I had been reading about how in winter vertical or near enough tilt will give the best results in winter in the northern hemisphere.
My ground panels had been only at a slight angle of about 30 degrees. No particular reason for that tilt just a guess when setting up.
There is a treeline of large mature oaks and other comparable size trees in the south facing hedge, with the panels to the north of these, also south facing.
When I first installed the new string the sun was still clearing the trees and was getting pretty maxed out current on my 40A charger on good days.
Now though, with the sun dipped lower in the sky it is behind the trees so partial cover most of the day.
Even the highest current when it isnât even shaded, for the small gaps I noticed only 20A was the best it was outputting. This is what made me think perhaps I am missing out due to the tilt being too steep in the wrong direction now the sun is lower in the sky as I would have expected to still get 40A maxing when there was no shading.
For the most of the time when they are shaded I was getting around 5A
So today to experiment I tilted them almost vertical. Not quite, so they could lean up against the poles I have put in and have strapped them to.
Rigged it up and looked again and to my dismay the shaded output was only at 1.5-2.5A.
I am thinking perhaps having them tilted back more was actually better for these shaded conditions as I have read that you are better having them laying more towards flat when it is shaded because they are able to take in more from the wider area - donât know how it works but that is what I read.
I am wondering though that if it will give me back to peak current when none shaded if it would compensate for the lower shaded rates.
Going to be cloudy now for some days I think so not going to be able to test that theory for a bit.
Shaded is shaded. Unfortunately depending on which way the blocking diodes are set up vs the how it is shadowed it can disable a whole panel. So best to remove the shade as a factor.
Your tilt is most ideally 90° to the sun so whereever that is right now for you. Flat works great in diffused light so through clouds not direct sunlight conditions and equatorial.
Yea I know shaded is always going to reduce but it is a question of how much more I will get in none shaded vs optimising for shaded.
If there are 6 out of 8 hours of the day it is shaded for instance then 2 hours at full power then it is whether I tilt for the full power short bursts or tilt back for the majority shaded. Also must consider if the none shaded will be peak times 11am-2pm or so.
Will continue monitoring closely.
EDIT: Brainwave!: Maybe I can make a modular setup to tilt for shade and tilt up for clear weather! Will wait and see the results of the vertical method to see if it is worth it.
This is in the UK and in winter it is mostly cloudy as well as the tree cover due to low sun in the sky so perhaps 90 degrees is going to be worse overall due to shade being the main situation in these months. Both clouds and trees.
I could run more solar wire 100ft to move the panels up the hill and clear the trees but want to see if it will be necessary or not first. No need if I still met my daily needs even in this poorer output state. I was still breaking even pretty much when they were tilted back, but I also relying on dc charger in van when I drive once per week, so want to see if this will be worse or not but not looking good from the first day!
I still struggle if there are many very cloudy days and get pretty much 0 output. In this case it is still important to get the max output when there is decent solar to replenish the battery in the most efficient time for what may only be a short window of solar.
I was intrigued to try it since they say that near vert is best for winter and I made this new string especially for overpanelling in winter so made sense to at least try it.
Sure. arrange them so it doesnât affect the whole array if possible. Or work out which way they are blocked and try physically orient them to minimise it.
Possibly with reflection. I know reflected light can add to harvest in cities it is a consideration for set up.
My string seems to be producing a fraction of what it was regardless of the position. I was messing around with orientations a lot today until I got tired of it and I could notice no different AT ALL with whatever orientation I had it - if very tilted, almost no tilt, or anything in between.
Before I was getting about 5A on partial cloud days like today but now I only was getting 1.5 to 3A max only for short bursts. No matter which way I tilted it stayed down in these numbers. This is for 1100W panel, but 890W for this string I was messing with.
Donât understand why it has dropped when there was decent rays, albeit behind trees and some clouds but I was in the 4-5A range for similar usually before I started mucking around with them.
I checked with clamp meter and they are still outputting current so donât know what is up.
Maybe just some other reason for lesser solar but canât see what since there were quite some rays through the day and fairly clear with just partial clouds with sun peeking through quite often.
The optimisers Iâm using are Tigo. Some people call this âpartial shading,â others call it âfirewood.â
Iâve got a north-facing array of 4 panels thatâs heavily shaded in the morning and afternoon from trees on the east and south. I added 2 optimisers on the east and west panels, and it made a big difference.
They work by dropping the voltage of the string while allowing the string to run at maximum current. So before installing them, in the morning when the east panel was shaded and the other three were in full sun, Iâd get around 150V and 1.5â2A until that shaded panel finally lit up. All that energy was being forced through the bypass diodesânot great for panel longevity.
Now, with the optimisers, the system drops the voltage to about 120V, but the current jumps to 9.4A. Iâm only gaining around 1â2 kWh a day, but Iâm also saving the east and west panels from diode abuse, so itâs worth it.
Interesting. First time I am reading about optimisers. From your explanation though it sounds like the same thing that MPPTs do isnât it? They regulate voltage to give maximum current right via some efficiently curve I do not try to understand?
The sun suddenly seems to have dipped more aggressively towards the horizon in just the past couple of days, which I am wondering if that is just what is happening and coincidentally I was messing with the panels at the same time. I havenât had this string up long enough to know what averages to expect through the seasons.
I am in a south facing valley and it is 08.45AM and just went outside to look and only just seeing sun beams to start breaking over the hill to the west.
EDIT: Wow!!! Yea buddy! I just checked and at 09.05AM I am clocking 61V, 1.1A, on the strings resulting in 5.2A to the battery! This is with them set back to near vertical. Never seen that kind of output so early in the day that I recall. Hmm glad I persevered with vertical mounting for a little longer.
Sort of. The MPPT will try to drop the voltage of the entire string to find the maximum power point, where an optimiser will do it just for that one panel that is shaded. It sounds like you might have a problem. You can do a short circuit test and see if there is any current in the string, and then test a single panel.
Ahh check my edit as you posting while I was still editing. The MPPT reader was just playing up. I checked this by using my clamp meter on the wires and they were showing current. I reset the reader and actually getting amazing output for this time in the morning!
Up to 8A now! This is fantastic for early morning! Vertical in winter for the win! I guess it was just a lackluster solar day yesterday. I sometimes find that happens even if it looks relatively clear to the eyes.
If its easy to adjust, go perpendicular to sun for max output when suns out. For overcast days you may get better performance going full horizontal for maximum capture of the albedo.
