PHPP values for PhotoVoltaics

[puntloos]

So my builders Solar supplier has provided some inputs to their panels to feed into PHPP. Here's the relevant section:

 

Information from the PV module data sheet for standard test conditions (STC)
Technology 4-Mono-Si 
Nominal current IMPP0 7.78 
Nominal voltage UMPP0 34.48 
Nominal power Pn 268 
Temperature coefficient short-circuit current α 0.040 
Temperature coefficient open-circuit voltage β -0.270 
PV module dimensions: height 1.658 
PV module dimensions: width 0.944

Crucially, the 'Nominal power' says 268, which - assuming this actually is Watt and I understand things correctly this feels really low. Most panels I'm aware of (no idea of actual availability!) are able to reach at least 375W 

 

Am I missing something? Is 268 really a bad panel, unless perhaps it's super cheap for some reason? It is mono-crystalline, so normally that actually means 'good quality'.

 

Anyone have the figures for their panels that are better than the above?

 

 

[Radian]

1 minute ago, puntloos said:

Nominal current IMPP0 7.78

That's a pretty weak module. State of the art in 2012.

[puntloos]

53 minutes ago, Radian said:

That's a pretty weak module. State of the art in 2012.

 

And indeed multiplying Current and Voltage gives you Watt- so that math adds up - about 268. But my designer suspected somewhat that these figures were "measured conservatively" e.g. these are real numbers not boastful numbers that salesmen like to talk about.

 

Back in the day, crappy stereos and speakers advertised that they were "300Watt PMPO" which meant something like "if you feed it 300W for only 0.000001 second it will not catch fire and explode, but 0.000002 seconds and you're going to have to buy a new 300W PMPO speaker..."

 

Hence - anyone have comparable numbers fed into PHPP for a more modern module?

[Radian]

There are only really a handful of PV makers globally and their reputations are as big as their operations are gigantic. It's the one area of Chinese specifications that actually appears to chime with reality.

[SteamyTea]

3 hours ago, puntloos said:

PV module dimensions: height 1.658 
PV module dimensions: width 0.944

Check the size of higher output modules.

 

A quick google pulled up this, a 345W module, but it is H 1.98 W 1.002, so 178W/m²

https://static1.squarespace.com/static/5aa1453f4611a037c22bfb95/t/62b590589b7c74228bb0f616/1656066146918/UKSOL+Poly+72+cell+5BB+345w.pdf

 

The ones you have been quoted are 162 W/m²

So not a great deal of difference

Edited October 28, 2022 by SteamyTea

[Radian]

My 'nothing special' JAM54S30-410W's are 1722 x 1134 so about 210W/m²

[puntloos]

4 hours ago, SteamyTea said:

Check the size of higher output modules.

 

A quick google pulled up this, a 345W module, but it is H 1.98 W 1.002, so 178W/m²

https://static1.squarespace.com/static/5aa1453f4611a037c22bfb95/t/62b590589b7c74228bb0f616/1656066146918/UKSOL+Poly+72+cell+5BB+345w.pdf

 

The ones you have been quoted are 162 W/m²

So not a great deal of difference

Great spot, I missed that. Indeed not a huge difference. Frankly the main thing I seem to struggle with is seeing availability. There's a few panels out there, for example @Radian's panels indeed seem to be Available on Tradesparky - 202quid inc VAT each. Doable. 

[SteamyTea]

4 hours ago, puntloos said:

Indeed not a huge difference.

And you may be able to get an overall larger array with more, smaller modules.

[JohnMo]

Never really seen why people fuss over PV efficiency if you have room to install them.

 

PV efficiency is w per m2, nothing more or less. 

 

BUT - Getting them at a good price, that is the important thing.  They should be cheaper than high efficiency panels, because they are using an older technology.  Another thing to ask, are new - old stock, as some of their 20 year life may have expired.  In that case I would be wanting factory fresh, not something that has been hanging about for a number of years.

[SteamyTea]

28 minutes ago, JohnMo said:

Never really seen why people fuss over PV efficiency if you have room to install them.

Me neither, price per watt installed.

 

The only time module efficiency makes aa real difference is when space is tight.

My roof is 4m wide and 4.5m long, so I can get, if I ever bother, 8 0.995m by 1.65 (ish)m modules on.

Shame there is not a module 2m long.

 

A few years back I was chatting to a timber frame builder who was wetting himself that 'thin film' modules has an efficiency of 18%, don't think he grasped it at all.

[Dillsue]

2 hours ago, SteamyTea said:

Shame there is not a module 2m long.

There could well be. Canadian solar do 450w panels at 2100mm tall so fair chance theres 2000mm panels out there at 400-450w

[joth]

3 hours ago, JohnMo said:

PV efficiency is w per m2, nothing more or less. 

 

This. But also, W/m2 doesn't really matter that much if you're not space constrained. On large new builds like yours you may be more export limit constrained (3,68kW per phase) or budget constrained. Either case getting max W/£ is then the more important goal.

Caveat: if you have loads of space but only a limited amount at the most perfect aspect/pitch then those prime positioned panels you obv want max W/m2

 

(Edit: admittedly the DNO export constraint can be worked around by under sizing the inverter vs amount of PV, or installing approved export limitation equipment, but regardless the W/£ is still the key measure for comparing one panel against another in non-space constrained install) 

Edited October 29, 2022 by joth

[SteamyTea]

38 minutes ago, Dillsue said:

There could well be. Canadian solar do 450w panels at 2100mm tall so fair chance theres 2000mm panels out there at 400-450w

I need to revisit this as I think PV is the best option for reducing my cash outgoings.

I think my going roof integrated I can squeeze in a few more watts (can always put the tray edges under my neighbours tiles, they will never know).

[puntloos]

2 hours ago, joth said:

This. But also, W/m2 doesn't really matter that much if you're not space constrained. On large new builds like yours you may be more export limit constrained (3,68kW per phase) or budget constrained. Either case getting max W/£ is then the more important goal.

Caveat: if you have loads of space but only a limited amount at the most perfect aspect/pitch then those prime positioned panels you obv want max W/m2

 

(Edit: admittedly the DNO export constraint can be worked around by under sizing the inverter vs amount of PV, or installing approved export limitation equipment, but regardless the W/£ is still the key measure for comparing one panel against another in non-space constrained install) 

 

Or if you're "I am a huge computer and electronics nerd" constrained. My best estimate is that my house runs an average of 1000W or 8000kWh per year (which includes modest ASHP and elec car usage) so I'm going to be needing quite a few panels to just reach that based on the assumption I can 1:1 trade with the grid. So while I have a largeish house I am still close to maxing out the roof space (so more efficient panels matter)

 

But yes I am going to have to take a good look at what the optimal dimensions are for the panels (given I need to build them into trays) etc

 

[Dillsue]

Sorry to seem a big negative but if your builders solar installer is offering 268w panels, then you probably want to use a different installer, or fully understand why such a seemingly dated spec of panels is being offered. 

[puntloos]

8 hours ago, Dillsue said:

Sorry to seem a big negative but if your builders solar installer is offering 268w panels, then you probably want to use a different installer, or fully understand why such a seemingly dated spec of panels is being offered. 

 

Yes, it seems like a bit of a 'yellow flag' at least, but I don't know what the rationale was. I'm somewhat surprised that the solar market isnt more uniform with panel sizes but perhaps my designer could *exactly* fit that panel and nothing else.. or the price was so amazeballs.. 

[Dan F]

On 28/10/2022 at 19:28, puntloos said:

Hence - anyone have comparable numbers fed into PHPP for a more modern module?

The PHPP numbers are simply the values from the PV datasheet.  As such, our PHPP has the details of our 365W panels which were high mid-range two years ago.   If the value is 268W then there is nothing conservative about this, either there has been a mix-up or these are pretty bad and/or old panels.

 

They are sligtly smaller than most panels (typlically around 1050mm x 1750mm), but not by enough to make 270W sound very reasonable in 2022.    Are these panels already on the roof?  Can you ask them what panels they are using and why?  Did you get a quote at any stage?

 

 

[puntloos]

2 hours ago, Dan F said:

The PHPP numbers are simply the values from the PV datasheet.  As such, our PHPP has the details of our 365W panels which were high mid-range two years ago.   If the value is 268W then there is nothing conservative about this, either there has been a mix-up or these are pretty bad and/or old panels.

 

They are sligtly smaller than most panels (typlically around 1050mm x 1750mm), but not by enough to make 270W sound very reasonable in 2022.    Are these panels already on the roof?  Can you ask them what panels they are using and why?  Did you get a quote at any stage?

 

 

Thankfully we're not yet at that stage. In fact the roof isn't there yet 😃 

So indeed, going to have to insist on better panels (and perhaps a better supplier)