Off-Grid System withdrawing less wattage than expected from the solar panels

[marlinb619]

Hey guys, I have 2 of the BluePower SP6548 SOLAR INVERTER. I installed 20 panels of CS3N - 395MS.
On paper, each solar panel generates 395W with full direct sunlight. That means 7,900W in total. All panels are on the same roof at the same angle.
I have 2 inverters split phase, and at max sunlight, I get 2.5KW on each. (5KW total)

Why am I not getting anywhere around 7.9KW? Will some dust on the panel make the wattage go that low? or does the inverter has any kind of wattage/heat safety protection?

 

[rodrick]

If they are not at the optimal angle they will produce lower the dust is minimal on output do you have any shading

 

[SamDeleted]

Theoretically maximum & real world production are very different things


But does seem a little low in full sun ?


What are you making over a whole day ?

 

[robby]

I think the better question is why am I not getting 6.5Kw.
unless your getting perfect sunlight and the Temperature is very cool you will not see the full 7.9Kw.

the 5KW is low, what is your string configuration and are you maxing out the current that the MPPTs can handle?
Most will clip the amperage coming from the array if they are driven pass maximum.

 

[DIYrich]

As an off grid system, do you have enough load for 7kW? How big are your batteries?

 

[marlinb619]

Theoretically maximum & real world production are very different things


But does seem a little low in full sun ?


What are you making over a whole day ?

I cleaned the panels today, and I was able to get 6KW MAX in full sunlight. Still missing 1.8KW according to the rating on the panels, but not sure if that's normal.

 

[marlinb619]

As an off grid system, do you have enough load for 7kW? How big are your batteries?

Yes, it's enough.
I have 30KW Battery capacity.

 

[MrM1]

Today my 5.1k array was producing 3100 watts in full sun at solar noon. Why?
1. The 32kWh 24v battery bank was 90% charged . Chargers where tapering down
2. I had 535 watts of load

The array will produce over 4400 watts in full sun only rarely when there is enough load and / or demand for charge . It seems to be able to sustain about 4000 watts +/- in full sun. But an array only produces what is required.

Are you demanding full powerful from your array?

 

[Texican]

when you say full sun. do you mean at noon to 1 pm ?

 

[MrM1]

when you say full sun. do you mean at noon to 1 pm ?

And there is even a difference between noon (12pm) and Solar Noon. And definitely a difference between Dec 21 and Jun 21. My best production is in March. A balance of Temps and sun angel

 

[yabert]

I cleaned the panels today, and I was able to get 6KW MAX in full sunlight. Still missing 1.8KW according to the rating on the panels, but not sure if that's normal.

Read at Inverter screen or manually monitor with quality instruments?
To me, you can't rely on those chinese inverter to have accurate reading.

 

[Hedges]

Hey guys, I have 2 of the BluePower SP6548 SOLAR INVERTER. I installed 20 panels of CS3N - 395MS.


Why am I not getting anywhere around 7.9KW? Will some dust on the panel make the wattage go that low? or does the inverter has any kind of wattage/heat safety protection?

The impact of dust is surprisingly low.

"ELECTRICAL DATA | STC* 395W"
"ELECTRICAL DATA | NMOT* 296W"

NMOT is realistic temperature, but also 80% of full sun.
Between STC and NMOT is PTC, full sun but realistic temperature.

20 x 296W = 5920W

I cleaned the panels today, and I was able to get 6KW MAX in full sunlight. Still missing 1.8KW according to the rating on the panels, but not sure if that's normal.

To know if 6kW is correct or low, you need measurement of sunlight strength.

 

[wattmatters]

At this time of year you are unlikely to attain peak solar PV output unless your panels are optimally aligned. But putting that to one side...

Yes, it's enough.
I have 30KW Battery capacity.

So about 585 Ah of battery.

I cleaned the panels today, and I was able to get 6KW MAX in full sunlight. Still missing 1.8KW according to the rating on the panels, but not sure if that's normal.

What is the max charge current setting in the inverters?

If those inverters are the same as the MPP LV6548 then the default charge current is 60 A, which when doubled for two inverters is 120 A. If you have not changed the max charge current setting, then the most you will see generated is in 6000 - 6500 W range plus whatever household loads there might be at the time the batteries are charging.

To put 7.9kW into the batteries requires a charge current of around 150-160 A.

Whether that's a good idea or not will depend on whether you think pumping 160 A into ~585 Ah of battery is wise. I think 120 A is a reasonable limit, but consult your battery's recommended charge specifications. Many will recommend charging at 0.2 C (0.2 x 585 Ah = 117 A).

 

[SamDeleted]

I cleaned the panels today, and I was able to get 6KW MAX in full sunlight. Still missing 1.8KW according to the rating on the panels, but not sure if that's normal.

Yea sounds normal to me , you're not missing 1.8kw ... You're gaining 6kw! It's fantastic that's loads of free electric

 

[sunsurfer]

every panel I have ever owned only hit full power(and higher) was on a clear sunny and COLD winter day.

 

[740GLE]

Cool spring and fall days are your best bet for peak KW values in my area (Northeast). Less haze in the air due to lower humidity, and panels stay cooler, thus are more efficient.

If I had 7.2kw installed and saw 6kw peak output, I’d be very happy with that results.

Now don’t be surprised if you struggle to hit that same 6kw as the heat/humidity starts to crank up.

 

[740GLE]

At this time of year you are unlikely to attain peak solar PV output unless your panels are optimally aligned. But putting that to one side...


So about 585 Ah of battery.


What is the max charge current setting in the inverters?

If those inverters are the same as the MPP LV6548 then the default charge current is 60 A, which when doubled for two inverters is 120 A. If you have not changed the max charge current setting, then the most you will see generated is in 6000 - 6500 W range plus whatever household loads there might be at the time the batteries are charging.

To put 7.9kW into the batteries requires a charge current of around 150-160 A.

Whether that's a good idea or not will depend on whether you think pumping 160 A into ~585 Ah of battery is wise. I think 120 A is a reasonable limit, but consult your battery's recommended charge specifications. Many will recommend charging at 0.2 C (0.2 x 585 Ah = 117 A).

Time for more batteries!!!!

 

[Mattb4]

7,900w rating and you are getting 6,000w peak amounts to 76% efficiency. Low but certainly not totally out of line. Most people report around 75-80%

The more important statistic is overall wh (watt-hours) produced during the day. Once you get that number you can divided by the 7900w panel rating to get your average hours of production. This is likely in the 4-6 hour range in this time of year. Say you are getting 43,450wh on the day. This means you are averaging 5.5 hours.

Knowing your average (in each Season) will help you establish what loads you can meet.