Difference in solar panel quality

[Oscarpop]

I found these on the interweb

http://www.solarpanelpvt.com/100w-semi-flexible-monocrystalline-solar-panel.html

These are about 20% of the costs of the posh Italian ones.

Is there that much difference in quality?

 

[LadyInBed]

Is there that much difference in quality?

From all that has been said on the forum I have come to the conclusion that it is a case of 'suck it and see'!

 

[NB Willawaw]

It's hard to fully compare without a detailed spec but most solar panels are made in China. Are you sure the Italian ones aren't just badged. Even if their performance and durability aren't quite as good, does it matter ?

I tend to view solar panels like batteries - with a finite life and slightly sacrificial.

 

[Fosdyke Wash]

Solarpanelpvt.com 100W semi-flex panel

Just took delivery of a 100w semi-flexible panel from Solarpanelpvt.com (the one in the OP's link).

It didn't come with any instructions (or wiring) but should be straightforward to set up. The corners are sharp and the box with the connector block will need to be sealed with Sikaflex, once wired.

My five-year old 34W "premium brand" panel has rusted badly at the edges (horrible deck stains) and the wires in the connection block have corroded to the point of disintegration.

At three times the output and one third the cost, the new one's looking good...

 

[MM5AHO]

I noted that they say it will put 5 amps back into the battery every hour.
I wonder what they mean by this?

Surely time isn't relevant in amps? It would do 5 amps every second too!

If it does 5 amps, at 12 Volts, that doesn't appear to be 100 watts. Maybe it runs higher voltage, say 17V to get 100W.?

 

[Cardo]

Just took delivery of a 100w semi-flexible panel from Solarpanelpvt.com (the one in the OP's link).

It didn't come with any instructions (or wiring) but should be straightforward to set up. The corners are sharp and the box with the connector block will need to be sealed with Sikaflex, once wired.

My five-year old 34W "premium brand" panel has rusted badly at the edges (horrible deck stains) and the wires in the connection block have corroded to the point of disintegration.

At three times the output and one third the cost, the new one's looking good...

Do let us know how you get on. I've been eyeing up that panel to stick on top of our new bimini.

 

[wotayottie]

I noted that they say it will put 5 amps back into the battery every hour.
I wonder what they mean by this?

Surely time isn't relevant in amps? It would do 5 amps every second too!

If it does 5 amps, at 12 Volts, that doesn't appear to be 100 watts. Maybe it runs higher voltage, say 17V to get 100W.?

In use on your boat it isnt a 100 watt panel. You cant charge safely at more than 15v and even if you achieved the maximum am perage they say at this figure it would be 80 watts. Buit you wont achieve the maxiumum amperage because that is only available at 19 v output.

And all that is before you take into account everything from the panel temperature to the time of day and of year and the inclination etc.

 

[Fosdyke Wash]

Solarpanelpvt - technical label data

This afternoon (cloudy and dull) and with the protective film still in place, the panel was showing 18V through the meter. Amps - negligible.

The data label reads:

Max power - 100W
Max power voltage - 18.97V
Max power current - 5.28A
Open circuit voltage - 22.76V
Short circuit current - 5.69A
Net weight - 3.1kg
Size - 1250 x 550mm [2.75mm thick]
STC - 1000W/m2, AM1.5, 25degC

It's also marked "Made in China - www.sinosola.com"

My cruising consumption is usually between 1.5 and 2amps. Anything above that will be a bonus...

 

[William_H]

This afternoon (cloudy and dull) and with the protective film still in place, the panel was showing 18V through the meter. Amps - negligible.

The data label reads:

Max power - 100W
Max power voltage - 18.97V
Max power current - 5.28A
Open circuit voltage - 22.76V
Short circuit current - 5.69A
Net weight - 3.1kg
Size - 1250 x 550mm [2.75mm thick]
STC - 1000W/m2, AM1.5, 25degC

It's also marked "Made in China - www.sinosola.com"

My cruising consumption is usually between 1.5 and 2amps. Anything above that will be a bonus...

Your test does not mean much although I suspect with cloudy and dull and with the protective film on it is not functioning very well. The real test is to connect it to a battery and check current into battery.
Your 18v open circuit can be a measure of virtually nothing being generated.

As a matter of interest I have a domestic solar PV array of 1500watts it is currently giving me about 9killowatt hours per day. This in middle of southern summer 32 degrees south.
That could then mean 100watt panel could give about 600watt hrs per day or about 30 amp hours into 12v battery.(possibly a little more with MPPT controller) I doubt you could achieve that in UK summer with panels angled to the sun. But it might give you an idea of what can be hoped for. good luck olewill

 

[Mistroma]

Look at the panel test conditions

Remember that the figures quoted by panel manufacturers are based on standard conditions that you won't achieve in reality.

Label says STC - 1000W/m2, AM1.5, 25degC

1) 1000W/m2
This is approx. the irradiance at the Earth's surface on a panel perpendicular to the Sun's rays at sea level on a clear day. So output will be less if not a perfectly clear day e.g. Sl. hazy. It will also be less if the panel isn't at 90 deg. to the sun.

2) AM1.5
Air mass of 1.5 relates to the amount of air that the sunlight passes through. Less at equator at noon and a lot more in Hebrides in late afternoon (much longer path). You can move the panel to keep at 90deg. to the sun but you can't make the light travel through less air.

3) 25degC
Panel efficiency varies with temperature and drops off as the panel heats up.

The manufacturer says that the panel has a peak power voltage of 18.97V where it delivers 5.28A to give 100W under the conditions stated.

However, you aren't going to get these conditions due to location in UK, panel angle, weather. Even if you did you'd need a very good MPPT contoller to approach 100W. It is more likely that a cheap controller will simply drag the panel Voltage down to 12.6 - 14V and run less efficiently.

All in all, you'd be quite pleased to get 75-80% of the quoted amperage on a sunny day.
Around 4 - 4.2 A

 

[Fosdyke Wash]

Thanks for advice

Olewil and Mistroma
Thanks for your explanations, much appreciated. If it puts out 4A or 30A/day that'll suit me fine - I look forward to wiring it up to the regulator and watching the battery monitor.
Thanks to Oscarpop, too - wasn't aware of this panel 'til I saw your original post...

 

[nigelmercier]

I noted that they say it will put 5 amps back into the battery every hour. I wonder what they mean by this?

They mean that they are talking nonsense.