The 25C temperature specification is the panel temperature, not the ambient temperature. At 25C ambient, the panel might be at 50C or higher. Proper specifications will also include the degradation rate in performance at higher temperatures.
The "1,000W/m2" is the standard light intensity. In real life it will typically be less. A specification at 800 is useful, but rarely provided.

"Honestly" specified panels will typically produce between 150W (typical good quality) and 240W (top of the range and expensive panels from known top of the range manufacturers using the best cells available) per square metre at the standard conditions. If they claim greater than 200W it is probably false claim. Many are not true to label.
The example panel is 1030 x 680mm = 0.7M2. I would expect its real performance (at standard test conditions) to be between 100 and 140W. I doubt that there is a commercial panel anywhere in the world this size that will produce 200W.

There will be further losses in the cables and the controller.

The appropriate Vmp for any application will depend on the way the panels are wired and the type of controller used. Using panels with inappropriate Vmp will reduce actual yield.
Cheers,
Peter

I take it your referring to the Frame size: Anodized Aluminium Alloy?

Yes I know Yall,

The 25° Celsius is referring STC is an industry-wide standard to indicate the performance of PV modules and specifies a cell temperature of 25°C and an irradiance of 1000 W/m2 with an air mass 1.5 (AM1.5) spectrum. These correspond to the irradiance and spectrum of sunlight incident on a clear day upon a sun-facing 37°-tilted surface with the sun at an angle of 41.81° above the horizon.

However  I am trying not confuse everyone looking at Solar Panel purchasing or updating with technical jargon just trying to help them, with details which will assist them to make an informed decision.

I could write a thesis on all the variables and merits Poly vs Mono solar panels, of MTTP vs PWM Solar Controllers there overall performance based upon the solar panels positioning and adding in Wire sizing AWG (American Wire Gauge)  sizing based upon the distance from the Solar Panel to the Solar Controller. The merits of Parallel vs Series connection of Panels and amperage differences and wire required depending upon the Volts. 

But I didn't I just put forward a simple way in which a novice looking at Solar Panel might be able to compare Apples to Apples, I didn't want to go into Solar Controllers or sizing them based upon where your permanently fitting them to a roof of your RV or ground based which you change the angle hourly to face the Sun and the above paragraph. The ambient temperature of the coldest place which they will visit and the effects that this will have on their solar power production.

Just a simple means of comparison Brand A vs Brand B 

Ken,

Why thank you for your detailed analysis of the Solar Panel Specifications, what's wrong!

I put up a KIS solution for people who maybe be looking to purchase Solar Panels, but for some weird reason people have it in themselves to tear it down and confuse people with jargon.

Really if someone asked how can I compare Solar Panels, you'd leap into telling them Modulel sizing and cell irradiance. But what if they had 5 busbars, 4 busbars  or 3 busbar, what if the technology allowed for overlapping the cells a new technology! your unaware off.

Incidentally the spec's are a Chinese Manufacturer of thin film technology developed through their German Subsidiary, so here's a quick blurt on thin film Technology not from their site.

Thin-film cells are laminated to make the later module more robust and resistant against weather or other environmental impacts. They can be produced either in single-junction or multi-junction configurations.

While the single-junction configurations involve only one cell and only cover one part of the solar spectrum, the multi-junction configurations refer to combined sets of single thin-film cells.

These use different parts of the spectrum from their respective angle to jointly convert the respective portions into electricity, thus using a much larger range of the input of sunrays.

Seriously instead of picking on things to pull down, why not come up with a better way in which a novice could compare Solar Panels and what to look out for.

Ram Man wrote:

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Ken,

Why thank you for your detailed analysis of the Solar Panel Specifications, what's wrong!

I put up a KIS solution for people who maybe be looking to purchase Solar Panels, but for some weird reason people have it in themselves to tear it down and confuse people with jargon.

-------------------------------------

Seriously instead of picking on things to pull down, why not come up with a better way in which a novice could compare Solar Panels and what to look out for.

-----------------------------------------------------------------------------------------------------------------------------------------------------------------Ram Man  

 

 Hi Ram Man 

I could say welcome to the forum but perhaps you do not feel welcome and seemed to be a bit peeved.  It is a public forum and people can post their thoughts within the rules. I guess I was surprised that for a first post you came on and chose to post about something technical that I thought might have missed some of the important things to look out for. So I added what I personally have found out and commented on what Peter had said which I also though should be said. Some of the other posts may have been peripheral IMHO.

I regularly post on this forum and have always attempted to help people and comment when I see it is appropriate and share my experience on solar. Indeed several members have chosen to PM me for a discussion on their ideas or problems and thanked me for my help. I usually tell people to look on this part of the forum and do some reading and make an assesment of the worth of the postings. I will still continue to do that including your post. 

 I have also recommended that people buy a good book by Colyn Rivers on Solar out of the several he has written. But most people seem to think that investing ~$40 is a waste of money even though they may spend a thousand (or more if using lithium) on things recommended on a forum and posted by people they do not know, or even by some commercially inclined business who they do not know either ?? Strange ! IMHO 

Jaahn   

Hi Ram Man,

 I am sorry if I upset you by pointing out an inconsistency in the panel specifications you posted, which should be questioned.

 Perhaps a better example would be the one shown below from a local supplier : Lowenergydevelopments.

As you can see the surface area of the module is 1.27 m2 (1.58 x 0.808m). The actual cell area would be somewhat less.

Using the Standard Test Conditions Solar Irradiance of 1000w/m2 as specified then the incident solar power on the surface area of the panel is 1270 W

Then using the minimum specified cell efficiency of 16.8%, the panel output would be 213W.  but actually somewhat less because cell area is less than panel surface area.

In this case the calculated power of 213W is consistent with the published specifications.

This was not the case with the specifications you originally posted, which calculated to aprox 120W (not 200W) at the specified and realistic efficiency of 17%. 

Certainly cell efficiencies are improving, but irrelevant in this case as the efficiency was quoted as 17%

I have no disagreement with the general thrust and motive for your original post

 The key to making good decisions is an understanding of specifications, and how to interpret them - not blind faith.

 Two mottos should be :

 Question Everything  together with   Dont believe everything you are told and especially what you tell yourself

ModelPANEL200W-12V

Ken

Ram Man wrote:

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Hi Dorian,

Well maybe you could write up something on how to compare Solar Panels , you recommend a book . . .

 

---

You have me confused with someone else.

I often profess my ignorance of this subject and I have many more questions than answers. I certainly don't have any relevant experience other than my residential, rooftop, grid connected solar system. Currently I'm just a spectator, not a participant. I enjoy the threads for their technical information (especially the teardowns), even if they may become a little too "passionate" at times.

BTW, just in case it wasn't clear, I am not blaming you for picking a flawed spec sheet. That was just bad luck. I confess that I didn't see the inconsistency until it was pointed out by others.

kgarnett wrote: Ken has added Great information on What to Know about Solar Panel Spec's 

---

Hi Ram Man,

 I am sorry if I upset you by pointing out an inconsistency in the panel specifications you posted, which should be questioned.

 Perhaps a better example would be the one shown below from a local supplier : Lowenergydevelopments.

As you can see the surface area of the module is 1.27 m2 (1.58 x 0.808m). The actual cell area would be somewhat less.

Using the Standard Test Conditions Solar Irradiance of 1000w/m2 as specified then the incident solar power on the surface area of the panel is 1270 W

Then using the minimum specified cell efficiency of 16.8%, the panel output would be 213W.  but actually somewhat less because cell area is less than panel surface area.

In this case the calculated power of 213W is consistent with the published specifications.

This was not the case with the specifications you originally posted, which calculated to aprox 120W (not 200W) at the specified and realistic efficiency of 17%. 

Certainly cell efficiencies are improving, but irrelevant in this case as the efficiency was quoted as 17%

I have no disagreement with the general thrust and motive for your original post

 The key to making good decisions is an understanding of specifications, and how to interpret them - not blind faith.

 Two mottos should be :

 Question Everything  together with   Dont believe everything you are told and especially what you tell yourself

 

 

ModelPANEL200W-12V

Maximum power (W)	200
Optimum power voltage (Vmp)	18.2
Optimum operating current (Imp)	10.99
Open circuit voltage (Voc)	22.0V
Short circuit current (Isc)	12.12A
Solar cell: (mm)	125 x 125
Number of cell (pcs)	12 x 6
Size of module (mm)	1580 x 808 x 35
Front glass thickness (mm)	3.2
Connection lead length (mm)	approx 900
Connection type	MC4
Shading protection	3x diodes
Max DC string voltage (V)	1000
Cell type	Monocrystalline
Temperature range (°C)	-40 to +85
Tolerance wattage (%)	+/- 3%
cell efficiency	>16.80
Surface maximum load capacity (Pa)	2400
Allowable hail load	23m/s, 7.53g
Frame	Anodized Aluminium Alloy
Weight per piece (kg)	14.2
Standard test conditions	AM1.5, 1000W/m2, 25°C (+/-2°C)
Frame color	Silver

Ken

 

-- Edited by kgarnett on Saturday 2nd of May 2020 11:16:25 PM

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DeBe wrote:

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Jahhn. One of the reasons there's a lot of second hand solar panels (house type) is that solar installers refuse to use the older panels for an upgrade in size, even if they are still quite good. Its also very hard to even find an installer that will fit a second hand setup. Generally it all comes down to money. Prices for good second hand panels is $50 each or much less or even free.

 

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 Hi DeBe 

Bargains ar'nt they. I have quite a few in the yard.  The installers give lots of reasons why they cannot use them, mostly BS. Money yes ! But it is true that the old ones are not on the approved list for grid connect. But no problem for battery connect !!

If you use a proper MPPT controller you can use the smaller panels two in series and then parallel strings or the higher voltage larger ones just in parallel strings and both ways give great results for minimal cost. And you can get significant charge in low sun or overcast situations. The quality Aussie made old panels put out almost their sticker current too under test.

There are crap cheap chinese panels on roofs that are failing so be careful and inspect and test them. I looked at a set for a friend that only one out of 10 was working properly?? But you could see the corrosion, bad connections, faulty cells and defects by eye. Just as a note the original supplier of those was out of business by then so the 10 year warranty was useless. 

Jaahn     

Whenarewethere wrote:

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Even though my setup is tiny, 6 x 20 watt panels. The panels were a small percentage of the overall cost. I just can't see the point fluffing around to save a few dollars & end up with a third rate system.

Do it right, the cost is amortised over many years & it will more than likely be cheaper in the long run.

---

 Hi 

You are entitled to your opinion but I am happy with mine. I do not consider the systems I use(d) are third rate or second rate but first rate and work as good as they should.  I guess it is just a matter of having confidence in my ability to get quality gear at a good price.  If you cannot do that then buy new and from expensive quality places. I choose to spend my money other ways. Horses for courses.

I fail to see the logic of this statement "it will more than likely be cheaper in the long run" but please do not justify it. Similar to the "you get what you pay for" statement i see used on here occasionally. My problem is I guess I was born poor and tried to stay that way. 

Jaahn