Question on which panel is a better choice for me.

[wired1]

Good Morning

I' haven't had luck getting answers on my own, hoping someone can chime in and help.

My choice is:

used 1 year 365 watt monocrystalline solar panels, 72 cells, VOC 47.6 volts , ISC 9.9A for $140. each, Pallet= 30 panels

OR

New 280W Poly-crystalline Solar Panel, Wattage: 280W, VOC 40.1Volts, ISC 10.1A for $106.50 each, Pallet = 27 panels


Either case I will buy a pallet and sell/save the rest as I won't need them all but shipping to me is insane so pallet makes much more sense.

My inverter is a EG4 3000 watt 48 Volt, it will take 500 Volts and 5,000 Watts Battery is 48V 200 AH. I may double that at some point in the future.

 

[HRTKD]

From an install standpoint, I would prefer the 365 watt panels. Fewer panels to install to get the same/similar watts.

500 volts / 47.6 volts = 10.5 panels, 3650 watts
500 volts / 40.1 volts = 12.4 panels, 3360

That's a difference of only two panels to stay under the Maximum PV Input Voltage of the solar charge controller. Note that the calc doesn't take into account the temperature coefficient. If you're in a climate that gets cold, you have to stay further under that 500 volts.

Either way, you're going to be selling a lot of panels unless you plan to put in two strings and be over-paneled.

I would look around for a local source so you can buy the exact number of panels you want and avoid shipping.

 

[wired1]

From an install standpoint, I would prefer the 365 watt panels. Fewer panels to install to get the same/similar watts.

500 volts / 47.6 volts = 10.5 panels, 3650 watts
500 volts / 40.1 volts = 12.4 panels, 3360

That's a difference of only two panels to stay under the Maximum PV Input Voltage of the solar charge controller. Note that the calc doesn't take into account the temperature coefficient. If you're in a climate that gets cold, you have to stay further under that 500 volts.

Either way, you're going to be selling a lot of panels unless you plan to put in two strings and be over-paneled.

I would look around for a local source so you can buy the exact number of panels you want and avoid shipping.

Thanks for your time today,

I can't avoid the shipping. I'm on a small Island in the Bahamas and everything comes by boat. 1 panel same cost as 30 for shipping.

I do plan on another 3K inverter down the road and I can easily sell any extras, but I think I would want them as spares as I have another building I could add another system to as well.

I guess my confusion is why are used mono more than new poly panels? Are they both good for my use and needs?

Do they both charge a 48V battery ok? Is the Mono better than the Poly enough to justify the added cost even thought hey're used?

 

[HRTKD]

I'm no expert on mono vs poly but I thought the mono panels are better.

Spares are good! I bought four panels in 2021 and the same model is no longer available.

As long as the PV array produces a voltage that is 5 volts higher than the system voltage it will begin charging. The way you wire the panels (parallel/series) allows you to bring the voltage up.

Panels in series, voltage adds up, amps stay the same.
Panels in parallel, voltage stays the same, amps add up.

 

[wired1]

OK Thanks,

Just so I understand this, if I wire 4 panels parallel, I'll have only 40.1 volts and 40.4 amps using the 280 watt panels? I can't see why one would do that, just want to understand better.

I still haven't been able to find out how much better Mono panels may be over Poly yet, to determine if used Mono panels are worth more than the new Poly panels?

 

[LydMekk]

You can have only 425V max for your MPPT so panel accordingly...
Usually 8 panels in series per string.
Check your manual for the max estimated amps per mppt input.

 

[wired1]

You can have only 425V max for your MPPT so panel accordingly...
Usually 8 panels in series per string.
Check your manual for the max estimated amps per mppt input.

Thanks, The EG4-3000 says 500 Volts. 5,000 watts maximum

 

[HRTKD]

Just so I understand this, if I wire 4 panels parallel, I'll have only 40.1 volts and 40.4 amps using the 280 watt panels? I can't see why one would do that, just want to understand better.

Panels get put in parallel when wiring them in series would exceed the Maximum Input Voltage of the solar charge controller. You can have a mix of series and parallel. For example, you might put four panels in series, another four panels in series and then take those two strings and parallel them.

There is a good write-up here on the forum about this. It can be found in the link below.

Solar panel strings: Parallel & Series explained

When solar panels are hooked up in series you connect the minus of one panel to the plus of the next panel. The voltages are summed, but the current remains the same: Putting panels in series is desirable as it keeps the amperage low, and amperage is the key factor in cost of the wire. Now...

diysolarforum.com

 

[Tomthumb62]

The EG4-3000 says 500 Volts.

You don’t want to put 495V into a 500V charge controller. It’s too close. If you go over 500V, you’ll fry the charge controller. Aka “let out the magic smoke”.

I’d go for 450V max. Because cold temperatures (below freezing) will cause the voltage to go up. Which ain’t likely to freeze in the Bahamas, but you do NOT want to get too close.

Make sure you add the voltage using the higher voltage number (open circuit Voc).

 

[Rocketman]

Both look good - from the little we know.

Here are a couple of thoughts…

New panels might be easier to resell.

If there a significant size difference? And will any size difference be better or worse for the physical layout.

One pallet will cost more than the other - does that have any effect.

Do you get warranties (from the manufacturer) with both?

Good Luck

 

[Tomthumb62]

I still haven't been able to find out how much better Mono panels may be over Poly yet

Supposedly mono produces same amount of power in smaller area.

Will Prowse did a compare video of different 100W panels and he was surprised to find that the poly panels produced slightly better.

 

[0truck0]

A 100 watt panel is 100 watts. Made from another material, a 100 watt panel is 100 watts.
The differences are when there is less-than-ideal conditions, doubting you have that as often where you live.
What strikes me is I think you say you have one 200ah battery....
You might can make a little side business installing the extra panels for other people given the expense of shipping panels to your island. New panels will be easier to resell.

 

[wired1]

A 100 watt panel is 100 watts. Made from another material, a 100 watt panel is 100 watts.
The differences are when there is less-than-ideal conditions, doubting you have that as often where you live.
What strikes me is I think you say you have one 200ah battery....
You might can make a little side business installing the extra panels for other people given the expense of shipping panels to your island. New panels will be easier to resell.

Otrucko,

I bought 4- 200 AH, 12 V batteries and wired in series to get 1- 200 AH, 48 Volt bank, I think about 10 kw?

I actually do want to help out as many people here as I can and show them Solar is way more affordable than all here thought it was....

We have power outages sometimes daily, almost always weekly, so they could really use it here. Ans plenty of storms wind through here as well.

 

[wired1]

Matter of fact, the Grid went down an hour ago here and through the saving grace of my batteries and inverter, I'm one of the few here that can still function.....Awesome!!

 

[0truck0]

My fridge went out and so my camper two-zone chest fridge became a two compartment freezer to save hundreds of dollars of frozen meats etc...
I have trailer set up solar, so in an emergency it can power some things in the house but Im not set up for running a full size fridge on top of other stuff, at least not for very long at all due to less battery power, but I agree, house solar is easy and affordable. I rent so do not have the motivation to install solar on the house...
Most people are not willing to be inconvenienced in the least, so will not consider the life changes to make solar work

 

[littleharbor2]

I guess my confusion is why are used mono more than new poly panels? Are they both good for my use and needs?

I'm going to say that the 280 watt panels are new, old stock. Nowadays 60 cell, or 120 perc 1/2 cell panels are in the 340 - 380 watt range.

 

[wired1]

I'm going to say that the 280 watt panels are new, old stock. Nowadays 60 cell, or 120 perc 1/2 cell panels are in the 340 - 380 watt range.

Thanks, been away and just saw this!

 

[740GLE]

How comfortable are you at moving these around? I’m guessing there’s a decent size difference between the two, those full size panels can be unwieldy.