Has really no one ever tested to get power from sunrise till sunset ?

[GoetzSaCebu]

Ok 1st thing I live in the philippines and sunrise here is 6am and sunset 6pm (to make it easier).
I installed my system 8x 500W panels now facing sunrise and I see that from 7am it already generates 0.5KWh until 3pm when the roof is in the shade and production drops.

What I want to change is that 4 panels face sunrise and 4 panels face sunset - so that I get more power even in the hotter afternoon!

But my installer tells me that its a bad idea, because the lower generation of the panels facing the shadow side will lower overall power that the inverter will generate (DEYE 5KW hybrid with 2 seperate PV inputs).

I asked DEYE and their answer was:
"Hello, your idea is right, 1.5 kw + 0.4 kw = 1.9 kw, but I suggest that solar panels should be mounted on the strongest side of the sun so that the energy output is maximized."

Somaybe someone here can answer me this:
Given 4 panels facing sunrise - generating 2KWh and 4 panels facing sunset generating 0,5KWh only.
I should still get 2,5KWh usable poewer, and not only maybe 1KWh because the inverter somehow limits what he can use by the input from the weaker channel.

And NO I wont install a suntracker system because my roofs are already pointing in the directions I need.

As my installer still thinks its no good idea to what I think of I now want to know from your experience if (especially DEYE inverters) maybe have a stranger behaviour than what I would say are regular inverters that would just add up the power they get.

 

[sunshine_eggo]

A south facing fixed array at the proper tilt will generate the most energy. Period.

From:

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations

pvwatts.nrel.gov

Data for Manilla:

South facing:


Split (2kW East):


2kW West:



4kW Array facing 180°, 14° tilt: 5175kWh/year
4kW Array split, 2kW 90°, 14° tilt + 2kW 270° 14° tilt: 5000kWh/year

That's about 3% less.

A steeper tilt would harvest more in the earlier hours and more in the later hours at the cost of total and mid-day:

Split: 2kW 90° @ 45° tilt + 2kW 270° @ 45° tilt: 4391kWh/year - about 15% less than a south facing array.

You can answer your own question by using the website I linked above. You can download HOURLY data for various scenarios and see what your production would be throughout the day. You would model each array separately, download the hourly CSV data and then manually combine them into a single sheet to see your results. This is a tool that will allow you to conclusive establish an array's performance - not what you or the installer thinks is best. Invest an hour modeling the scenarios I provided, and you can compare their performance.

Consider that the only time you're going to get maximum output is at high noon with the panel perfectly perpendicular to the sun. Sunrise/Sunset have much less energy to offer since the light has to pass through more atmosphere, so even if you have the panels perfectly perpendicular to the 7am sun, you're going to get far less than the maximum you'll get at noon.

 

[GoetzSaCebu]

Your answer is only shows that you have no geographie knowledge at all and don't understand what sunrise and sunset near the equator mean. As a small hint for you - at noon time the sun is 90 degrees above my head!

 

[sunshine_eggo]

I understand it completely, and I provided you with the tools to use to actually calculate the difference between the two scenarios and eliminate any question of which is better for your situation.

Please consider the possibility that your assumptions may be incorrect.

I suspect you don't understand the numbers I used.

90° means East facing.
180° means South facing.
270° means West facing.

14° and 45° means the tilt angle from horizontal.

 

[GoetzSaCebu]

Ok let me ask this different

If my DEYE hybrid inverter has 2 PV inputs and I feed 200V 100A into PV1 but only 160V 3A into PV2 - what will be the overall usable energy ?

2000W + 480W = 2480W or will PV2 limit somehow PV1 and the usable power will be less than 1KW?

My installer tells me that the latter is the case.
So I like to find out if he is correct and what magic then happens in the DEYE Inverter (or any inverter?)

 

[sunshine_eggo]

200V @ 100A would be 20,000W. I doubt the Deye supports that.

I don't have any data on the DEYE unit specifically, but it seems to be a common requirement that if there are two MPPT in an AiO unit, they should have about the same power on them.

Have you consulted the manual or contacted DEYE?

 

[sunshine_eggo]

https://www.deyeinverter.com/deyeinverter/2021/12/22/【b】30240301000353-502012729-使用说明书-组串单相-sun-(3.6-6)k-g-德业英文-封面彩印-封面封底157g-内页70g铜版纸-142.5×210mm-g04.pdf

See 7.4

 

[GoetzSaCebu]

Like always in life the manual does say exactly 0 to that szenario and I doubt any other inverter manual will tell.
And I also doubt that ANY Youtuber - not even our beloved Will has ever tested that with different inverters.
As always I fear I am the first to ask this question ...

 

[Don B. Cilly]

I understand it completely

Well, completely completely... there isn't a place called "Manilla", is there?
Manilla means "handle" in Spanish BTW - very widely spoken in the Philippines.

Still, he could try with two panels SE, two S, two SW.
-

 

[GoetzSaCebu]

Like in this video Why South is Not Always the Best Orientation for Solar Panels - YouTube my panels at the moment face east.
I generate enough energy to run my aircons AND charge my 10KWh battery.
But after 3pm the panels are in the shade and the battery has to power the appliances.

The problem is only that afternoon is the hotter time of day and the aircons need more power. But only the battery is used then.

Instead of now having all 8 panels facing east I would like to have 4 panels east and 4 panels west - so that even after 3pm I still get 1KW+ because the sun still shines until 6pm.
But my installer insists that its a very bad idea to have 4 east and 4 west facing panels as this lowers the usable energy in total.

 

[Hedges]

With two separate MPPT inputs, no problem that each gets different PV voltage. At least in most cases; it is possible two MPPT within a hybrid are linked in a matter which affects that.

You may be able to make each input same voltage, same number of PV panels in series. I don't have all your array details or inverter specs, but for instance 12 panels 4s3p facing East into one MPPT, and 4s facing West into one MPPT. Even different times of day, not that much different in voltage.
You could also put 4s facing West in parallel with 4s facing East into one MPPT, and 4s2p into other MPPT. Even connected in parallel, equal length strings of different orientation do not pull each other down, even if one is in the shade. Reason is, Voc in the shade is about same as Vmp in direct sun.

Facing Noon sun does make the most Wh per day. But, it might exceed maximum SCC or battery can take (less likely with just 8 panels.) It also might fully recharge battery then curtail production, followed by loads draining battery in the evening. For this reason, half facing West and half facing East might be better for a system with small battery, large array.

I generate enough energy to run my aircons AND charge my 10KWh battery.
But after 3pm the panels are in the shade and the battery has to power the appliances.

Exactly.

But my installer insists that its a very bad idea to have 4 east and 4 west facing panels as this lowers the usable energy in total.

Probably what he was taught, not what he actually understands in detail.


You have 4kW of panels, 10 kW of battery. Obviously just 2.5 hours full sun to completely recharge. Depending on night time loads, you'd like to have battery fully charged near sundown, and have PV panels produce power in excess of loads all day long.

 

[sunshine_eggo]

Like in this video Why South is Not Always the Best Orientation for Solar Panels - YouTube my panels at the moment face east.
I generate enough energy to run my aircons AND charge my 10KWh battery.
But after 3pm the panels are in the shade and the battery has to power the appliances.

The problem is only that afternoon is the hotter time of day and the aircons need more power. But only the battery is used then.

Instead of now having all 8 panels facing east I would like to have 4 panels east and 4 panels west - so that even after 3pm I still get 1KW+ because the sun still shines until 6pm.
But my installer insists that its a very bad idea to have 4 east and 4 west facing panels as this lowers the usable energy in total.

DEYE MPPT restrictions or lack thereof notwithstanding, shaded panels perform horribly. Getting 1kW out of 2kW of shaded panels is optimistic in the extreme. I expect that you would significantly reduce your morning collection and get very little after 3pm.

@the_colorist knows DEYE intimately. Hopefully, he can comment if he's still on the site.

 

[Sky-HHI]

Interesting video, as always your situation depends on your location and your demands. You could try having half the panels facing east and half facing west then you can compare the results. If you could move half the panels to the west roof temporally to test your idea , that may give you the answers you are looking for. Stay Charged.

 

[Phil.g00]

I have more than enough power at noon.
My objective is not to have more power, but more useable power throughout a longer day.
Auxilliary equipment needs to be sized for the peak, I try to attain a lower peak but more kilowatts throughout a longer solar day.
I do this by paralleling East and West arrays on the same MPPT, This gives me a very flat curve that starts early and finishes late.
It is very successful and I can use far more panels than a straight North array. So I get more power and more useable power not per panel but per MPPT.
But I want even earlier and even later.
I want to be off batteries and on sunshine as long as possible.
So I have been toying with the idea of vertical bi-facial panels.
In fact, I have even some technical calculations done, because there is a bi-faciality factor involved. In other words, one side is better than the other.
The theoretical calculation showed that at 30 degrees (S) latitude, if you off set the panels exactly North-West, the morning and evening peaks will be the same at the summer solstice.

 

[GoetzSaCebu]

My system is in my video here Finished installing our Solar plant. And it works GREAT! - YouTube
8x 500W panels TrinaSolar.

Todays generation was 21.4KW on a nearly cloud free day.
Sunrise was 5:42am and at 7:30am we hit the 1.4KW mark and stayed above that until 3pm.
So on sunny days I get 8 hours of energy that can run our house and and charge the battery.
Only after noontime we need 1 to 1.5 or sometimes 2KW because the aircons need more power during the hot afternoon.
At the moment all generation happens in the morning, so I wonder if it wouldnt make sense installing 4 more panels pls a battery facing the sunset and gaining from more solar time, instead also just sunrise side.

 

[Hedges]

But after 3pm the panels are in the shade and the battery has to power the appliances.

The problem is only that afternoon is the hotter time of day and the aircons need more power. But only the battery is used then.

Instead of now having all 8 panels facing east I would like to have 4 panels east and 4 panels west - so that even after 3pm I still get 1KW+ because the sun still shines until 6pm.

Getting 1kW out of 2kW of shaded panels is optimistic in the extreme. I expect that you would significantly reduce your morning collection and get very little after 3pm.

Are the 8 panels which face East in the shade after 3pm because trees cast shadows on them? If so, having them face West won't help, unless relocated to a different place without shade.

Or, are they shaded after 3pm because they are tilted away from the sun? And moving half from the East slope of your roof to the West slope of the roof, they will be in full sun? If so, should work great.

But where did "1kW+" come from? Half your panels is 2kW (STC). In full sun, would deliver 1kW+ for several hours. In shade, as Sunshine said, much less. Partial shade (falling on some panels) you may get the unshaded portion's wattage, depending on some things, especially minimum MPPT voltage of your SCC.

 

[stienman]

There are several ways to optimize your panel configuration, and your suggestion will accomplish your goal, so far as I understand it:

Facing one set of panels east and one set west will reduce your daily total solar power production, but will increase the time you are producing power. So rather than one sinusoidal hump which peaks at noon, you'd get two humps overlaid, the distance between the peaks defined by the difference in angle between the two arrays.

If you have sufficient battery storage, then you should optimize for total power produced, not more hours, but if your battery storage isn't sufficient then producing power when you need it is better than producing the most power possible.

Your inverter has two PV inputs, but it's not clear to me whether it has two MPPT chargers. If it does, then you're all set - go ahead and put the panels up as you desire, connect the east array to one MPPT input, the other array to the second MPPT input.

If your inverter has two PV inputs but only one MPPT, then you should purchase a separate MPPT for the second array.

 

[Hedges]

So I have been toying with the idea of vertical bi-facial panels.
In fact, I have even some technical calculations done, because there is a bi-faciality factor involved. In other words, one side is better than the other.
The theoretical calculation showed that at 30 degrees (S) latitude, if you off set the panels exactly North-West, the morning and evening peaks will be the same.

My thought on panel tilt is that up to about 45 degrees, most of its productive angle still gets sun. If tilted 60 degrees, so back-to-back with another panel, one facing East and one facing West for an equilateral triangle, an excessive amount is being missed when sun is below horizon.

I suggest no more than about 45 degrees, but have a reflective surface so more light from behind hits backside.
That is if area is no concern. More panels with front facing sun would give more power per unit area.

 

[stienman]

And I'm in the process of setting up nearly 4kw in the same way. 6 panels facing east, 6 west, with my existing 12 facing south.

 

[Phil.g00]

My thought on panel tilt is that up to about 45 degrees, most of its productive angle still gets sun. If tilted 60 degrees, so back-to-back with another panel, one facing East and one facing West for an equilateral triangle, an excessive amount is being missed when sun is below horizon.

I suggest no more than about 45 degrees, but have a reflective surface so more light from behind hits backside.
That is if area is no concern. More panels with front facing sun would give more power per unit area.

I would have other arrays as well, which would be far more productive.
The vertical panels would be part of a mix, ... aesthetic fencing if you will, and a completely enjoyable experiment to capture the earliest and latest watt.