I have two 155W solar panels on my caravan roof and wanted to add another. As I couldnt get one of the same make from the van manufacturer I bought a 175W Victron panel which has very similar specifications. However, Victron do not make solar panels so it will have been rebranded from another manufacturer.
It arrived Sunday and so yesterday being a beautiful cloudless day, not that that means too much in regard to obtaining maximum solar output, with a temperature of 26C I tested my panel angled directly towards the sun.
Maximum achieved was 149W or 85% of rated output.
-- Edited by TimTim on Tuesday 6th of December 2022 09:17:09 AM
I have two 155W solar panels on my caravan roof and wanted to add another. As I couldnt get one of the same make from the van manufacturer I bought a 175W Victron panel which has very similar specifications. However, Victron do not make solar panels so it will have been rebranded from another manufacturer.
It arrived Sunday and so yesterday being a beautiful cloudless day, not that that means too much in regard to obtaining maximum solar output, with a temperature of 26C I tested my panel angled directly towards the sun.
Hmm TimTim interesting to see the MPPT regulator at work there. Panel output 17.52 V @ 8.5 A battery input 12.30 V @ 11.80 A. If it was a PWM regulator it would be giving 12.3 V @ 8.5 A =105 W. Just saying for those not yet converted.
I am always slightly amused by the level of accuracy in these ordinary quality meters for punters to look at. Giving the impression of super accuracy. Like most multimeters. Giving figures to 4 significant digits or more. Hmm !!
-- Edited by Jaahn on Tuesday 6th of December 2022 09:24:43 AM
I notice that the "number of cells in series" is wrong for the 175W panel and above.
-- Edited by dorian on Tuesday 6th of December 2022 09:55:12 AM
Mike Harding said
10:57 AM Dec 6, 2022
My understanding is that solar panels are qualified by a standard (perhaps IEC61215) and, iirc, that specifies their output be measured at an illumination level of 1000W/m2 and that is likely what Victron mean when they rate the panel at 175W.
Unless you know the level of illumination (and probably the frequency mix) hitting the panel then any measurement you make is meaningless.
dorian said
11:17 AM Dec 6, 2022
Mike Harding wrote:
My understanding is that solar panels are qualified by a standard (perhaps IEC61215) and, iirc, that specifies their output be measured at an illumination level of 1000W/m2 and that is likely what Victron mean when they rate the panel at 175W.
Unless you know the level of illumination (and probably the frequency mix) hitting the panel then any measurement you make is meaningless.
I think you'll find that the standard is an accurate reflection of the real solar irradiance at the earth's surface.
Average annual solar radiation arriving at the top of the Earth's atmosphere is roughly 1361W/m2.[32] The Sun's rays are attenuated as they pass through the atmosphere, leaving maximum normal surface irradiance at approximately 1000W/m2 at sea level on a clear day. When 1361 W/m2 is arriving above the atmosphere (when the sun is at the zenith in a cloudless sky), direct sun is about 1050 W/m2, and global radiation on a horizontal surface at ground level is about 1120 W/m2.[33] The latter figure includes radiation scattered or reemitted by the atmosphere and surroundings. The actual figure varies with the Sun's angle and atmospheric circumstances. Ignoring clouds, the daily average insolation for the Earth is approximately 6 kWh/m2 = 21.6 MJ/m2.
Mike Harding said
11:42 AM Dec 6, 2022
I'm quite sure that when they wrote the standard that is what they endeavoured to do. However the earth is a big place and the atmosphere varies from place to place and day to day and without calibrated measurement gear there is no way of assessing how much of the light specified in the standard is falling on the panel. I would not have thought this was a point to be debated?
TimTim said
02:08 PM Dec 6, 2022
Thats the one Dorian and yes I see what you mean regarding the number of cells in the table.
Whenarewethere said
09:12 PM Dec 6, 2022
TimTim wrote:
with a temperature of 26C I tested my panel angled directly towards the sun.
Maximum achieved was 149W or 85% of rated output.
What gauge wire & length (both + & -) are you using.
It may be 26°C but are you getting enough air circulation for cooling.
Might be interesting to see what you can squeeze out of them with water cooling.
I have no trouble getting 125 watts out of 120 watts Projecta panels on a good day, & with water cooling 137 watts.
TimTim said
06:18 PM Dec 7, 2022
It was a test WAWT. Panel propped up to provide angle to the sun with plenty of ventilation. Cable 8AWG just 200mm from panel ables to controller and another 200mm to battery.
Funny enough I did sprinkle the panel with water to see it there was any effect and the output didnt change.
Sounds like your 120W panels are excellent. What are their dimensions?
Whenarewethere said
06:46 PM Dec 7, 2022
The Projecta 20 watt solar panel's overall size is 638 x 278mm. Foot print of actual cells is 582 x 237mm, so 78% of the panel area, not brilliant.
So 113 watts per square metre, actually a whisker less allowing for a few mm for hinges between the 6 panels.
Pretty inefficient, but at least they produce what they say.
6 x 20 watt.
I sprayed them with a hand trigger sprayer when testing with water cooling.
The reason I used these panels was simply they had to fit in a space.
I have two 155W solar panels on my caravan roof and wanted to add another. As I couldnt get one of the same make from the van manufacturer I bought a 175W Victron panel which has very similar specifications. However, Victron do not make solar panels so it will have been rebranded from another manufacturer.
It arrived Sunday and so yesterday being a beautiful cloudless day, not that that means too much in regard to obtaining maximum solar output, with a temperature of 26C I tested my panel angled directly towards the sun.
Maximum achieved was 149W or 85% of rated output.
-- Edited by TimTim on Tuesday 6th of December 2022 09:17:09 AM
Hmm TimTim interesting to see the MPPT regulator at work there. Panel output 17.52 V @ 8.5 A battery input 12.30 V @ 11.80 A. If it was a PWM regulator it would be giving 12.3 V @ 8.5 A =105 W. Just saying for those not yet converted.
I am always slightly amused by the level of accuracy in these ordinary quality meters for punters to look at. Giving the impression of super accuracy. Like most multimeters. Giving figures to 4 significant digits or more. Hmm !!
-- Edited by Jaahn on Tuesday 6th of December 2022 09:24:43 AM
Is this the one?
https://www.victronenergy.com/upload/documents/Datasheet-BlueSolar-Monocrystalline-Panels-EN.pdf
I notice that the "number of cells in series" is wrong for the 175W panel and above.
-- Edited by dorian on Tuesday 6th of December 2022 09:55:12 AM
My understanding is that solar panels are qualified by a standard (perhaps IEC61215) and, iirc, that specifies their output be measured at an illumination level of 1000W/m2 and that is likely what Victron mean when they rate the panel at 175W.
Unless you know the level of illumination (and probably the frequency mix) hitting the panel then any measurement you make is meaningless.
I think you'll find that the standard is an accurate reflection of the real solar irradiance at the earth's surface.
https://en.wikipedia.org/wiki/Solar_irradiance#Irradiance_on_Earth's_surface
Average annual solar radiation arriving at the top of the Earth's atmosphere is roughly 1361 W/m2.[32] The Sun's rays are attenuated as they pass through the atmosphere, leaving maximum normal surface irradiance at approximately 1000 W/m2 at sea level on a clear day. When 1361 W/m2 is arriving above the atmosphere (when the sun is at the zenith in a cloudless sky), direct sun is about 1050 W/m2, and global radiation on a horizontal surface at ground level is about 1120 W/m2.[33] The latter figure includes radiation scattered or reemitted by the atmosphere and surroundings. The actual figure varies with the Sun's angle and atmospheric circumstances. Ignoring clouds, the daily average insolation for the Earth is approximately 6 kWh/m2 = 21.6 MJ/m2.
I'm quite sure that when they wrote the standard that is what they endeavoured to do. However the earth is a big place and the atmosphere varies from place to place and day to day and without calibrated measurement gear there is no way of assessing how much of the light specified in the standard is falling on the panel. I would not have thought this was a point to be debated?
Thats the one Dorian and yes I see what you mean regarding the number of cells in the table.
What gauge wire & length (both + & -) are you using.
It may be 26°C but are you getting enough air circulation for cooling.
Might be interesting to see what you can squeeze out of them with water cooling.
I have no trouble getting 125 watts out of 120 watts Projecta panels on a good day, & with water cooling 137 watts.
It was a test WAWT. Panel propped up to provide angle to the sun with plenty of ventilation. Cable 8AWG just 200mm from panel ables to controller and another 200mm to battery.
Funny enough I did sprinkle the panel with water to see it there was any effect and the output didnt change.
Sounds like your 120W panels are excellent. What are their dimensions?
The Projecta 20 watt solar panel's overall size is 638 x 278mm. Foot print of actual cells is 582 x 237mm, so 78% of the panel area, not brilliant.
So 113 watts per square metre, actually a whisker less allowing for a few mm for hinges between the 6 panels.
Pretty inefficient, but at least they produce what they say.
6 x 20 watt.
I sprayed them with a hand trigger sprayer when testing with water cooling.
The reason I used these panels was simply they had to fit in a space.