I have 4x660W panels with Voc=45,9 V and Isc=20,11A. Outdoor temperature -20C shall be considered.
So for -20 Voc=0,25/100x(25+20)*45,9+45,9=51,06 V.
Series connection gives 102,12 V. This is too much for 100/50 mppt.
But we have such low temperatures in winter time only, when max irradiance is below 300W/m2, so panel actually has Voc=42,9V (i have precise value only for 800W/m2 but see from graph, that for lower irradiance it is maybe even 1V below) for +25, so for -20 it shall have Voc=0,25/100x(25+20)*42,9+42,9=47,7 V 2x47,7=95,4< 100V
What do you think, can use victron 100/50A mppt for 2s2p connection? All panels will have incline 35deg, first will be directed east and second west.
You are correct, its oversized, but i have this panels for free and looking how to install them. Location is remote, so transportation is almost price of the panel, so just selling them will not work.
I have 4 panels 660W at 1000W/m2. In June and July (at 60deg north) we have global solar irradiance up to575 W/m2. So we get maximum installed power 1520W for June/July during maximum hour and expected solar energy output from panels 12kWh/day. For October pvgis calculates peak production 500W and daily production 2,4kWh/day.
I don’t plan to charge battery with 1C, considered not over 0,5C.
Daily consumption on site during summer is around 25% of battery capacity.
Why 100/50 is out? is it wrong to consider decrease of open circuit voltage depending on total irradiance?
As I understand if I’m trying to put them into parallel work, communication between units it’s necessary to optimize performance and avoid “conflicts”? Or i’m wrong?
Hi Havoc, many of these fundamentals can be found in the manuals and free training at professional.victronenergy.com
With multiple chargers you do want to coordinate charging.
You can do this on small, often DC only, systems with smart networking.
On larger systems, you would use a GX and all the devices would be connected there and DVCC used to coordinate the devices and to choose shared sensors for current etc (worth a read of chapter 11 of the Cerbo manual).
With lithium batteries that are managed, then the battery will control all the chargers.
That may be fine for your application, but it doesn’t suit all applications.
Not sure how your shunt can share its data without some form of networking present, which is the main point.
For typical use cases, with battery management, the system will want to vary its parameters and shared comms are needed for that.
Where installs aren’t constrained by PV, the ability to charge may well exceed the battery requirements or be above the desired C rating, thus centralised control is helpful.
So, coordination is best practice, but not mandatory.
It is up to the system designer to determine what is appropriate for their configuration, knowing the options helps the decision making.
Which is networking and one of the mechanisms I described earlier as one of the ways to connect devices, after you queried why he wanted to connect mppt’s in the first place.
The sarcasm is unnecessary.
No real point for this and actually physically no space on the south wall.
Still looking for engineering manual for parallel connecting solar panel strings with different orientation.
From I-V characteristic graph of my panel I see, that MPPT points for panels with irradiation 200W/m2 and 800W/m2, are not so far from each other (around 5V). For working at MPPT point of better illuminated panel I will get decrease around 10% from less illuminated panel.