel and put it on a rack, less hassle and when I want to tilt it I don't have a bunch of panels to tilt, just one.  Also, by putting one big panel in the center of the rack keeps the van looking more stealth, especially with the Prime Design ALU Rack I just ordered which has side bars on the rack.

 

[DannyB1954]

The problem with one big panel is if you're one panel fails, you lost 100%. With three panels, if one fails, bypass it and you only lost 30% of your capacity. With separate panels, you can wire them in series or parallel. A little bit more versatile. 100 Watt panels often come with free shipping. Large panels do not usually come with free shipping. Add that cost in. Does Craigslist seller give warranty?

3 panels can be mounted to a single rack so that all 3 are moved at the same time.

 

[NoLimit]

The problem with one big panel is if you're one panel fails, you lost 100%. With three panels, if one fails, bypass it and you only lost 30% of your capacity. With separate panels, you can wire them in series or parallel. A little bit more versatile.  100 Watt panels often come with free shipping.  Large panels do not usually come with free shipping. Add that cost in. Does Craigslist seller give warranty?

3 panels can be mounted to a single rack so that all 3 are moved at the same time.

Good points! However, I think I'm going to get the 300 watt panel for $250 and add a 100 watt panel with it for back-up. 
How can I mount 3 panels to a single rack to tilt all three at the same time? Link? Thanks.

 

[DannyB1954]

How can I mount 3 panels to a single rack to tilt all three at the same time? Link? Thanks.

Build a rack that holds 3 panels, and place them in the rack. Or the panels are usually made of aluminium angle iron. You could just fasten them all together using the mounting holes that come with them. Aluminium bar material is available in most places.

 

[NoLimit]

I bought the new Panasonic 325 watt HIT MONO panel that has the best efficiency rating at 19%, better than all other solar panels right now. They are tough to come but but a local solar installer is going to add an extra one to his order for me that will cost me $400. What good saving money on a panel when you are not going to get as much solar power that you can extract from a solar panel?
Here is the new panel:
http://cleantechnica.com/2015/10/09...ts-solarcitys-solar-module-efficiency-record/

 

[jimindenver]

96 cells, that thing is a beast. Still I'd love to get my hands on one to see what they are calling efficient now. I'll be interested in your peak numbers in sun and clouds, even speckled shade if you can manage it. Tech can change fast so there could be a game changer at any time.

 

[NoLimit]

96 cells, that thing is a beast. Still I'd love to get my hands on one to see what they are calling efficient now. I'll be interested in your peak numbers in sun and clouds, even speckled shade if you can manage it. Tech can change fast so there could be a game changer at any time.

I'll try to come back and do a review on the Panasonic solar panel once I get some experience with it. I'm going to even try to see if I can get some power out of a Wal Mart parking lot light at night like some RV'ers claim to do with their mono panels.

 

[jimindenver]

If you can do that, I'll be sold. My polys wake up at first light before the sun comes up but I wouldn't expect any thing usable at night.

 

[ZacLee]

In my experience a poly is much better than a mono side by side on cloudy days.

Perhaps you have this backwards?  Monocrystalline panels should produce more electricity than polycrystalline, especially under cloudy conditions...

 

[John61CT]

The differences are narrowing.

Watts per square feet of panels is more important.

 

[John61CT]

Panels may show some electrical activity in low light like that, but nothing produces any useful power.

 

[ZacLee]

Panels may show some electrical activity in low light like that, but nothing produces any useful power.

My panels produce 10-25% on cloudy days of what they produce on a clear sunny day.  My 2006 vintage kyocera poly panels produce a lower percentage on cloudy days then my 2016 vintage solarworld mono panels though.

 

[jimindenver]

I tested a Canadian solar 220w, a Schott poly 230w, two Bosch mono 245w, three Navajo 250w polys. In each case the monos dropped like a rock in mild clouds and my three Navajo 250w polys hold between 20-25a of the 40-50 amps peak in cloudy conditions. My test were run side by side with both voltmeters as well as identical charge controller set ups.

I did it because if you ask any one at the Colorado gathering, it gets cloudy here mid day all summer. I knew I needed power cloudy or not and went with what produced the most. YMMV

So think about it. Monos have a higher voltage and lower amps than a equal poly. In a PWM system those extra amps are shed along with the rest of the excess voltage and all you are left with is less amps. In MPPT you take the excess volts and create amps but I have to tell you that it takes a considerable amount of extra volts to make a big difference. Case in point I had the 220w on a test in sub freezing weather. It ran two volts above its norm but on a MPPT controller that two volts translated to 3/4 of a amp. So the slightly higher voltage of a mono isn't going to make up the difference in amps either.

As for the original concept of a smaller footprint. You have to go a ways back to see a noticeable difference in footprint. Anymore a 39x64 frame holds both monos and polys for a certain range, 39x77 the next step up. There was a half inch difference between the 245 monos and 250 polys but it was inside the frame. So effectively there is no difference in footprint. More efficient and advertised as such but it makes no difference to us in the real world.

Now it's been pointed out that tech has advanced since my panels were made three years ago. I can believe it since poly tech advanced very quickly to erase the footprint advantage. I would say I'd love to get my hands on some of the new panels that cost almost twice as much with a 1% increase in efficiency but honestly I'd go for more of the 435w poly on my truck rated at 20% efficiency. That thing is impressive in all conditions.

What I would like is someone to post the real time numbers of the systems showing charging by the moonlight. People with Unisolar panels use to claim getting a charge under a street light but in the end they showed voltage but no usable amps. My Schott poly use to show .45a at first light when everything was still colorless but nothing by the moonlight.

 

[John61CT]

> Panels may show some electrical activity in low light like that, but nothing produces any useful power.

"Like that" in this case meaning streetlights or moonlight.

Overcast skies are an entirely different matter, and would love to see objective data on differences wrt that.

The old Unisolar panels, those were like 18' long but the watts per area was woefully low even in peak conditions right?


Again, watts output per area is IMO the main metric to look for in mobile use cases.