Need advice on, 1KW inverter but manual says, RECOMMENDED MAXIMUM PV POWER @ 1500W

Chan

Based on this product and manual...
http://www.eastups.com/en/products_show_48_159.html

My current panel is:
MY PANEL WITH 300W
VMP: 37.13
IMP: 8.08

INVERTER SPECS is 1000W: http://www.eastups.com/upload_files/i_20150826_1706242229.pdf
MAX INPUT VOLTAGE: 150Vdc
Operating Voltage : 65-120Vdc
Recommended MAX PV power : 1500W

I am going to series my panel up to 4 to get
vmp : 148.52Vdc
imp: 8.08A
Total Wattage : 1200W

So based on my configuration : Since the MAX INPUT VOLTAGE of the inverter is 150Vdc...
Can I connect it using my configuration, but since the RECOMMENDED MAX PV POWER IS 1500W...
Can I still add another 300W panel to achieve the 1500W Recommended max pv power, but going beyond the 4 series setup, i would be breaking the MAX INPUT VOLTAGE OF 150Vdc...

Can anyone help me on this..
Thanks in advance.

Raj174

Hi Chan,

So I take it that this is an inverter that has an MPPT charge controller built in and you have a 48 volt battery bank. If that is the case then I would recommend  3 panels in series. Even though it may be possible to put 4 in series, it would be inefficient due to wattage loss to heat production in the charge controller.  Cloud edge effect is something else to consider. It could easily send the PV voltage over 150 volts. Also, It also depends on what kind of batteries you have and the capacity of the battery bank. With 3 panels in series, if you have an AGM battery bank the minimum capacity would be about 80 amp hours at 48 volts. If you have lead acid batteries the minimum capacity would be about 120 amp hours at 48 volts.   

Chan

Based on the inverter:
INVERTER SPECS is 1000W: http://www.eastups.com/upload_files/i_20150826_1706242229.pdf
MAX INPUT VOLTAGE: 150Vdc
Operating Voltage : 65-120Vdc
Recommended MAX PV power : 1500W

Why did it indicate a recommended max pv power of 1500w but only accepts 150vdc and 1000W specs?

vtmaps

Raj174 said:

Cloud edge effect is something else to consider. It could easily send the PV voltage over 150 volts. 

Not so.  Cloud-edge effect does not raise the voltage, it raises the current. 

Chan,
Do NOT connect the four panels in series or you will damage the controller.   When you figure the number of panels you can put in series, you must use the Voc, not the Vmp.  Your panels probably have a Voc of about 46-47 volts.  Three in series could be 140 volts.  I don't know where you are located, but if you have any cold weather the voltage of three in series will exceed 150 volts and damage your controller.

Your panels are 72 cell panels.  They can be problematic with a 48 volt system.   If you put two in series, the Vmp, in hot weather, may not be high enough to operate an MPPT controller.   Three in series may damage the controller in cold weather.  

Some controllers, like the Midnite Classic can deal with 72 cell panels in a 48 volt system better than others.  With three panels in series, the Classic will stop working if the voltage gets above 150, but will not be damaged until the voltage get above 198.  If you put two panels in series, you can change the Classic's MPPT algorithm to 'legacy' mode and it will function with the lower voltages that occur in hot weather.

--vtMaps

Raj174

Thanks for the correction vtmaps.

Chan,

Using the full capability of the inverter would require different panels. Example: six 250 watt panels configured in 2 strings of 3. The resulting PV voltage would be about 90 volts, which is more than adequate  for a 48 volt battery bank. Also the panel VOC would be well below 150 volts.
    

Chan

PANEL 300W
vmp:37.13
imp: 8.08
voc:46.11
isc:8.64
- I was thought that you only have to calculate the vmp and ignore the voc when sizing the inverter
- Philippines here.

Raj174

VOC increases in cold weather and if it goes over 150 volts it will burn out the charge controller. VOC for 3 panels in series is 138 volts. Temperature in the Philippines rarely even below 70 degrees F.
I would say 3 panels in series is ok to use. If the inverter can display VOC voltage, recommend just keeping an eye on it.
4 panels would obviously be to much voltage. 

Chan

So, should I ignore the VOC when sizing since temp rarely goes down 70 degree?

Raj174

I would say 3 panels in series is ok to use. If the inverter can display VOC voltage, recommend just keeping an eye on it.
When sizing PV for 48 volt systems, try keep VMP between 83 and 105 volts and VOC will be ok..

vtmaps

Chan said:

So, should I ignore the VOC when sizing since temp rarely goes down 70 degree?

I would not ignore it.  The temperature only has to dip once to ruin your controller.  Also, when you have a clear, still morning with an air temperature of 70°, the panel temperature will be several degrees lower than the air temperature because of radiative cooling.

Controller damage usually occurs early in the morning.... Your panels will reach full Voc with the first morning light, before the sun has a chance to warm up the panels.

--vtMaps

Chan

vtmaps said:

Chan said:

So, should I ignore the VOC when sizing since temp rarely goes down 70 degree?

I would not ignore it.  The temperature only has to dip once to ruin your controller.  Also, when you have a clear, still morning with an air temperature of 70°, the panel temperature will be several degrees lower than the air temperature because of radiative cooling.

Controller damage usually occurs early in the morning.... Your panels will reach full Voc with the first morning light, before the sun has a chance to warm up the panels.

--vtMaps

ok, Thanks