Which direction should solar panels face?

[MJCM]

1 minute ago, Muhendis said:

I have seen a solar panel array with a few added panels facing east and west angled to catch the early morning and late afternoon sun. This in addition to the main array facing south. The east and west panels are a bit useless most of the day but maybe that arrangement will allow for good battery charging early and late so less main power needed the rest of the day.

That is my thought as well! Oke make it 2 East and 2 West (that is another 1300 Watts), then the question for me remains what about the Inverter? Do I need to up-size it??

[Muhendis]

9 minutes ago, MJCM said:

Does this mean I have to get a BIGGER Inverter as well (> 5kW ???). ?

The size of the inverter is dependant on the load. You need to consider the charge controller maximum power input. However if the charge controller is an integral part of the inverter the the answer is possibly yes.

Bare in mind that the power in the morning will mainly come from the side so the main array will not have such a great output. The daily average power may not exceed the charge controller input.

[Bandersnatch]

5 minutes ago, jaideedave said:

What about at night..?

 

Then you will need a Dual Axis Luna Tracker 

 

 

[Raphael Hythlodaeus]

1 hour ago, Skeptic7 said:

Up

I disagree Skeptic - should be face Down to protect the panels from UV radiation.

[JBChiangRai]

7 minutes ago, Raphael Hythlodaeus said:

I disagree Skeptic - should be face Down to protect the panels from UV radiation.

I put mine in the shade for that.

[MJCM]

16 minutes ago, Muhendis said:

The size of the inverter is dependant on the load. You need to consider the charge controller maximum power input. However if the charge controller is an integral part of the inverter the the answer is possibly yes.

Bare in mind that the power in the morning will mainly come from the side so the main array will not have such a great output. The daily average power may not exceed the charge controller input.

Thx @Muhendis

 

Email to the Installer for the Quote has been adjusted/amended !!

 

I am now thinking a total (if 330w) of 19 Panels.

 

2 > E

2 > W

15 > S

 

[Rimmer]

All my panels face due south, they all get a full charge and work well. The golf club near me has a giant solar light and the panel is angled north, that seems to come on and go off as it should as well

[Muhendis]

Here is a thread I wrote some time ago which you may find helpful:

 

I have recently needed to carry out some repairs to one of my combiner boxes due to a faulty diode. At the same time I decided to review my setup which has morphed a bit over the years. No conflicts were discovered and all is still working optimally but the thought occurred to me to pass on my system matching knowledge to all. 

 

Starting at the solar panel end.

 

Firstly, the voltage output of the strings of solar panels must never exceed the charge controller input maximum voltage limit.

 

Secondly, the working voltage output of the strings needs to be within the range of the charge controllers MPPT range.

 

The label on the back of the solar panel includes a Pmax number in Watts. This is the maximum power the panel can give under direct, perpendicular to the panel (1Kw/M²), sunlight and at 25ºC. If you add all the panel's Pmax together this should be less than the manufacturers data for the maximum input power of the charge controller.

 

The reason for this limit is to restrict the current flow to below what the charge controller can handle when charging batteries. The batteries will take all they can get and more and the charge controller does not have the means to limit it. That's MPPT for you. The limiting factor is how much current the panels can deliver. A simple calculation reveal's all. If you have 6.4kw of panels and a 48v battery then applying Ohms Law the maximum current will be 6400 ÷ 48 = 133.33 Amps.

 

The charge controller must be able to pass this amount of current. However, in other posts it is noted that the solar panel outputs in Thailand will be somewhat less due to temperature derating. By assuming a very conservative 10% panel output derating the sum changes to 5760 ÷ 48 = 120Amps. From this, a charge controller capable of 120Amps output will fine. I use two at 60Amps each.

 

The capacity of the battery needs to be great enough that the maximum current does not exceed the maximum charge current rate. If the battery capacity is greater then they will simply take longer to fully charge so the batteries need to be sized according to the planned depth of discharge for the load.

 

In the case of my installation I targeted 30% depth of discharge which gives me full batteries by lunchtime'ish. The example of the total power of the panels and the charge controllers is from my own installation and  I have a 750Ah 48v Gell battery assembly.

[MJCM]

2 hours ago, MJCM said:

We already have that for our 3 Panels. When I walk over there I will take some pictures.

 

My BIL made it together with his son, the total construction incl the 6 concrete poles (where the structure rests on) was something like 4000 THB. (excl the panels)

 

Here a picture from the distance (will post other pictures later)

 

 

 

Here the more detailed pictures of the structure to angle the panels!! Works great but needs 2 people to operate!

 

 

 

[NoshowJones]

19 hours ago, MJCM said:

You forgot SWMBO ????

There is a thread about swimming pools further back. ????

[AgMech Cowboy]

21 hours ago, FritsSikkink said:

They should face the sun.

That's what I was going to say. You get the worm early bird.

[MJCM]

2 hours ago, Muhendis said:

The size of the inverter is dependant on the load. You need to consider the charge controller maximum power input. However if the charge controller is an integral part of the inverter the the answer is possibly yes.

Bare in mind that the power in the morning will mainly come from the side so the main array will not have such a great output. The daily average power may not exceed the charge controller input.

As I intend to get a Growatt inverter I was looking up the specs of them and looking at them and their MAX recommended PV Power it ranges from 6600 W (for the 3kW one) up to 8000 W (for the 4999 W one)

 

Would this suffice? (Thus only need 1 Inverter for my 19 panels (330W each) ?)

 

[007 RED]

Seems that there are a few different opinions as to which direction solar panels should be facing in order to acquire maximum sunlight for your solar panels.

 

When I was doing my research into my proposed GTI system (during the Covid-19 self hibernation) I found a number of charts that show the sun's path throughout the year but unfortunately none were specific to Thailand.  Quite by chance I stumbled across this website http://andrewmarsh.com/apps/staging/sunpath3d.html which gives a wonderful 360⁰ 3D view of the sun's path and the shadows it can produce.  The real bonus being that you can enter your lat/long co-ordinates and time and it will produce the 3D display specifically for your location.

 

Not over keen on the buildings that they use, but it does give you a very good indication as to where shadows will form.

 

By moving the date slider you can see the sun's affect throughout the year.

 

To enter you co-ordinates go to the 'Globe' icon on the right of the menu bar.  Date and time are set via the 'Calendar' icon on the right of the menu bar.  If you want the map to display your location, pull down the 'Pin' icon on the left menu bar and I selected "ESIR Street Map".

 

Have fun ????

[Muhendis]

34 minutes ago, MJCM said:

As I intend to get a Growatt inverter I was looking up the specs of them and looking at them and their MAX recommended PV Power it ranges from 6600 W (for the 3kW one) up to 8000 W (for the 4999 W one)

 

Would this suffice? (Thus only need 1 Inverter for my 19 panels (330W each) ?)

 

Looks good to me. Don't forget the temperature de-rating of the panels. As the temperature goes up their output gets less. In Thailand you should be able to allow an additional 10% for the panel output due to heat losses. So on a hot sunny day your 6270W will probably be more like 5643W but only when the sun is shinning perpendicular to the panel. Other times you would expect even less.

[Muhendis]

3 minutes ago, 007 RED said:

Not over keen on the buildings that they use, but it does give you a very good indication as to where shadows will form.

I use Trimble Sketchup (used to be Google Sketchup) for that. You can draw your own buildings just like real life.

[motdaeng]

i made a comparison, but i'm not sure how accurate this (german) tool is! 

location bangkok / slop 10˚ / 10 kwp

south orientation 13'046 kwh = 100 %
west orientation  12'551 kwh =  96.2 %

so the different south to west  orientation seems to be only 3.8  %! 

[MJCM]

3 hours ago, Muhendis said:

Looks good to me. Don't forget the temperature de-rating of the panels. As the temperature goes up their output gets less. In Thailand you should be able to allow an additional 10% for the panel output due to heat losses. So on a hot sunny day your 6270W will probably be more like 5643W but only when the sun is shinning perpendicular to the panel. Other times you would expect even less.

THX!!!!!!!!!!!!!!

 

So am I correct in thinking that you could even go higher (in total Solar Panels) and not even touch the Max Recommend PV Power your Inverter is rated at because of this? (up to a certain point that is ???? )

 

And second thing from your post, it also depends on your location and if (for example Northern Hemisphere) with colder temperatures you will get more PV yield if you use (for example) the same amount of panels in Norway then in Thailand? (if you angle them correctly)

 

So the HEAT in Thailand is not a good thing for Solar panels but the abundance of Sunshine is!!

 

Thx @Bandersnatch for this thread a real eye opener for me and @Muhendis for the patience in answering my NooB questions and teaching me!

[Bandersnatch]

32 minutes ago, MJCM said:

And second thing from your post, it also depends on your location and if (for example Northern Hemisphere) with colder temperatures you will get more PV yield if you use (for example) the same amount of panels in Norway then in Thailand? (if you angle them correctly)

 

So the HEAT in Thailand is not a good thing for Solar panels but the abundance of Sunshine is!!

The reason I chose 7am, 21st Dec, the winter solstice for my video was to demonstrate the tremendous advantage we have here in Thailand for solar production.

 

Sure we suffer a little loss of efficiency due to heat, but that is far less of a factor compared to the fact the sun didn't rise in Oslo until 09:18 on 21 December 2021. As the temperature at the time was -8 degrees C, you probably had to clear the snow off the panels first.

 

[MJCM]

6 minutes ago, Bandersnatch said:

The reason I chose 7am, 21st Dec, the winter solstice for my video was to demonstrate the tremendous advantage we have here in Thailand for solar production.

 

Sure we suffer a little loss of efficiency due to heat, but that is far less of a factor compared to the fact the sun didn't rise in Oslo until 09:18 on 21 December 2021. As the temperature at the time was -8 degrees C, you probably had to clear the snow off the panels first.

 

 

Thanks @Bandersnatch to point that out, so my last remark in that post isn't far off ????

 

50 minutes ago, MJCM said:

So the HEAT in Thailand is not a good thing for Solar panels but the abundance of Sunshine is!!

 

[Muhendis]

45 minutes ago, MJCM said:

So am I correct in thinking that you could even go higher (in total Solar Panels) and not even touch the Max Recommend PV Power your Inverter is rated at because of this? (up to a certain point that is ???? )

Yes up to a point as you say. Panels are tested in a chamber with ambient air at 25ºC and a draught blowing across them. I can't remember the wind speed. a calibrated sunlight source is shone on them equivalent to 1kW/M². The output of the panel is measured and the label printed and stuck on the back. each panel is tested and grouped ±5Watts I think. In Thailand that test temperature is generally exceeded especially at midday so output will be down.

56 minutes ago, MJCM said:

And second thing from your post, it also depends on your location and if (for example Northern Hemisphere) with colder temperatures you will get more PV yield if you use (for example) the same amount of panels in Norway then in Thailand? (if you angle them correctly)

Yes but the days are shorter so......

 

57 minutes ago, MJCM said:

So the HEAT in Thailand is not a good thing for Solar panels but the abundance of Sunshine is!!

Yes

[MJCM]

= post withdrawn =

[Muhendis]

One further point about solar panels is that they slowly loose their ability to produce electricity. After 20 years they will be producing about 80% of their original electricity output.

[Muhendis]

Just now, MJCM said:

Not in their Summer they aren't (up to 24hrs of daylight ???? )

Yes I forgot that. even in Stockholm the sun goes to bed at something like 2 a.m. and up again by 4 a.m. in summer.

I don't want to talk about winter.

[MJCM]

6 minutes ago, Muhendis said:

Yes I forgot that. even in Stockholm the sun goes to bed at something like 2 a.m. and up again by 4 a.m. in summer.

I don't want to talk about winter.

I removed that post because it wasn't fair to say that IMHO, because in the Winter there are regions which even don't get sunlight (or only maybe 1-2 hours).

 

But your point is very clear, Cold weather is better for Panels but in Northern Hemisphere (colder weather) you have less sunshine

 

[davidkas]

Thank you all for an interesting topic.

I am planning to go solar later this year, I don't plan to be off grid, I do plan to feed back to the grid when there is surplus. I know you don't get much for it but better than loosing all the peak output after the batteries are charged.

The problem is fining a reliable, trustworthy installer who will actually listen to my requirements and suggestions. Are any of you willing to give names of companies that you have had a good experience with?

Another thing I haven't seen mentioned in any detail on any of the forums is floating the panels on ponds. This seems a particularly good option for me and so easy to orientate the panels in any direction. Also the water reduces the heat loss and the panels provide shade for fish win win.

Any thoughts?

[Dazinoz]

1 hour ago, MJCM said:

So the HEAT in Thailand is not a good thing for Solar panels but the abundance of Sunshine is!!

Panels are rated at 25C. On the specification sheet you will see a negative figure and that is what the panel drops by each degree above 25 assuming same amount light. They work on light not heat from the sun. Many people think a hot climate is good for solar, its not. A cool sunny climate is.

[BrianStar]

Ideally, the panels should face 15.87­° (latitude of Thailand) South if you're trying to maximize your average power output throughout the year. If you needed more power during different times of the year, you may want to consider deviating from this. For example, Thailand is hotter when the sun is directly above (Late April/Early May) and so you may need more air conditioning power at that time and would have your highest power output at that time if your panels face directly up at 0°. The consequence is you'd have less power available during the "winter" due to the sun's incident angle being as high as 39.37° around Dec 21st but if air conditioning is your primary cost, this trade-off might work.

 

The roof facing East and West is an issue I have. Putting panels on the East and West side of the roof to cover morning and evening would not be the most efficient. Ideally, you would use brackets to level the panels out and face straight up (countering the roof pitch) and then tilting 15.87° South for the best average output, and you should avoid the ends of the roof to avoid shading of the panels during the start of sunrise or end of sunset. There isn't a lot of power to capture during these high sun angles anyway, so it's not something to get too crazy about. And it may be easier to just go with more panels flush to the roof than to deal with trying to install them in a way that would counter the slope of the roof. So if you have the roof space, it's probably best to just do more panels.

[Dazinoz]

1 hour ago, BrianStar said:

 

Ideally, the panels should face 15.87­° (latitude of Thailand) South

 

Thais is not entirely correct. 15.87 is only one location in Thailand and not all of Thailand.

 

 From Wikipedia:-

 

What is the latitudinal extent of Thailand?

 

Kingdom of Thailand has a latitudinal extent of 5°37′N to 20°37′N and a longitudinal coverage of 97°22′E to 105°37′ E.

 

In the northern hemisphere panels should face due south at an angle of the latitude where they are being installed. A 30 second look up on Google.

[BrianStar]

Correct. I was quoting based on my exact location mostly as an example but failed to state that explicitly.

[KannikaP]

On 12/29/2021 at 4:39 PM, Crossy said:

 

ESS = Energy Storage System (battery)

kWh = Kilowatt hour (or unit on your power bill)

kWP = kilowatt photovoltaic (talking abour solar panels)

MPPT = Maximum Power Point Tracking - talking about solar charge controllers

PEA = Provincial Electricity Authority

 

Maybe we do need an abbreviations and acronyms thread.

Good idea. I hate these TLAs.