Solar Panel Comparison (Using PV SOL)

[Donk]

Hi all,

I thought I'd run a simulation on some different makes of panels, in case someone has trouble deciding what to go for. Results are based on annual production (AC side) , panels are all mono (unless specified) and the variables are as follows:

System size: 4kWp (or there abouts)
Inverter: Power-One 3.6
Location: Dartford
Orientation: South (180°)
Pitch: 30°

If anyone has any requests, I'm happy to add more system results (provided the panels are on PV SOL), results are posted from best at the top, worst at the bottom. List is small for now but will grow as the requests come in!

SunPower 327w:
3,777.6 kWh

Phono 250w:
3,770.5 kWh

Solarworld 250w:
3,723.2 kWh

Seraphim 250w (P):
3,706.1 kWh

Canadian 250w:
3,700.0 kWh

Schüco 250w (P):
3,676.6 kWh

Q-Cell 250w (P):
3,628.2 kWh

LG 250w:
3,620.1 kWh



If you'd like to see a particular panel added, let me know and I'll do a test as soon as I can. If you'd like a particular test carried out with different variables I'd be more than happy to do so, just PM me.

Thanks

 

[The Solar King]

Change the inverter and you may get different results. Is the irraidiance data from PVSol or imported from PVGIS?

PVSol works off the data supplied by the panel manufacturers and will relate to panel efficiency.

We find that PVSol tends to underestimate against actual by around 10%. (I know Solar City has some data). Using this alongside the flawed MCS method means customers are never disappointed at real life system output.

Where PVSol really scores is in it's calculation of the impact of shading. Panel and inverter match can make a difference. PVSol does not simulate shade mitigation techniques such as SMA'a Optitrac or similar found on other inverters.

Real life performance is very location specific. I have a customer in East Lothian in a coastal town whose 4kWp system produced over 4000kWh in its first year, blowing away the PVSol and MCS calculations. Fifteen miles away I have another customer with the same equipment and better roof pitch getting around 945kWha/kWp.

At the end of the day you would need the panels side by side on a roof to really know the relative performance of each. There is some work of this kind ongoing at the National Solar Centre in Cornwall. There is also work ongoing to better establish real life performance.

The investment model for solar farms in the south of England is based on outputs of 1000kwha/kWp, which is more than the figures above. The other difference will also be panels placed at optimum angle (about 38 degrees).

As always panel performance is only part of the story. PVSol is excellent software but is still only a simulation and estimation of performance.

 

[Donk]

I'm well aware of the conservative results PV SOL produces, these tests are there just to show a comparison for a standard system 4kWp system. By running a simulation using the same variables, the aim of my post is just to provide a snapshot view of how panels perform against each other.

I think you've thought a little bit too much into what I was aiming to do here...

 

[The Solar King]

The issue is all it does is to tell you the relative comparitor in the software simulation. The point I am making is this may not be what you then experience is real life. The fact that a panel shows greater output in PVSol does not mean this will be the case in a real life situation. Matching panel to inverter is also important.

I am not quite sure what you are aiming to do. The whole point of the software is to allow evaluation given the site specific constraints and conditions each individual case presents. Following accurate site survey, your skill as a user of the software is to optimise both configuration on the building and choice of equipment. Correct use of the financial model will then allow full evaluation to assist in informed decision making as to the efficacy of any given proposal.

We played around with the software in the way you have when we first got it and concluded it was a blind alley.

 

[Donk]

The only way to get an exact figure is as you say, to have the panels side by side. This is obviously not a viable option hence why as MCS certified companies, we are required to carry out system designs for each job. This is the next closest possible avenue to compare panels, it is just supposed to be a bit of fun and show basic comparisons against different panels, unless you can think of a more accurate way (without physically lining up panels)?

 

[The Solar King]

My worry is that anyone viewing this without understanding all the constraints involved may draw the conclusion that panel X is better than panel Y because within your comparison it shows panel X has a greater output within the scenario used.

Within the MCS output estimation method, panel performance and output characteristics are not considered, which is one of its shortcomings.

What is important in everything we do especially on a forum like this is to ensure nothing can possibly mislead those with less expert knowledge than we have.

We have disclaimers with output estimations due to the number of variables even beyond those stated in the disclaimer that can create differences. I find this lack of precision frustrating, but it is something we have to live with. I use PVSol to attempt to lessen the variability for a given installation. GavinA uses his own methodology where he even guarantees output - he hasn't come unstuck yet!

Either look at the Photon test results or wait for the results of the work being undertaken at the NSC.

 

[Donk]

Nothing I posted is intended to mislead anyone, but you cant ignore the fact that some panels are better than others, hence why such programs exist to compare. I could change the variables of the above system and it could completely change the table, hence why I made it clear on the variables used. Disclaimers for estimations are to protect the installation company from a backlash when they sell a system but it's a crappy year for generation, not for pitching panels against each other.

You and I both know what panels are better and which are worse, giving basic information to the public isn't a problem. If you feel strongly enough about it, perhaps you'd feel at ease if I stick a disclaimer at the bottom of my post?

 

[Unregistered]

Wow, I really found this useful. Thank you for your help Donk.
There are so many panels on the market it is great to be able to compare them on a performance basis (at the end of the day this is my greatest concern over aesthetics). Keep up the good work.

 

[Dan]

Don't mind me while I bump some threads in the solar PV forum. If they're not current or applicable topics, just ignore the threads; they'll drop off the page. If they are, feel free to chip in and chat solar stuff in the solar panels forum.

 

[f0ster]

when using pv-sol you need to check the panel data against manufacturers data sheet. I recently had an issue where the data in pv-sol was incorrect, it made the panel look extremely good until I corrected the data.