How to best utilize MPPTs

[Tigersun411]

Between my two inverters I have 8 MPPTs. All 45 panels are on the same roof plane. Is there any advantage in respect to shading to use all 8 MPPTs. I do have some trees that will shade different areas of the array at different times of the day. Thanks
I attached a picture of my current SLD

 

[Tigersun411]

MPPT finds the best power based on amperage and voltage for a particular string of panels.

 

[sunsurfer]

Between my two inverters I have 8 MPPTs. All 45 panels are on the same roof plane. Is there any advantage in respect to shading to use all 8 MPPTs. I do have some trees that will shade different areas of the array at different times of the day. Thanks
I attached a picture of my current SLD

There is an advantage for shading for sure. Also, you gain some redundancy. I also like running lower voltage/power strings. I use multiple MPPT. My main system has 7 (victron)

 

[Tigersun411]

There is an advantage for shading for sure. Also, you gain some redundancy. I also like running lower voltage/power strings. I use multiple MPPT. My main system has 7

Thanks. That was my line of thinking. What size system do you have?

 

[chrisski]

Between my two inverters I have 8 MPPTs. All 45 panels are on the same roof plane. Is there any advantage in respect to shading to use all 8 MPPTs. I do have some trees that will shade different areas of the array at different times of the day. Thanks
I attached a picture of my current SLD

OP has an inverter with 4 built in MPPTs. Disregard comments below which are built for buying MPPTs for an inverter that does not have them.
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You show 32 panels grouped in 4s. You say you have 45 panels. Provided it’s 32 as in the diagram:

With that setup any of those could be put in parallel onto two or three SCCs, depending on the panels and SCCs.

There is no extra power is produced or lost by getting multiple SCCs. With a single SCC and multiple parallel strings, the shaded panel just does not contribute as much in the sun.

The sum of the 8 different strings will be the same whether they are run through one or 8 SCCs.

 

[Tigersun411]

You show 32 panels grouped in 4s. You say you have 45 panels. Provided it’s 32 as in the diagram:

With that setup any of those could be put in parallel onto two or three SCCs, depending on the panels and SCCs.

There is no extra power is produced or lost by getting multiple SCCs. With a single SCC and multiple parallel strings, the shaded panel just does not contribute as much in the sun.

The sum of the 8 different strings will be the same whether they are run through one or 8 SCCs.

Most are in groups of six there are a few groups of five. There's a better image where you can read the panel count. Not familiar with SCC's

 

[chrisski]

Most are in groups of six there are a few groups of five. There's a better image where you can read the panel count. Not familiar with SCC's

The inverter has 4 MPPTs built into it. Deleted comments below.
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[sunsurfer]

Thanks. That was my line of thinking. What size system do you have?

I have two system, one is 2.8kw(12v) with 7x 30amp victron SCCs. The other is a 4kw (24v) with 5x Victron SCCs. I'm adding 2 48v systems very soon.

 

[SamDeleted]

@Tigersun411 to answer your question, YES , splitting your panels over separate MPPTs will help with shading , especially uneven shading (eg. Full sun one half of array, shade the other)

string panels together that get shade at the same time... If had 2 MPPTs, I'd go left side/right side

You also need to make sure you have enough panels in each string (series) to meet your MPPTs minimum 'start up' voltage

Not familiar with SCC's

SCC, solar charge controller ?

 

[Tigersun411]

Incorrect. Try again?

Thanks for you help!

 

[Tigersun411]

@Tigersun411 to answer your question, YES , splitting your panels over separate MPPTs will help with shading , especially uneven shading (eg. Full sun one half of array, shade the other)

string panels together that get shade at the same time... If had 2 MPPTs, I'd go left side/right side

You also need to make sure you have enough panels in each string (series) to meet your MPPTs minimum 'start up' voltage





SCC, solar charge controller ?

Thanks I appreciate the answer. My Goodwe inverter start up voltage is 150v and I am using Canadian solar 400w panels which have a nmot of 28.8v. Also the MPPTs operating voltage is 80-550.

 

[SamDeleted]

My Goodwe inverter start up voltage is 150v and I am using Canadian solar 400w panels which have a nmot of 28.8v. Also the MPPTs operating voltage is 80-550.

Mmm , is it 150v start up , or is it 80v minimum?


You'd need at least 6 panels in series to get over that 150v start up

don't forget solar panel voltage changes based on temperature, colder it gets the higher the voltage

Solar Panel Maximum Voltage Calculator - Footprint Hero

Calculate the maximum open circuit voltage of your solar array. Find your max solar panel voltage to correctly size your solar charge controller.

footprinthero.com

 

[Tigersun411]

Mmm , is it 150v start up , or is it 80v minimum?


You'd need at least 6 panels in series to get over that 150v start up

don't forget solar panel voltage changes based on temperature, colder it gets the higher the voltage

Solar Panel Maximum Voltage Calculator - Footprint Hero

Calculate the maximum open circuit voltage of your solar array. Find your max solar panel voltage to correctly size your solar charge controller.

footprinthero.com

I think that's for the entire inverter. I have four MPPTs they should add up to well above the minimum voltage unless I'm understanding it incorrectly

 

[chrisski]

Thanks I appreciate the answer. My Goodwe inverter start up voltage is 150v and I am using Canadian solar 400w panels which have a nmot of 28.8v. Also the MPPTs operating voltage is 80-550.

NMOT is nominal operating temperature.

28.8 volts is pretty low for a 400 watt panel. I’d expect in the 40 volt range for since most panels are built to max out at around 10 amps.
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I’m also going to edit my comments above since I see that this inverter seems to have a MPPT built in.

 

[Tigersun411]

NMOT is nominal operating temperature.

28.8 volts is pretty low for a 400 watt panel. I’d expect in the 40 volt range for since most panels are built to max out at around 10 amps.
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I’m also going to edit my comments above since I see that this inverter seems to have a MPPT built in.

Here's the solar panel data sheet

 

[SamDeleted]

Here's the solar panel data sheet

400w

Vmp 30.8v
Voc 36.8v


These are the important figures

 

[SamDeleted]

I think that's for the entire inverter. I have four MPPTs they should add up to well above the minimum voltage unless I'm understanding it incorrectly

I think you are miss understanding it , but saying that I don't quite understand it myself ?

 

[Tigersun411]

I think you are miss understanding it , but saying that I don't quite understand it myself ?

Sure standard test conditions but I still think my voltages are good for the entire inverter to start up. Hopefully somebody will correct me if I'm wrong and my solar planning people aren't setting me up for failure

 

[chrisski]

400w

Vmp 30.8v
Voc 36.8v


These are the important figures

Thank you I can’t download and open the OPs attached file. Right now all voltages of the 5S panels and 6S panels are more than 150 volts.

The 5S panels would actually be less on a hot day.

 

[SamDeleted]

Thank you I can’t download and open the OPs attached file. Right now all voltages of the 5S panels and 6S panels are more than 150 volts.

The 5S panels would actually be less on a hot day.

Do you think 6s minimum to meet that 150v then ?