Admin vs Streetsleeper Solar Shootout

Phil

Forum Admin
#1
For those that have been following mine and Rae's solar upgrades, you will know we have gone for different methods of getting our batteries charged. Here are our setup specs:

Admin

4 x LG Neon2 320 watt solar panels mounted flat on the roof.
85 amp Victron MPPT controller

1280 watts total of solar panels

Streetsleeper

2 x Panasonic 245 watt solar panels mounted so that they can be angled towards the sun.
50 amp Victron MPPT controller

490 watts total of solar panels


As both the MPPT controllers have Bluetooth I was able to get live data from both vehicles and take screenshots on my phone. You can see by the time in the top left that the photos are taken at the same time.

These photos are taken on 28th December 2018 in Hereford, this is only a week past the shortest day so the sun is still at nearly its lowest point on the horizon.

Here is a photo of how the motorhomes were parked, the photo shows Rae's panels positioned towards the sun. The photo was taken at 10:50 when the sun was now shining on the panels.



IMG_0298.jpg


Overcast readings at 10:32

The first readings are without direct sunlight on the panels the sunlight is being diffused by the clouds so I would expect a better output from my panels.

IMG_0281.png IMG_0280.png

Looking at these readings I am producing 114 watts from 1280 watts of panels (8.91% of max output) and Rae is producing 65 watts from 495 watts of panels (13.3% of max output).


Direct sunlight at 10:42

Now we have direct sunlight on the panels, the sun is very low and is just clearing the buildings

IMG_0285.png IMG_0284.png

Looking at these readings I am producing 201 watts from 1280 watts of panels (16.4% of max output) and Rae is producing 322 watts from 495 watts of panels (65.05% of max output).

Direct sunlight at 10:42

Now we have direct sunlight on the panels, the sun is very low.

IMG_0305.png IMG_0306.png

Looking at these readings I am producing 301 watts from 1280 watts of panels (23.52% of max output) and Rae is producing 396 watts from 495 watts of panels (80.00% of max output).

Before I could take the next reading Rae's lithium batteries has reached full charge so the solar output was now only 1 watt. This was impressive as he had already had six cups of tea using the electric kettle!


The Results

Even at 11 am Rae's panels were producing 80% of their rated output, whereas my panels were only producing 23.52%. This means that in direct sunlight in the Winter Rae's installation is definitely the winner.

We will both be stewarding a meet on the 21st June so we will take some more reading at midday and I am guessing that although I will have a higher charge rate Rae will still be getting great efficiency from his panels.

The Conclusion

If you can install your panels like Rae's so that they can be angled then you should. You will get much better output in the Winter which is after all when we really need to extra amps.
 


#2
That’s superb Phil can’t wait to get mine changed over so they can tilt .Just waiting for the bloody rose joint so I can mount them well done guys
 


jagmanx

Full Member
#3
Useful info
Obviously the tilting solution is best.
Especially in winter (as posted)
And when the panels are flat because you are travelling the alternator kicks in.

Game set and match (IMO)
 

wildebus

Full Member
#4
Great Info there.
Raes panels seem to be really good.
It would have been very interesting to have a side-by-side comparision with Rae's panels flat as well to have a benchmark for tilt vs. non-tilt on an identical setup.
 

runnach

Full Member
#5
Fantastic piece of data collecting. I have long thought about having panels that tilt. Problem is getting the time to do such a task. That said, I have looked at fabbing up a tilting device, that can be operated by opening small roof light over rear fixed bed.

I also need to check how efficient current BP made panels are, I have no idea when they were installed??
 
#6
Thank you Phil for posting that. I never once thought the figures would be so impressive; I knew tilting the panels would make some difference but nowhere near what the figures show. I can now continue with the next part of the solar upgrade which will be the compressor fridge but, in the meantime, because of the positive results I will go ahead and fabricate an electronic device that will lift and lower the panels rather than me getting on and off the roof.

Rae
 


St3v3

Full Member
#8
I will go ahead and fabricate an electronic device that will lift and lower the panels rather than me getting on and off the roof.

Rae
Rae, I'll go and dig out those actuator details now :)
 
#10
Could be you going up rear ladder and setting the panels to the correct azimuth. o_O
No point Terry, I'm useless with directions so who knows which way they'll be pointing :LOL:
 


#11
That backs up my assertions about the improved ability of a tilted (or in my case freestanding) Solar Panel in Winter. It is gratifying to read the results Phil, thanks for the posts. Maybe now I will not be regarded as a liar.
 

runnach

Full Member
#13
That backs up my assertions about the improved ability of a tilted (or in my case freestanding) Solar Panel in Winter. It is gratifying to read the results Phil, thanks for the posts. Maybe now I will not be regarded as a liar.
Anyone who may of suggested the way you setup your array when parked up is wrong, knows nothing about what is best method to harvest solar power!

You still use the stick jig Jim?
 
#14
There's a very easy way of achieving the right angle and position of the solar panel, a piece of white paper is placed at the top face of the solar panel and attached to that is the lid of an aerosol can, when you get no shadow you've got it right.

Rae
 


Wully

Full Member
#15
I’ve seen Raes set up first hand well impressed Very tidy job I liked the wind turbine idea too but just gose too show if you’ve got the the technical ability that Rae has and the technology side that Phil has you can do stuff like this. 👍
 


#16
if you’ve got the the technical ability that Rae has and the technology side that Phil has you can do stuff like this. 👍
Thank you Wully for that, I just drill holes and saw straight, the rest is left to the big fella.

Rae
 


#17
Yes Terry, after months of testing I came up with the solution for maximum performance.

Summer ... short stick.

Winter ... long stick.
 


Okta

Full Member
#18
Very interesting. If you get the opportunity could you possibly repeat the tests on a cloudy day? ( Cheeky request )

I find the solar angle calculator on this page http://solarelectricityhandbook.com/solar-angle-calculator.html helpful and interesting. It suggests panels hung vertically on the side of the van would catch more sun than flat on the roof at this time of year. However, I guess flat on the roof avoids having to aim them at the sun and possibly catches more early morning and evening sun than a South facing one. I also wonder what happens on the more common cloudy days when the brightest bit of sky might be directly above and not on the horizon. I think this possibly happens because light passes through more cloud at an angle than it does from directly above. All guess work, I wish I knew the answer.
 
#19
You only need to look at solar farms to see that angled panels is the way to go.
 


#20
On a cloudy day the freestanding (or adjustable) panels are best laid flat, in other words there is no advantage to raise them.

There is also no need to constantly adjust the panels during the day, every 4 hours is usually enough for close to maximum gain. It is also incorrect to point the panel directly at the Sun, this can result in a slightly lower harvest of power. This is because on a hot Summer day the panel itself absorbs heat and functions less well. The difference is not big and will not last long as the Sun is moving slowly.

The above comments are not guesswork, they are my observed results over a number of years using a freestanding panel and a digital Ammeter to check results.
Very interesting. If you get the opportunity could you possibly repeat the tests on a cloudy day? ( Cheeky request )

I find the solar angle calculator on this page http://solarelectricityhandbook.com/solar-angle-calculator.html helpful and interesting. It suggests panels hung vertically on the side of the van would catch more sun than flat on the roof at this time of year. However, I guess flat on the roof avoids having to aim them at the sun and possibly catches more early morning and evening sun than a South facing one. I also wonder what happens on the more common cloudy days when the brightest bit of sky might be directly above and not on the horizon. I think this possibly happens because light passes through more cloud at an angle than it does from directly above. All guess work, I wish I knew the answer.
 


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