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How many amps can a victron 100/20 48 volt solar mppt handle? Is this false advertising?

dougw2007

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Oct 21, 2021
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This seems like an easy question but I think I have been scammed. I bought two of these and when I was looking over the text on the box I noticed a huge problem.
I have checked the download data sheet on this and it confirms what I think.
The official name of the controller is 100/20 48. The official name of a similar model line is 100/15 and 100/20.
Those two lines will handle just what the title says. 15 amps at 12 or 24 volts. 100/20 specs are 20 amps at 12 or 24 volts.

But the 100/20 48 appears to handle 20 amps at 12 or 24 volts but only 1 amp at 48 volts. So I bought two of these to run the 4 batteries in series at 48 volts.
But now I am going to have to scale my system down to have two panels that only produce a maximum of 1 amp in full sun.
Panels like that are going to be a lot smaller, many 12 inches by 12 inches.

You would think that the name of the product 100/20 would mean you could run panels like mine that produce 8 amps at 39 volts. But no, 1 map max.

I would appreciate any help on this as I am new at the solar electronics and there seems to be a lot of different ways to connect something. I bought a Victron mutiplus 2 3000 that is 48 volts. I did notice a slight problem on that inverter. It is rated for 3000 watts. I am installing this in a motorhome. With those specs you would think that you could run a 3000 appliance from this inverter. Right? Wrong! You may not be able to do that. Let's say you are planning to use this in the summer. Then you have to derate the the max wattage. If it is 104 F outside you can only run 2200 watts. This year is was 112 F here in Idaho for many days. That would mean you are down below 2200 watts for the max load. Maybe the max would be 2kw from a 3kw inverter.

You could move the inverter into your living space and put it by the air conditioning but now the ac would have to run longer.

This is all explained in the fine print on the data sheet. It is not explained in the marketing hype you usually see.

Victron seems to be the big name brand for solar but with these two things cropping up I am not sure this is the way to go.
 
Which panels? The 100/20 should provide 20A, as long as your input voltage is sufficient. For these Victrons its +5V, so in worst case you should have at least 63V or so (57V + 5V) for a (fully charged) 48V pack.

As for the inverter: 99.9% of the specs are rated at 20-25c (68 - 77F) ambient temps. Cheap stuff tends to overheat,shutdown or fail, decent stuff will reduce output. That MPPT for example is also reducing output >104F.

Aims lab eg specifies ambient temp of max 104F, preferable <77F. At 148F the inverter shuts down. I'm quite sure you will hit this rather soon if you're pulling max power at eg 104F, or even faster when higher.

For these kind of temperature ranges you're better looking into industrial-range stuff (=$$$) since those generally can handle higher temps. Regular/consumerstuff and those kind of high temps will be an issue, on any brand.
 
Thanks for responding. I have four panels that are rated 330 watts and the output voltage is 39-40. I planed on putting two in series for around 80 volts to each charge controller. But the panels put out 8 amps in bright sun and according to the data sheet that would blow out the 100/20 48.charge controller.jpg
 
Not sure where you get from that the 100/20-48 can only handle 1 A charge current. In the datasheet I read one entry that says "1 A" but it assume it relates to the 'load' output. I don't think you need the 'load' output in your motorhome application, do you?

For inverters it is standard in the industry to label them higher than what they can do continuously. The reasoning behind this is that you ought to size the inverter for your peak load (such that it doesn't trip every now and then) and that your average load is usually far lower than this peak load. If you want to draw 3000 W continuously for half an hour or more, a single Multiplus 3000 might be insufficient indeed. On the other hand, if this 3000 W is just a peak load that lasts a few seconds, the Multi 3000 will handle it just fine as it can do 6000 VA peak.
 
I agree about the 1A as referred to the load output, which is unlikely you're going to use.

Those panels should be (just) good to go. With a 2S2P configuration each string provides 80V at max 8A for each string.
So 2 strings parallel would give 16A max PV short circuit current, which is still within acceptable range.

You can't pull full capacity of the panels, since 4x330V = 1320 watt, which is 27A at 48V, while the controller can 'only' do 20A. However, it's safe to assume
- The battery voltage will be close to 52V usually, only at a very low SOC it's lower, thus the current will be more like 25A max
- Panels have some degrading
- 100% rated capacity is unlikely. Add 5-10% losses due to flat mounting, dirt and so on.
- Even at a perfect angle/clean panels, its rated current is only available for short periods, I think about 1-2 hours/day top during summer. And heat will degrade the efficiency also.

In reality, I think you're barely even hitting the 20A, so not much is lost with only using a 20A controller for your panels.

Note: Make sure the MPPT has sufficient ventilation. It will have to dissipate it's generated heat and when pulling 15+A I think it will get pretty warm, so decent cooling is essential
 
Might someone give/link to a discussion of “load current” vs “charge current”?
 
Might someone give/link to a discussion of “load current” vs “charge current”?
Not sure whether this has been discussed already. As far as I'm aware: 'load current' = current drawn through the SCC 'load' output and 'charge current' = current drawn through the SCC 'battery' output. The 'load' output is usually only used where you want the SCC to be the BMS like in solar streetlights.
 
Okay maybe I am not understanding what max load current is. I am connecting two panels in series and then the other two in series and I am going to connect both of the outputs to the 48 volt battery. (4 12 volts in series)

In the chart I posted it seems to show what I would consider normal data points the 10 amp can handle 15 amps along with the two 15 amps ones handling 15 amps. That all looks good to me. But then when you jump to the 10 20 48 one now it is showing on the same line 20 20 and 1amp. Which seems to say at 12 volts you can have 20 continuous current and if you double the the 12 to 24 you can still have 20 amps. But if you double the voltage to 48 you cut the continuous current by over 90 percent.

I am thinking that the continuous current is what the controller can output to the battery?

At the top of the chart is says the controller can handle 1160 watts and 20 amps at the 48 voltage.

On the surface it looks like I bought the right controllers (although the victron calculator that I just noticed recommends the 150 35? That seems to be unnecessary for these panels).

On the side of the packaging it says max continuous current 1 amp. Sort of scared me.

So are these controllers going to work?
 
Okay maybe I am not understanding what max load current is. I am connecting two panels in series and then the other two in series and I am going to connect both of the outputs to the 48 volt battery. (4 12 volts in series)

In the chart I posted it seems to show what I would consider normal data points the 10 amp can handle 15 amps along with the two 15 amps ones handling 15 amps. That all looks good to me. But then when you jump to the 10 20 48 one now it is showing on the same line 20 20 and 1amp. Which seems to say at 12 volts you can have 20 continuous current and if you double the the 12 to 24 you can still have 20 amps. But if you double the voltage to 48 you cut the continuous current by over 90 percent.

I am thinking that the continuous current is what the controller can output to the battery?
The only place where 'continuous current' is mentioned is in 'Max. continuous load current'. This refers to the load output current and not the battery output current. The maximum continuous battery current is given by 'Rated charge current'. This 'Rated charge current' is what gets used in the product name.
At the top of the chart is says the controller can handle 1160 watts and 20 amps at the 48 voltage.
Indeed.
On the surface it looks like I bought the right controllers (although the victron calculator that I just noticed recommends the 150 35? That seems to be unnecessary for these panels).
One or two 150/35?
On the side of the packaging it says max continuous current 1 amp. Sort of scared me.
Not sure what Victron puts exactly on their packaging, but in any case that 1 A should refer to the load output.
So are these controllers going to work?
Depends, the currents sound ok but I'm not sure about the voltages. On a cold winter day the voltages may be too high. What is the Voc and voltage temperature coeficient of your panels, and how cold can it get where you use them?
 
Each panel is 39-40V. So in total approx 80V.

With a 100V controller there is plenty of room. Average temp coefficient is approx 0.3%/C or so.

So at -10C (14F) its about 4V more for each panel (8V for the string, so it ends up at approx 88V). Still well within the 100V.

Unless the temp coefficient is way different, or you're in a really cold climate, it's unlikely you're going to hit the 100V mark.

But I agree, calculate on your specific situation and panels, don't assume.
 
You missed something. 48 version is to be used with a rely. That explains the 1 amp limit.

memaa.jpg
 
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What @Smokin said.

The 1 amp limit is to power a relay which can turn on/off any load your system is capable of handling.

The solar power to battery is 20 amps and completely separate from the load terminals.

I have two of these and they work fine but I’ve never had a use for the relay stuff so those terminals are empty.

Many of the Victron units are used in streetlight applications and the load terminals are often used for that.
 
If you don’t use the load output (battery bus bars for load) sounds like there’s no issues.
 
Thanks for responding. I have four panels that are rated 330 watts and the output voltage is 39-40. I planed on putting two in series for around 80 volts to each charge controller. But the panels put out 8 amps in bright sun and according to the data sheet that would blow out the 100/20 48.View attachment 69679
You're good, under 100v and rated charge current is 20a, max PV short circuit current is 20a. You will have 16a at around 80v.
 
Okay great you guys. And thanks Joe Ham and Smokin. I understand the concept of a controller relay that could be activated at certain parameters and the fact that there is a limit to the current draw of that relay. Makes sense.
The problem was I had no idea that there was a feature like that in the 48 volt model.

I think I have it now. If you buy the 10 or 15 amp 12/24 volt models you can directly connect you load to the load output on the Controller and they can handle switching on and off 15 amps.
If you buy the 20 amp model at 12 or 24 volts it can turn on and off the load up to a certain amount. The amount is guess work though.

If you read the datasheet before you buy it you get the impression that you can control up to 20 amps on either the 12 or 24 volt model.

But when you buy the controller the box does not say that. The box says 20 amps for the 12v and 10 amps for the 24 v model.

That's half of what you were led to believe looking at the data sheet. Oh well not a big deal.

20211021_165859.jpgIf how ever you buy the 48 volt model you will need an external relay to control the output feature.

Super clear now. Thanks for helping me out on this. I will probably not ever need or use this feature so a nothing burger for me.
 
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