solar panel serial or parallel?

mahdi89

New Member
Hi
I bought deye 5kw hybrid(SUN-5K-SG01/03LP1-EU)
-15 solar panel (trina 450w 11A 41v)
-300A 48v lifepo4 battery(15000kw)
Please may i know how to connect them?
In series or in parallel? What is the best diagram for me? Please help
Inverter pdf sheet attached
 

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wattmatters

Solar Addict
You have 15 panels (41V / 11A) and 2 MPPT inputs each with Voc limit of 500V and an 11A capacity it seems. You won't be putting such panels in parallel with an 11A MPPT capacity limit.

Easiest is just split the panels into two groups, each with a similar number of panels, e.g. 7 and 8, or 6 and 9.

Each group of panels is then put into series and connected to its own MPPT input.

Configuration is not just dependent on the electrical connection though, it depends on the physical space you have available upon which to mount panels and whether you wish to align arrays in different directions and or tilts to emphasise production at different times of day or times of year.
 

FilterGuy

What, me worry?
The key specs for the in inverter are these:
1631571156099.png

However, some of the specs are unfamiliar or a bit confusing to me:
* What is the Full Load DC Voltage range vs the MPPT Range?
* What does "No. of Strings per MPPT tracker" mean?
* Does the 11A rating of the PV Input Current mean that is the most it will draw or will there be damage if it is allowed to draw more than that.
(Most MPPT units will only draw a certain amount and won't draw any more).
* The PV input voltage is 370V(100V-500V) What does that mean. What happens if the voltage is between 425 and 500?

Note for this analysis I will assume the range should be between the 150V start up voltage and the 425V top of the MPPT Range. (This is a conservative assumption)

Having said that we can go a long way in answering your questions anyway.
I *think* these are the specs for your panels:
1631571696134.png
Right off the bat I see a couple of things.
1) Since the start voltage of the inverter is 150 volts and the open circuit voltage is 49.6 V, you will have to have a Minimum of 4 panels in series to reliably start the MPPT.
2) Since the Impp is 10.98A and the most the MPPT will take is 11.53A, any parallel strings will be over paneling the MPPT.
3) The most number of panels that can be put in series without going over the 425V limit is 425/49.6=8 panels. However, that would leave almost no margin for even cool temperature voltage rise let alone cold temp voltage rise. 7 panels in series would give you ~22% margin for voltage rise and that would be good for all but the most extreme cold weather.
4) So.... the best configuration would be 7 panels in series for each MPPT input.

EDIT: Corrected the vollowing to use 500V as the max
Since you have 15 panels..... the question becomes "can you put 8 panels on one of the MPPT strings?" With the 8 Panels, you will have 49.6x8=396.8V @ 25C. That should operate correctly, but as it gets colder, the voltage will rise. If I am reading the spec correctly, there will be no damage below 500V. This means you have about 26% margin for temperature rise which is fine for the most extreme cold areas.


Now we have to understand what the MPPT will do between 425C and 450C. Will it not turn on? will it work but not try to track the voltage? Unfortunately, I just don't know so it is hard to advise you.

Note: For more information about adjusting Voc for temperature, please review this:
 

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wattmatters

Solar Addict
Since you have 15 panels..... the question becomes "can you put 8 panels on one of the MPPT strings?" With the 8 Panels, you will have 49.6x8=396.8V @ 25C. That should operate correctly, but as it gets colder, the voltage will rise. If I am reading the spec correctly, there will be no damage below 450deg. This means you have about 12% margin for temperature rise which is not very much.
I think you mean no damage below 450V.

I read the inverter specs to mean the Voc limit is 500V but the MPPT operating range is 125-425V with 250-425V being the preferred voltage range for performance. Above the MPPT operating range presumably high voltage protection takes effect, initially derating the inverter production until high voltage shut off is invoked.

With panel Voc of 49.6V then up to 8 panels per string would be fine unless it's a particularly cold climate at which I would limit strings to 7 panels. In my climate you could do 9.
 

FilterGuy

What, me worry?
I think you mean no damage below 450V.
Oops.... Good catch. Sorry for the confusion. I will update my previous post.

I read the inverter specs to mean the Voc limit is 500V but the MPPT operating range is 125-425V with 250-425V being the preferred voltage range for performance. Above the MPPT operating range presumably high voltage protection takes effect, initially derating the inverter production until high voltage shut off is invoked.
That's the rub, isn't it?
Since we don't know what the specs really mean, we don't know how the MPPT will behave. I know of at least one other MPPT that has a safety range above its operating range where it just shuts off. Damage does not occur till you get above the safety range.

BTW: With 8 in series, the voltage will reach 425V at about -1C. I am not sure having the MPPT shut off at the freezing point would be a very good design in most areas. The OP needs clarity on the MPPT behavior in order to decide what to do.

With panel Voc of 49.6V then up to 8 panels per string would be fine unless it's a particularly cold climate at which I would limit strings to 7 panels.
When I redid the numbers, I found that he has ~26% margin with 8 panels. That is more than enough for almost any climate. I am not worried about damage, but I do wonder about the functionality in the cold.
 

mahdi89

New Member
Oops.... Good catch. Sorry for the confusion. I will update my previous post.


That's the rub, isn't it?
Since we don't know what the specs really mean, we don't know how the MPPT will behave. I know of at least one other MPPT that has a safety range above its operating range where it just shuts off. Damage does not occur till you get above the safety range.

BTW: With 8 in series, the voltage will reach 425V at about -1C. I am not sure having the MPPT shut off at the freezing point would be a very good design in most areas. The OP needs clarity on the MPPT behavior in order to decide what to do.


When I redid the numbers, I found that he has ~26% margin with 8 panels. That is more than enough for almost any climate. I am not worried about damage, but I do wonder about the functionality in the cold.
what breaker size should i use?
500v 15A? for EACH PV?
 

FilterGuy

What, me worry?
what breaker size should i use?
500v 15A? for EACH PV?
Since each MPPT has a singel string, a breaker is not required. However, if you want to reamain code compliant a disconnect is. Some people use breakers for disconnects. In your case any 2-pole DC breaker or switch rated for 18A or more should work. (You are supposed to be able to disconnect both the positive and negative. I came up with the '18A' using the 1.55 multiplier that NEC requires. Some of this is covered in this resource:

 
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