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High (250V) Maximum Voltage Ratings?

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tmckenna

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So I seem to be a bit confused at the moment. Looking at charge controllers and I've noticed that Victron has controllers that are rated up to 250V "Maximum PV open circuit voltage". My main question is, is this high voltage rating for large Solar systems that are all wired in Series? I was planning on wiring my panels in parallel to keep the voltage at 12V. Is one method better than another?
 
Last edited:
Parallel adds current. Series adds voltage. 8 100W panels in parallel may push 50A @ 17V, which is lossy. However, those same panels in a 4S2P configuration will be closer to 68V/12A - very little loss from wiring unless long distance.

Higher voltage MPPT can be a little more efficient in lower light conditions.

Note that PWM controllers REQUIRE you to wire you panels in parallel.

MPPT controllers allow the flexibility of high voltage, low current PV input.

100/150/200 and 250V ratings are typical for "consumer" MPPT charge controllers. Outback makes the FM100, which goes up to 300V. Some of the MPP Solar/Growatt units have 250-450V ranges.

The highest you'll typically find is 600V.
 
snoobler said:
Parallel adds current. Series adds voltage. 8 100W panels in parallel may push 50A @ 17V, which is lossy. However, those same panels in a 4S2P configuration will be closer to 68V/12A - very little loss from wiring unless long distance.

Higher voltage MPPT can be a little more efficient in lower light conditions.

Note that PWM controllers REQUIRE you to wire you panels in parallel.

MPPT controllers allow the flexibility of high voltage, low current PV input.

100/150/200 and 250V ratings are typical for "consumer" MPPT charge controllers. Outback makes the FM100, which goes up to 300V. Some of the MPP Solar/Growatt units have 250-450V ranges.

The highest you'll typically find is 600V.
Click to expand...
So those voltages are in fact for systems with many panels wired in series. I didn't realize there was so much loss when dealing with parallel wiring. Victrons 250V rating should be plenty for my intentions, I just never really planned to wire them in series rather than parallel.
 
I paid close to $1000 for my 250/100. Are you sure that's what you need?

A balance of series and parallel often yield better results.
 
snoobler said:
I paid close to $1000 for my 250/100. Are you sure that's what you need?

A balance of series and parallel often yield better results.
Click to expand...

Im hoping for over 1000w so it seems like I'm between the 150/100 and the 250/100
 
How many panels are you planning in running? I doubt you will need an actual 100amp controller if you have less than 15 panels.

You could wire 12 panels in series, and still be under the 250VOC and only 8-9amps. Unless you have 50+ panels (which wouldn't be very smart with 100watt panels).

Edit, I just read your post right above, which means 10 panels. You can get away with A LOT less controller!
 
Lt.Dan said:
How many panels are you planning in running? I doubt you will need an actual 100amp controller if you have less than 15 panels.

You could wire 12 panels in series, and still be under the 250VOC and only 8-9amps. Unless you have 50+ panels (which wouldn't be very smart with 100watt panels).

Edit, I just read your post right above, which means 10 panels. You can get away with A LOT less controller!
Click to expand...
Ideally I would do maybe 7, 24V 200watt Panels, so something like 168 volts and 1400 watts. What controller would you recommend for a setup like that?
 
12v makes it much more difficult. In all reality, you are correct and would probably want a 250/80 or 100. I assumed you would be using a higher voltage battery, and you know what they say about assuming... ?
 
Midnight Classic is available for 150V, 200V, 250V. The higher voltage ones are lower current (lower wattage) and cost more.
So among them the 150V model supports the most watts per dollar.

tmckenna said:
Ideally I would do maybe 7, 24V 200watt Panels, so something like 168 volts and 1400 watts. What controller would you recommend for a setup like that?
Click to expand...

"24V" panel is probably 44Voc, so 7 in series is over 300V just at nominal temperature. Higher when cold.
So one more panel for 8 total, wired 4s2p, and a 200V controller. Possibly! Depends on just how cold your location; this is on the edge.

tmckenna said:
I'd be using 12V
Click to expand...

8 x 200 = 1600W. 1600W/12V = 133A
But it is probably OK if you don't capture all the power at peak.

How about 6 x 200, wired 3s2p for 1200W. That's 100A or less. The Midnight Classic 150/96 would be a good fit (again depending on your location's record cold temperature and exact panel specs.)

If you used a 24V battery this would be less expensive.

Lt.Dan said:
12v makes it much more difficult. In all reality, you are correct and would probably want a 250/80 or 100. I assumed you would be using a higher voltage battery, and you know what they say about assuming... ?
Click to expand...

And then there's my favorite technique: Orient the two parallel strings differently, one for morning sun and one for afternoon. That reduces peak current to just 70% as much.
 
I'm also planning on using the Touch Screen GX System Monitor so I'd want to go with a victron solar controller to appear on that
 
tmckenna said:
I'm also planning on using the Touch Screen GX System Monitor so I'd want to go with a victron solar controller to appear on that
Click to expand...

A 150/100 is about $150 less than a 250/100.

24V panels are about 47Voc, so you can only run 2S. You might be better served by 60 cell panels that you could run 3S on a 150/100

Santan sells 240W panels for $45. 6 of those would yield almost 1500W in a 3S2P array.

The MPPT is bluetooth, so you get a lot of info. A GX device's biggest benefit is in integrating multiple Victron components (MPPT, Inverter, BMV/Smartshunt). If you are just getting a GX to monitor your MPPT, save your money... unless you want to log the data in VRM.
 
snoobler said:
A 150/100 is about $150 less than a 250/100.

24V panels are about 47Voc, so you can only run 2S. You might be better served by 60 cell panels that you could run 3S on a 150/100

Santan sells 240W panels for $45. 6 of those would yield almost 1500W in a 3S2P array.

The MPPT is bluetooth, so you get a lot of info. A GX device's biggest benefit is in integrating multiple Victron components (MPPT, Inverter, BMV/Smartshunt). If you are just getting a GX to monitor your MPPT, save your money... unless you want to log the data in VRM.
Click to expand...
I was planning on doing a victron multiplus as well so the monitor would be to monitor solar array output and total system drawer (of both AC and DC circuits)
 
Don't forget the BMV-702. You don't need bluetooth with a GX device, and you'll want temperature sensing.
 
TL;DR
If you want % SoC of your battery, you must get a BMV.

-------------------------

Victron doesn't work that way. There's a device for everything.

Want to provide AC power and charge from AC power? Inverter/charger
Want to charge batteries with solar? MPPT
Want to measure and report battery data? Battery monitor
Want to tie all of the above together and get extra features? GX device.

The GX doesn't know anything by itself. It's an aggregator with some added functions based on the incoming info. Without a device reporting % SoC, then it won't report % SoC.

The Multiplus has a battery monitor, but it only knows what goes in and out of the Multiplus. The voltage read by the Multi is influenced by the current, so it's not accurate.

The MPPT knows what goes out of it. Its voltage is also influence by the current, so it's not accurate.

Nothing knows the net flow in and out of the batteries except a battery monitor, BMV-702. It takes direct open circuit voltage readings, temperature readings and counts current to establish % SoC. It also provides voltage compensation temperature data (MPPT's default setting is sub optimal) and applies Peukert.

An example of added features from the GX: My 3kW array can easily overpower my deteriorated 12kWh of FLA. To keep from cooking it, I shouldn't push more than 30A into the batteries @ 48V. My SCC can do almost 60A. I could instruct the MPPT to only put out a max of 30A, but that's silly business. With a GX device and DVCC enables, I can tell the GX to limit my charging to 30A from all sources. If more power is needed for loads it will pull additional solar beyond 30A to power the loads.
 
snoobler said:
TL;DR
If you want % SoC of your battery, you must get a BMV.

-------------------------

Victron doesn't work that way. There's a device for everything.

Want to provide AC power and charge from AC power? Inverter/charger
Want to charge batteries with solar? MPPT
Want to measure and report battery data? Battery monitor
Want to tie all of the above together and get extra features? GX device.

The GX doesn't know anything by itself. It's an aggregator with some added functions based on the incoming info. Without a device reporting % SoC, then it won't report % SoC.

The Multiplus has a battery monitor, but it only knows what goes in and out of the Multiplus. The voltage read by the Multi is influenced by the current, so it's not accurate.

The MPPT knows what goes out of it. Its voltage is also influence by the current, so it's not accurate.

Nothing knows the net flow in and out of the batteries except a battery monitor, BMV-702. It takes direct open circuit voltage readings, temperature readings and counts current to establish % SoC. It also provides voltage compensation temperature data (MPPT's default setting is sub optimal) and applies Peukert.

An example of added features from the GX: My 3kW array can easily overpower my deteriorated 12kWh of FLA. To keep from cooking it, I shouldn't push more than 30A into the batteries @ 48V. My SCC can do almost 60A. I could instruct the MPPT to only put out a max of 30A, but that's silly business. With a GX device and DVCC enables, I can tell the GX to limit my charging to 30A from all sources. If more power is needed for loads it will pull additional solar beyond 30A to power the loads.
Click to expand...
Semi unrelated but any idea what purpose the "Orion" serves in this wiring schematic?


I guess I don't understand the "needed for DC loads with minus connected to chassis" part
 
tmckenna said:
Semi unrelated but any idea what purpose the "Orion" serves in this wiring schematic?


I guess I don't understand the "needed for DC loads with minus connected to chassis" part
Click to expand...

In the Victron schematic, I see positive wire connecting LFP battery, starter battery, alternator, inverter.
Negative of LFP battery goes through BMS.
(Some systems might have negative or chassis tied, common, but not this one)

If you connected a DC load directly from LFP to chassis, it would bypass BMS.
Orion is shown as an isolation circuit which instead provides a positive connection that can be controlled, disconnecting load from LFP if necessary.

Note "Other DC Load" with positive and negative connections that you could use without needing Orion. That has negative isolated fro chassis.
 
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