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Optimizers


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Hi Guys, I have 4 x solar PVs facing NE, about 75 deg East and another set of four facing SW, about 250 deg West. These panels are 405W JA Solar panels and so far, the maximum I canget out of the ones facing SW is 1200W and ones facing NE I can only get 980W. I have no other options of mounting the panels because of my roof and need to know if getting the Optimizers will help improve my situation. Please help

 

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1 hour ago, hoohloc said:

Hi Guys, I have 4 x solar PVs facing NE, about 75 deg East and another set of four facing SW, about 250 deg West. These panels are 405W JA Solar panels and so far, the maximum I canget out of the ones facing SW is 1200W and ones facing NE I can only get 980W. I have no other options of mounting the panels because of my roof and need to know if getting the Optimizers will help improve my situation. Please help

 

I have a program with which I can calculate what you can expect, but I need to know the angle (from horizontal) of your roof/panels.

Edited by Calvin
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The graph below is for panels at 250 degrees.  if you look at the line for September, you will see a maximum of about 72%, which is about 1150W.  Your 980W is 85% of that.

image.png.849ca46acbdd8f1701f15425d39a711f.png

 

The graph below is for the panels at 75 degrees.  In September you max out at about 88%, roughly 1400W. Your 1200W is also about 85% of that.

image.png.d358ca9ec449de81df072af777741b6b.png

Not sure what MPPT you are using, but generally I think that the numbers you are seeing are a bit low. 

How do you get your figures? Are all your panels on one MPPT?

 

image.png

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2 hours ago, Tariq said:

hi Calvin,

  can I ask you to do the same for me, i live in Cape Town and all my panels face due Northeast at 35 degrees from the horizontal.

thank you

No problem - see below. Done for 34S, 18E panels face 45 at 35.

image.png.71e4aec479dfb5b9ed0a71620bc79137.png

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1 hour ago, hoohloc said:

Yep, the power is too low and would like to increase that. Any advice? 

You already have a separate MPPT for each group, which means that optimisers may not help much.

Remember that my graph is the ideal number.

In practice, you need to reduce what you expect by losses in the SCC, and more importantly by the losses due to the panel being hot.  Most panels are produce their rated power at 25C - my panels on a sunny spring day like today are running at 56C, and loses 0.37% for every degree.  That is a loss of 11.5%!

So, your total performance of about 85% is not far off - perhaps 1 or 2% below what you may have hoped for.

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3 hours ago, Calvin said:

You already have a separate MPPT for each group, which means that optimisers may not help much.

Remember that my graph is the ideal number.

In practice, you need to reduce what you expect by losses in the SCC, and more importantly by the losses due to the panel being hot.  Most panels are produce their rated power at 25C - my panels on a sunny spring day like today are running at 56C, and loses 0.37% for every degree.  That is a loss of 11.5%!

So, your total performance of about 85% is not far off - perhaps 1 or 2% below what you may have hoped for.

Thanks for the info, much appreciated. It looks like I will have to install more panels to make up for the loss

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18 hours ago, hoohloc said:

It looks like I will have to install more panels to make up for the loss

Well still there is no explanation why these panels give less. Are they shaded? Your SW aray gives more power than the NE, that's weird. How are they connected? 4s per array?

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20 hours ago, RikH said:

Well still there is no explanation why these panels give less. Are they shaded? Your SW aray gives more power than the NE, that's weird. How are they connected? 4s per array?

They are not shaded, yep the SW arrays gives more power from 07:30 up to 14:30. after that the NE stays around 950w when the SW drops to lower power. They are connected in series parallel. I have two panels connected in series and then connect in parallel to another set of two series connected.  Yep 4 per array

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On 2020/09/08 at 7:27 PM, Calvin said:

I have a program with which I can calculate what you can expect, but I need to know the angle (from horizontal) of your roof/panels.

Hi Calvin, Can I ask that you do the calc for my installation. I have 16x405W CS panel north facing, all connected to a victron charge controller 250/100 and my roof angle is 26 degrees.

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12 hours ago, Muchachos said:

Hi Calvin, Can I ask that you do the calc for my installation. I have 16x405W CS panel north facing, all connected to a victron charge controller 250/100 and my roof angle is 26 degrees.

No problem, see below (all assuming Cape Town - let me know if you are somewhere else)

image.png.b12937b31364def335ec9fbd70400931.png

I saw you were considering moving 4 to the West: This is how it would look

image.png.4a43c5f640de97ebed022d3a7617f3f5.png

And finally, 8 North, 4 West, 4 East

image.png.2accf92dd7f8e6ce1e3d9a5ceeed4180.png

 

This last one is wrong, but the forum software does not allow me to delete it....

 

image.png

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10 hours ago, Muchachos said:

Sorry I didn’t mention this. I am in Pretoria.

No problem - adjusted to 26S 28E

All 16 North

image.png.f6cff2efbbf2659d1606268ffb83a599.png

4 West, 12 to North

image.png.ea2941554db48f992bc1c7a89f117921.png

 

4 to West, 4 to East, 8 to North

image.png.670d50db4b42d79ff8b03d7c4266941a.png

You need to be careful here: moving panels like this gives you more early and late, but in July total daily production decreases from 5.4kWh to 4.4kWh (per kW installed).  Given that most of us size our systems for winter, losing 20% in winter is not ideal...

Also note that these figures are for the case where each bank has it's own MPPT to optimise it's production.  If you combine different orientations on the same MPPT you will lose a lot more.

Summary: at our latitudes, having East/West panels gives you more power early and late in summer, at the expense of some midday power.  In mid-winter it gives you no extra power ever, and costs you 20% on average (with your 8/4/4).

To see how bad the East-West is in winter, here is a graph with all 8 East and 8 West.  You can see that July is now down to 3.4kWh/kW.

image.png.af48abb2600c233511658a9d12f9dd6a.png

Edited by Calvin
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Thanks Kelvin, this opens a new point of view from a thinking perspective.

 

I am considering adding 4 more panels to the systems and changing my configuration to 4 E, 12 N and 4 West.

This because adding more Noth panels means I need to buy and MPPT and I am not ready for that investments since I would prefer to add another 250/100 for future expansion.

 

What do the number looks like for my considered system?

 

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12/4/4 below

image.png.80c6af6d4d70fcf8f5ef9ae899b60a1d.png

 

Just to put it clearly: below is the numbers for North vs West vs East on 1 July in Pretoria (26 degrees panel angle)

image.png.8d31b4c09752127742a759bb5a20f7c0.png

As you can see the West and East facing panels are not bringing much to the party. Slight gains early / late, huge losses rest of the time.

 

 

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Thanks Calvin,

What optimizer do you recommend and do you know who has the best price in the market?

23 hours ago, Calvin said:

Also note that these figures are for the case where each bank has it's own MPPT to optimise it's production.  If you combine different orientations on the same MPPT you will lose a lot more.

So in order to get the best production of the current North facing installation with optimizers. I need to split the installation into two MPPTs at least, with each two parallels per MPPT?

My roof currently only has space for an additional 4 north facing panels, 6 east facing and 6 west facing. This is the reasoning for considering east and west facing panels. The ideal scenario would be a configuration that does not loose more than 5% of the current north facing peak whilst getting more morning and afternoon production.

My current total kWh production is kWh is between 34 and 40. The hope is that with the east and west total production should provide an additional 12kWh to get to a system total of around 50kWh on average. Which would produce about 30kWh on cloudy days and between 10 and 15kWh when it is raining.

What would be the most cost effective configuration for this?

 

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