Solar Inverter Specifications

Abdel

I have small question related to off-grid inverter specification  and I hope to get help.
In the 11 KW inverter datasheet , there is Max PV input current 18A , which means that the PV module current must not exceed this value, but there is also Maximum solar charging current which is 150A. I confused between them. What maximum solar charging current means for the modules and what is the difference between Max PV input current and Max solar charging current ?

Photowhit

Abdel said:

I have small question related to off-grid inverter specification  and I hope to get help.
In the 11 KW inverter datasheet , there is Max PV input current 18A , which means that the PV module current must not exceed this value, but there is also Maximum solar charging current which is 150A. I confused between them. What maximum solar charging current means for the modules and what is the difference between Max PV input current and Max solar charging current ?

Without seeing the spec sheet, it sounds like a high voltage input. What does it say for the range of voltage input? 300-600volts?

The 18 amps would represent just a couple or a few strings of panel. Say you had 300 watt 72 cell panels which would have a VMP of 37 to 38 volts, and an IMP around 8 amps, so a string of 12 would be 3600 watts at 8 amps.

Output at 48 volts for your battery bank would be 3600/48= 75 amps so you should be able to handle 2 string in parallel, maxing out your charging capacity at 7200 watt array, producing 16 amps input and out putting about 150 amps.

Photowhit

BTW - Welcome to the forum!

Vic

... And, to add a bit to what Photowhit said,

With Charge Controllers and inverters with built-in charge controllers, that have limits on maximum PV input current, the designer should use total PV string Isc for this calculation.

FWIW, Vic

Abdel

https://www.mppsolar.com/v3/catalogs/PIP-MAX
Here is the inverter specifications 

Photowhit

So it appears these are 230 volt inverters, with no 120 volt output (single leg of 240V).
Are you in Europe? This doesn't appear to have a center tapped neutral to provide 120 volt output...

It has the info all over the place, I really hate that the info isn't in a simple spec sheet. In the spec sheet part it says 100 volt minimum input and on the first page it says "H I G H P V I N P U T 5 0 0 V ( V O C )" so that would represent up to about 380-400 volts VMP. Likely stay around 300 volts VMP to be safe, very cold weather can push VOC higher than the panel rating.

It also says "D U A L M P P T I N P U T ( 4 8 V o n l y )" It doesn't say so you'll need to check if this means it can handle 2 different sized strings in essence have 2 separate MPPT charge controllers, I'd make that assumption, but it's poorly outlined.

It also says "Frequency Range 50 Hz/60 Hz (Auto sensing)" Not sure how you can have a device 'auto sense' what output it needs to have. This would usually be information for a grid tied inverter. It also says "Off Grid" and "Battery Optional" so it may be a hybrid inverter...

At this point in reading specs with odd info, I assume they can't produce a brochure I can understand I don't want to do business with them.

RCinFLA

The 18A PV input is with a high PV DC voltage panel array input.

I am guessing you are talking about a Sol-Ark inverter.  Other HF all-in-one inverters operate in simlar way.

Sol-Ark has two SCC controllers, each with maximum of 6.5kW but combined maximum of 12kW.

Say you have Vmp array of 400vdc at Imp of 15 amps for 6000 watts to single SCC input.

SCC controller HV DC boost circuit is about 98% efficiency.  HV DC to battery downconversion efficiency is about 94%.  Net conversion from PV to battery is 0.98 x 0.94 = 92%.

So 6 kW PV input (400v x 15 amps) downconverts to 6kW * 0.92 or about 5.5 kW to charge battery.  If battery is 50 vdc then battery charging current will be 5500 watts / 50v = 110 amps.  This is just for one of the two SCC controller inputs.

In HF hybrid inverters, all power exchange goes through a high voltage DC node, with the exception of AC input pass-through.  The inverter internal HV DC is about 500 vdc which is why the max PV input voltage is 500 vdc.  The PV power converted to HV DC node could also go directly to the HV DC to AC PWM sinewave AC output.  The battery to HV DC converter is not involved with this PV to AC output conversion.

When AC output is only coming from battery it first gets upconverted to HV DC node then AC PWM sinewave chopper takes it to AC output.

AC output may partly come from PV and partly come from battery, or partly from AC input and partly from PV input.