victron mppt solar question

[taliv]

datasheet for panel in question

https://www.renogy.com/content/RNG-160D-SS/160D-SS-Datasheet.pdf

datasheet for mppt 100/30 in question

https://www.victronenergy.com/upload/documents/Datasheet-SmartSolar-charge-controller-MPPT-100-30-&-100-50-EN.pdf

panel datasheet says shortcircuit current is 8.37A
optimum current and voltage are 7.92A and 20.2V respectively

mppt datasheet says rated for 30A and max PV array short circuit current is 35A and anything over could damage it

8.37 x 4 = 33.48A which is less than 35A

so does that mean i could wire 4 of these panels in parallel without damaging the mppt 100/30?

I think what's confusing me is converting from the operating PV voltage of around 20-22v to the battery which is somewhere around 14.4v. On the 160w panel, 160w / 20v = 8A so that makes sense. but If I convert that to 14.4v, then 160w / 14.4v = 11.1A and if I put 4 panels in parallel that would be 44.4A (43.5 at 98% efficiency) leaving the MPPT going into the battery, right? 43.5A exceeds both rated and max current of 30 and 35A. But since the datasheet says "max PV" i assume i can do 4 panels and that the output side can handle it? Or should I drop to 3 panels? (24A @20v in and 33.3A @ 14.4v out?)

how many amps are going into my battery per panel? 8A? or 11A?

 

[rayra]

datasheet for panel in question

https://www.renogy.com/content/RNG-160D-SS/160D-SS-Datasheet.pdf

datasheet for mppt 100/30 in question

https://www.victronenergy.com/upload/documents/Datasheet-SmartSolar-charge-controller-MPPT-100-30-&-100-50-EN.pdf

panel datasheet says shortcircuit current is 8.37A
optimum current and voltage are 7.92A and 20.2V respectively

mppt datasheet says rated for 30A and max PV array short circuit current is 35A and anything over could damage it

8.37 x 4 = 33.48A which is less than 35A

so does that mean i could wire 4 of these panels in parallel without damaging the mppt 100/30?

I think what's confusing me is converting from the operating PV voltage of around 20-22v to the battery which is somewhere around 14.4v. On the 160w panel, 160w / 20v = 8A so that makes sense. but If I convert that to 14.4v, then 160w / 14.4v = 11.1A and if I put 4 panels in parallel that would be 44.4A (43.5 at 98% efficiency) leaving the MPPT going into the battery, right? 43.5A exceeds both rated and max current of 30 and 35A. But since the datasheet says "max PV" i assume i can do 4 panels and that the output side can handle it? Or should I drop to 3 panels? (24A @20v in and 33.3A @ 14.4v out?)

how many amps are going into my battery per panel? 8A? or 11A?

The output / charging current amperage of the Victron 100/30 is 30A. Doesn't matter how much juice above that is available from the panels, the Victron 30 is only passing 30. There is not higher amp to 'handle'. The device itself won't pass in excess of 30A, by design. It is in effect a transformer with a 30A @14V+ limit on its output.

Too, you are mistakenly calculating on max efficiency rating of your panels, which you'll never see in the field. So it is likely that your 4 panels will never generate enough to exceed the max rating of the 30. Or you just buy the 50A model to be sure.

Too, if your battery is full, yoru solar system isn't even going to pass 30A, the controller will put things in 'float' as the battery nears capacity and it will only pass a couple amps.

If you plan a lot of daytime electrical usage, as with a fridge, blender, music, charging or powering electronic devices, the whole 'glamping' suite - which you seem to be intending, as demonstrated by 4 panels - then you have best get the 50A rated victron so that you can pass every bit of juice your panels can generate.

 

[nathane]

Wire in series?

 

[NatersXJ6]

I’m am far from an expert, but I think you will have to wire in series in order to generate the minimum voltage to start the power generation. I just recently installed my first system, but I recall reading something in the Victron literature (I used 2x 100W and the 75/15 MPPT) that talked about minimum and maximum voltages for MPPT.

 

[nathane]

I think this too. I'm running 5 panels, 4 x 175w and one 360w into a big mppt 150 unit in series. All Victron. 9ish A set up at obviously higher voltage.

 

[Alloy]

At the rated output (higher is possible but rarley happens) it is 11A per panel.

Set up in series.......4 panels at 7.92A / 20.2V will be 7.92A at 80.8V.

or

Set up in parallel......4 panels at 7.92A / 20.2V will be 31.68A at 20.2v

Higher voltage is better but 80v is dangerous so probably set up 2 panels (strings) in series and then parallel those strings

A 100/30 will limit the output to 30A. Best to get a larger controller.

 

[taliv]

ok for everyone who said wire in series.... the datasheet says max PV open circuit voltage is 100v, so does that mean 20v x 4 = 80.8, so 4 panels in series would be well under the 100v max? and higher voltage means more efficient transfer over a fairly long cable, as opposed to the higher amps of a parallel config?

is 80v much more dangerous than 40v?

either way, series or parallel, 4 panels is going to exceed the 30a output, so i'd pretty much be getting 30a. (i know, based on clouds and trees etc, i'll get a good bit less than that. i'm just trying to make sure i have the formulas right.

If you plan a lot of daytime electrical usage, as with a fridge, blender, music, charging or powering electronic devices, the whole 'glamping' suite - which you seem to be intending, as demonstrated by 4 panels - then you have best get the 50A rated victron so that you can pass every bit of juice your panels can generate.

i've been working from home for a tech company for the past 20 years. so i am just running the normal overlanding loads (fridge, water pump, lights) but also a couple laptops and phones. no blenders or glamping stuff. wanting to stay out a lot longer as opposed to just on my vacations, so i'm trying to figure out what it would take

I’m am far from an expert, but I think you will have to wire in series in order to generate the minimum voltage to start the power generation. I just recently installed my first system, but I recall reading something in the Victron literature (I used 2x 100W and the 75/15 MPPT) that talked about minimum and maximum voltages for MPPT.

i don't understand this. manual says PV has to exceed Vbat +5v. sooo... if PV is 20 and the battery is at 13v, then 20 > 13+5 so it would start.
that would be the case if i have only a single panel. so wiring in series would give 40 or 60 or 80v, but even 20 is enough to start. right?


thanks to everyone

 

[NatersXJ6]

Agreed with Verkstad on all points. Your panels max is 20, they can also do a lot less.

I would series all your panels. 60-80V on smaller wire from panel to controller is going to be happier than lots of amps but not enough voltage to start the charge.

higher voltages are always more dangerous, but I am not concerned about the 110 outlet from my inverter...

proper wiring, insulation, fusing, grounding should protect you

 

[rayra]

old saw 'it's not the volts that kills you, it's the amps'

/somewhere I have an old photograph of me at the Montreal Expo touching a huge static ball (tesla coil?) and every long hair on my head standing straight out like a dandelion

Personally I wouldn't go serial just to preclude one panel connection or panel fault severing power from everything upstream of it. And check the start voltage requirements on the unsechsy PWM controllers to see if they run lower.

 

[jonyjoe101]

with mppt you do need higher voltage to get an increase in amps. With a 21 volt panel you won't see any improvements over pwm. I never saw any with my controllers.

As an example I used a 120 watt 21 volt panel and connected to both a pwm and mppt controller, both gave me 6 amps output. When I got a larger 240 watt 36 volt panel and connected to a pwm controller I got about 7 amps, when I connected same panel to a mppt controller I got 12 amps.

If you connect in parallel and aren't seeing good amp output you can always try connecting in series, the mppt controller can handle it. If your panels are flat on the roof you probably will never see 30 amps except in the summer when you have a depleted battery, but you do want to get every amp possible from your panels especially in the winter and cloudy weather.

 

[taliv]

I was thinking I might drop to 2 or 3 panels. If I was at 4, doing 2 in serial and paralleling them seems like a good idea. But we will see

 

[Alloy]

I was thinking I might drop to 2 or 3 panels. If I was at 4, doing 2 in serial and paralleling them seems like a good idea. But we will see

You'll never have too much solar.

 

[nathane]

Yesterday we were getting 900W from our system, at mad current of around 9A that must have been around 100V going into the mppt controller. No shocks, nothing melted! Just install them in series with a properly sized controller and you will be fine, reduce wireline losses and be happy and safe with thinner cables. You need to be careful when you have exposed wires during installation, that's true, but once installed this isn't an issue. During installation just tape cardboard over the panels and the pv won't do anything. Parallel brings all sorts of unnecessary additional complexity I think for an array of this size.