Is price always the first consideration in solar panels?

[OffGridInTheCity]

One thing about poly vs mono is that poly is significantly larger/heavier than mono - maybe 20%. So if you have a space problem, it might be worth more $ for mono. Also, ploys are blueish and monos are blackish - and this might also affect a decision if you have wiggle room on the budget.

The size difference means that if you go one way on an array you it pushes you to expand with the same type within the same array due to physical dimensions.

Here you can see me grafting on 2 x mono + 4 x poly(s) to make additional 3s strings on a mono array. All panels are same wattage = 285w. Doesn't look nice and mounting was a challenge due to different sizes and thickness but this end of the array is in the back corner of the property and not very visible so I 'held my nose' and went with it.

I bought 40 x used polys from @SanTan Solar (ebay) at $70 each for my 'emergency stash' and didn't realize how different poly is from mono when purchasing. Up to that point all my panels were mono at $200 panel so I was blinded by $70. Poly is typically cheaper because it's larger/heavier and now I understand .

 

[B-Mod]

Used panels, no tax credit, new panels 30% tax credit

 

[Chester Gal]

One thing about poly vs mono is that poly is significantly larger/heavier than mono - maybe 20%. So if you have a space problem, it might be worth more $ for mono. Also, ploys are blueish and monos are blackish - and this might also affect a decision if you have wiggle room on the budget.

The size difference means that if you go one way on an array you it pushes you to expand with the same type within the same array due to physical dimensions.

Here you can see me grafting on 2 x mono + 4 x poly(s) to make additional 3s strings on a mono array. All panels are same wattage = 285w. Doesn't look nice and mounting was a challenge due to different sizes and thickness but this end of the array is in the back corner of the property and not very visible so I 'held my nose' and went with it.
View attachment 172808

Very nice system you have there! Thanks for the heads up about the weight and size. At this point in my neebie solar position, I am more worried about the performance differences. But thanks for the warning. I'll keep this in mind when making future purchases.

 

[sunshine_eggo]

One thing about poly vs mono is that poly is significantly larger/heavier than mono - maybe 20%. So if you have a space problem, it might be worth more $ for mono. Also, ploys are blueish and monos are blackish - and this might also affect a decision if you have wiggle room on the budget.

The size difference means that if you go one way on an array you it pushes you to expand with the same type within the same array due to physical dimensions.

Here you can see me grafting on 2 x mono + 4 x poly(s) to make additional 3s strings on a mono array. All panels are same wattage = 285w. Doesn't look nice and mounting was a challenge due to different sizes and thickness but this end of the array is in the back corner of the property and not very visible so I 'held my nose' and went with it.
View attachment 172808
I bought 40 x used polys from @SanTan Solar (ebay) at $70 each for my 'emergency stash' and didn't realize how different poly is from mono when purchasing. Up to that point all my panels were mono at $200 panel so I was blinded by $70. Poly is typically cheaper because it's larger/heavier and now I understand .

Ummmm... Propane much?

 

[zanydroid]

You really are PVGIRL!!!!! I'm writing this down right now to check against the panels I'm going to buy. Thanks for the speedy answer!

The inverters and batteries are usually the bottleneck for grid tie and permitting. Most of the time if you buy standard size range panels it is fine. People get into trouble when they use panels that are intended for EG mobile. Though that is double bad because you also have a lot more racking, balance of system, when the panels are that small.

Hot take: if your panels look normal size range the only time the POCO or AHJ will have a chance to say anything is when they review the plans and interconnection agreement. And the POCO mostly cares because your panel output combined with inverter output determines how much export can happen.

As in, if the inspector comes and sees a million 100W panels up there… questions will be asked

 

[Balrog006]

Used panels, no tax credit, new panels 30% tax credit

Only if they audit your cost breakdown and find the documents showing they were used…?

I kid, no one should ever fudge anything to do with their taxes, the IRS has to eat too.

 

[Chester Gal]

Used panels, no tax credit, new panels 30% tax credit

Ah! I totally forgot to factor that into the equation. That makes a huge difference in the eventual price per panel of the new ones. So that brings down their cost to $122.50 and that's $.32 per watt. I think that just changed my mind about which to buy. Thank you!!!!!!

 

[zanydroid]

60 and 72 cell panels are actually a single string. PV cells put out somewhere over .5 volts. 72 cells in series yield something over 36 Vmp. 60 yield something over 30 volts. 120 and 144 perc 1/2 cut cells are basically two panels in one They should be mounted in portrait orientation. this will have the upper 1/2 of the panel out of the shadows when they creep up from the bottom of the panel.

Yup. To follow up on my rant.

If the standard cut modules are arranged with each section in portrait. Then hard shading at the bottom edge will basically close to zero the output of the string. Doesn’t matter what kind of optimizers or bypass diodes you have. Still Zero. Need a design with a ton of bypass diodes like CIGS to get anything.

With half cut you get 50% until that shadow creeps above the midpoint.

As a corollary for single cut you would likely want the sections arranged parallelish to the most common shading. For half cut you have two usable orientations at 90 degrees due to the geometry. One will leverage bypass diodes the other would leverage the parallel wiring

All that said, there’s a limit to how much you can optimize this. The real answer is to not have shading.

 

[Chester Gal]

Only if they audit your cost breakdown and find the documents showing they were used…?

I kid, no one should ever fudge anything to do with their taxes, the IRS has to eat too.

The problem is that after they eat, there is nothing left for me but bread and water.

 

[Chester Gal]

Yup. To follow up on my rant.

If the standard cut modules are arranged with each section in portrait. Then hard shading at the bottom edge will basically close to zero the output of the string. Doesn’t matter what kind of optimizers or bypass diodes you have. Still Zero. Need a design with a ton of bypass diodes like CIGS to get anything.

With half cut you get 50% until that shadow creeps above the midpoint.

As a corollary for single cut you would likely want the sections arranged parallelish to the most common shading. For half cut you have two usable orientations at 90 degrees due to the geometry. One will leverage bypass diodes the other would leverage the parallel wiring

All that said, there’s a limit to how much you can optimize this. The real answer is to not have shading.

Very timely post because I just received a reminder about the solar tax credit available for the new half cut panels. This would bring their final price down to $.32 per watt after the rebate. I'm now seriously considering these. Thanks for the post!

 

[OffGridInTheCity]

Ummmm... Propane much?

10 x 100lb bottles = 200gal. They are easy to handle/fill, no permit needed. Part of the severe emergency plan (think Puerto Rico) during winter when PV is not enough

 

[Chester Gal]

The inverters and batteries are usually the bottleneck for grid tie and permitting. Most of the time if you buy standard size range panels it is fine. People get into trouble when they use panels that are intended for EG mobile. Though that is double bad because you also have a lot more racking, balance of system, when the panels are that small.

Hot take: if your panels look normal size range the only time the POCO or AHJ will have a chance to say anything is when they review the plans and interconnection agreement. And the POCO mostly cares because your panel output combined with inverter output determines how much export can happen.

As in, if the inspector comes and sees a million 100W panels up there… questions will be asked

Luckily these are normal sized panels. I'm going to call my utility company and find out exactly what is involved and how to go about it.

 

[sunshine_eggo]

10 x 100lb bottles = 200gal. They are easy to handle/fill, no permit needed. Part of the severe emergency plan (think Puerto Rico) during winter when PV is not enough

I'm leasing a 100gal unit for one of the trailers... $100/year. We've used it so little, I first filled it in April of 2022... still have 60 gallons... Absorption fridge at night was the biggest drain

 

[Solarcabin Channel]

10 x 100lb bottles = 200gal. They are easy to handle/fill, no permit needed. Part of the severe emergency plan (think Puerto Rico) during winter when PV is not enough

How much is propane in your area?

 

[Solarcabin Channel]

Price is always my first consideration whether it be solar equipment, cars or women.

Never be afraid to haggle over price!

 

[littleharbor2]

One thing about poly vs mono is that poly is significantly larger/heavier than mono - maybe 20%.
.

I have to disagree with your statement here. I believe what you have is older 72 cell poly panels and newer 60 cell panels. Panel efficiency has really improved over the last 10 years. When I was in the business I sold, probably every brand panels made at the time. One brand I sold had mono and poly panels of the same wattage that were exactly the same size. About 5 years ago there was a big improvement in efficiency where a typical 295 - 305 watt panel was 72 cells and any 60 cell panel was no more than 260. All of a sudden you were seeing 340 - 360 watt panels in a 60 cell package. True they were mostly monos in that higher wattage but I suggest your same wattage panels are different in age and cell count. If that's the case you might want to check the voltage specs on the larger panels. They are probably higher voltage and lower amperage.

 

[SeaGal]

Price is always my first consideration whether it be solar equipment, cars or women.

Never be afraid to haggle over price!

Oh My God!

Do you actually think you're funny or do you just get a kick from winding people up?

 

[sunshine_eggo]

Price is always my first consideration whether it be solar equipment, cars or women.

So... you're a John now?

 

[Partimewages]

So... you're a John now?

Nope just a big Richard

 

[Solarcabin Channel]

So... you're a John now?

Funny coming from a guy that said "have to keep my wife happy with this shit"

Everything comes with a price!