Oversizing Solar Panels

[burgerking]

This caught my attention on my Deye 5K inverter.

(Deye 5KW has 2 String Inputs, each with its own MPPT)

I have always thought that I could feed 3.5KW~5KW of PV power into a single string. In particular, I plan on oversizing my Solar Panels, to compensate for cloudy skies, to compensate for higher power draw in the afternoon and such.

I do not intend to pull more than 5KW out of this 5KW Deye Inverter.
Nor do I intend to charge my batteries at Deye's 120A max capacity.
I do however plan on adding and rearranging PVs such that my Deye would be able to start charging 60A~80A throughout the day (from 7AM to 5PM) and even 40A during cloudy days.

I do understand that components have maximum limits. Diodes and Transistors for instance will break if excessive current.
My question. Does Deye's MPPT circuit have limiter to prevent excessive power?
Should I rely on this? Or must I prevent it by limiting the PV itself?

PS. My current 16 Panels divided into 2 strings, can deliver only 3.5KW peak combined.
I plan on combining these into a single string (8 panels facing East, 8 Panels facing South), and then add another 6 pc of 500W panels all facing West.

 

[timselectric]

Over paneling is very common. Generally 25% to 50%.
Beyond that, it becomes not cost effective. The SCC will limit what it will pull from the panels.
VOC is a hard number, do not exceed that.

 

[ncsolarelectric]

You are correct. It will only draw as much power as it needs, the limit is false. However, some manufacturers do that and then void the warranty if you exceed it.

 

[MarkSolar]

Your inverter is allowing 30% over panelling which is pretty common. You are proposing over paneling by as much as 100% (10kW on a 5kW inverter). You might consider other options like buying 2 inverters, or a larger one. Being in the Phillipines it's hard to imagine why you would want to overpanel by even 30%.

 

[wattmatters]

You are correct. It will only draw as much power as it needs, the limit is false.

Most good inverter MPPTs will clip PV current at whatever their rating max is (a scenario which is more common with grid tied systems which can export and so pretty much always work to generate the maximum output they are capable of). I can't speak for Deye but I'd be surprised if it did not also have an upper current limit.

Here's an example from my grid tied inverter. It has two MPPTs but one has a higher current limit than the other:

Each MPPT has the same sized paralleled arrays but slightly different orientations. Can clearly see MPPT 2 clipping current during the middle of the day.

Your inverter is allowing 30% over panelling which is pretty common. You are proposing over paneling by as much as 100% (10kW on a 5kW inverter). You might consider other options like buying 2 inverters, or a larger one. Being in the Phillipines it's hard to imagine why you would want to overpanel by even 30%.

About 1/3rd more than the AC output rating is a pretty nice balance.

But I can imagine a doubling of PV array capacity (relative to AC output rating) would work OK with paralleled arrays facing significantly different orientations, such as East and West on a fairly steep pitch roof. Works a bit like having a single axis tracker without having a single axis tracker.

 

[burgerking]

Your inverter is allowing 30% over panelling which is pretty common. You are proposing over paneling by as much as 100% (10kW on a 5kW inverter). You might consider other options like buying 2 inverters, or a larger one. Being in the Phillipines it's hard to imagine why you would want to overpanel by even 30%.

I am not oversizing by 100%.
Like I said, my current 16 panels (2 strings) can only deliver 3500W and is slightly more than what a single MPPT port can handle (3250W).
Deye comes with 2 MPPTs. So I plan on adding another string just for that. So technically I am not oversized by a big margin.

My ultimate goal is for my old 16 panels to work morning (East red string), noon (South orange string). New panels to work in the afternoon (West green string) - (I have a flat roof top. I can rearrange them however I like.)

I am not sure if this will work. Will the East Panels receive same solar power as the Noon Panels during their corresponding time as suggested in the above chart? Will Red be actually lower indicative of what is called "sun-peak-hours"?

Below is Deye's MPPT specs, and the panels I wish to add (still deciding which one), either 465W x 8pcs or 545W x 6pcs.

 

[RSahan]

Hi @burgerking Do you have the SG03 model?

 

[burgerking]

Hi @burgerking Do you have the SG03 model?

yes

 

[chrisski]

I am not sure if this will work. Will the East Panels receive same solar power as the Noon Panels during their corresponding time as suggested in the above chart? Will Red be actually lower indicative of what is called "sun-peak-hours"?

In my signature block there is an off grid calculator where you can calculate overall output.

IME of setting up panels east facing for the morning, moving them to south for noon, and moving them west for sunset, the same panels make more peak power at noon. It’s got to do with angle of the sun. How much less is based off how high the sun is,

 

[Delphinus]

Like I said, my current 16 panels (2 strings) can only deliver 3500W and is slightly more than what a single MPPT port can handle (3250W).
Deye comes with 2 MPPTs. So I plan on adding another string just for that. So technically I am not oversized by a big margin.

Below is Deye's MPPT specs, and the panels I wish to add (still deciding which one), either 465W x 8pcs or 545W x 6pcs.

Did you solve your problem? I also have a Deye 5KW and 2 strings of 8 x 545W panels, in Philippines you must reach the 6500W without problems check your installation.

First I started with 8 in the string 1 and if I'm not mistaken I got close to 4KW in September, I have a record with 12.1A with a total 3652W.

During winter I install another identical string and now that we have more sun the inverter started to clip the current, I was planing to disconnect 2 panels in each string during summer, but looks that won't be necessary but I will test it since when charging the DC temp sensor gets over 60º C that is over 40ºC of ambient temperature and I have an fan helping cooling the cylindrical dissipater.

This mine at 6500 KW.