diy solar

diy solar

Can panels overpower charge controller?

M

mrevesz

New Member
Joined
Oct 13, 2019
Messages
31
I have 4 24volt nominal 305watt panels
I am curious what happens if I connect 2series 3parallel to a charge controller rated for 100volts and 50amps?


with 2 of these panels in series that's around 80volts open circuit. Well below 100v of the charge controller.
Under ideal conditions I get 1830 watts from 6 panels.
When the charge controller converts 1830 watts to 24V to charge my battery, it could potentially create 76 amps of current. Will this damage or destroy the charge controller?

What I am hoping is that I can gain more power on cloudy days and when in full sun the extra power will just be lost(but not destroy my charge controller)
This is theoretical in case I want to upgrade slightly in the future without the expense of a new charge controller. Simply adding 2 more panels to the 4 I have to go from 1220 to 1830 watts is a cheaper way to get a boost than to have to invest in higher voltage battery bank or buy additional charge controllers

Is this safe?
I guess I should add that I am using a Victron BlueSolar 100/50, so the quality should be pretty good.
 
Most likely it will damage it. Best case scenario the SCC can turn its self off but Im not sure if they work this way.
I use multiple SCC's and actually dont go over 75% of their rating just to help keep them cool. I know this is probably too conservative but I would rather not be stuck with a broken controller and no power waiting for a new one. Plus the extra controllers add a bit of redundancy.
 
Last edited:
  • Like
Reactions: JPC
You should keep within the specifications of the charge controller, you can find them here
In it you can read the following:
Max. PV short circuit current 60A ²
² A PV array with a higher sort circuit current may damage the controller

This is the short circuit current of the panels, this is not the 50A charge rating @ 24V, do not mix these up when trying to figure out what to connect.
The victron also has a charge limit of 1400watt, so in full sun your panels will not get maxed out.
 
Yes but almost all inverters have a surge rating that is 2x "continuous" power. What no one has decided here that I know of is the inverter storing that extra energy in its capacitors or is it pulling from batteries
burtinator said:
You should keep within the specifications of the charge controller, you can find them here
In it you can read the following:
Max. PV short circuit current 60A ²
² A PV array with a higher sort circuit current may damage the controller

This is the short circuit current of the panels, this is not the 50A charge rating @ 24V, do not mix these up when trying to figure out what to connect.
The victron also has a charge limit of 1400watt, so in full sun your panels will not get maxed out.
Click to expand...
Is not 1800 greater than 1400. So how is this ok what am I missing?
 
Craig said:
Yes but almost all inverters have a surge rating that is 2x "continuous" power. What no one has decided here that I know of is the inverter storing that extra energy in its capacitors or is it pulling from batteries

Is not 1800 greater than 1400. So how is this ok what am I missing?
Click to expand...
Inverter surge rating is based on the inductors storage. LF models have huge inductors, LF models have capacitor banks and small inductors.
Battery demand shouldnt be affected.
 
mrevesz said:
I have 4 24volt nominal 305watt panels
I am curious what happens if I connect 2series 3parallel to a charge controller rated for 100volts and 50amps?


with 2 of these panels in series that's around 80volts open circuit. Well below 100v of the charge controller.
Under ideal conditions I get 1830 watts from 6 panels.
When the charge controller converts 1830 watts to 24V to charge my battery, it could potentially create 76 amps of current. Will this damage or destroy the charge controller?

What I am hoping is that I can gain more power on cloudy days and when in full sun the extra power will just be lost(but not destroy my charge controller)
This is theoretical in case I want to upgrade slightly in the future without the expense of a new charge controller. Simply adding 2 more panels to the 4 I have to go from 1220 to 1830 watts is a cheaper way to get a boost than to have to invest in higher voltage battery bank or buy additional charge controllers

Is this safe?
I guess I should add that I am using a Victron BlueSolar 100/50, so the quality should be pretty good.
Click to expand...
A CC has two limiting parameters...
You should not exceed EITHER one, but the voltage limit will destroy the CC the watts limit based on voltage should shunt down production.
Be certain the combined MAXIMUM POSSIBLE VOLTAGE does not exceed the cc rating.
That means the open circuit voltage combined cannot exceed the rated input voltage of the cc.
 
Craig said:
Yes but almost all inverters have a surge rating that is 2x "continuous" power. What no one has decided here that I know of is the inverter storing that extra energy in its capacitors or is it pulling from batteries

Is not 1800 greater than 1400. So how is this ok what am I missing?
Click to expand...

I'm not 100% certain on this just going on what burtinator was saying but...
My CC is rated for 60amps max short circuit current. If I put 6 9.9amp panels in parallel I get 59.4 amps(pushing it pretty close).

Yes I will technically have 1830watts of panels, but the charge controller will only deliver 1400watts to my batteries in those ideal conditions. 99% of the time I will be getting less than 1400 watts from the panels(due to sun angle, panel orientation, cloud, temperature, dust, etc.) so it isn't really a waste to have the extra panels.

For my 4 panels I will likely go parallel. If I have 6 panels I will do 2series 3 parallel and this will give me 96volts(corrected for maximum peak open voltage during extremely cold weather), and about 30 amps. I should also be able to get away with doing all 6 in parallel as this would give me even less volts and push me up to that limit of 60 amps.

So I would be pushing the equipment pretty hard but it should all work if I understand this correctly.
The only way I should be able to over voltage my CC is if I were to connect the panels 3 or 4 in series and that would destroy the CC.
 
Ok disregard anything posted in this thread about inverters and surge rating. That was for another thread and I have no idea how it got posted here.


But here is the bottom line I'm afraid if you send 1800 watts to a 1400 watt inverter it will fry. Will has videos demonstrating that under Ideal circumstances the panels could excede their listed output. I don't think it matters how the panel gets its watts by being 10 amps and 30 volts or 10 volts and 30 amps. It's somewhat irrelevant to SCC watts are watts no matter how they are created. So again I'm afraid that extra energy may fry your SCC. I do think though that your quality inverter may have some wiggle room .

I'm willing to be wrong here I just need to know why I'm wrong
 
It comes down to the device really. The voltage is the hard limit. There'll be a safety margin in there somewhere, but exceeding the voltage rating on the PV input is a quick path to destroying the transistors in the device, so don't ever do that.

Current is another story. Several SCCs will limit the current to protect themselves. Victron does, and I'm pretty sure I've read specs with at least some epever SCCs where they do it too, but needless to say, check specs before purchase. No doubt Victron's solar inverter / chargers do the same, and I'm sure so do other reputable brands. At least one epever I read the specs on recently, for another thread, could actually disconnect the PV on overvoltage, so that's nice.

The MPPs seem to throw an alarm, so not sure how they would actually handle since they are aware (if a brick can be aware!) of their limits but will they shutdown the PV input on over current or will they catch fire? I can't answer that question.
 
Just as mrevesz said, the controller will just take 1400watt, even if you could take 1800 watt out of the panels.
As long as the open circuit voltage and the short circuit current stay within the specs of the charge controller it doesnt matter if the wattage of the solar panels are larger than what the controller will use to charge the batteries. You will just lose the 400watt of potential energy.
Imho this isnt that big of problem, because most of the time you won't get the full rated power of the panels anyways. (because of clouds, angle to the sun, etc)
 
Ok now I get it the charger can take in a maximum of 6000 watts but only charge 1400 watts guess I should of actually read the specs instead of going off the charge wattage. Learn something new every day. Thank You.
 
mrevesz said:
I have 4 24volt nominal 305watt panels
I am curious what happens if I connect 2series 3parallel to a charge controller rated for 100volts and 50amps?


with 2 of these panels in series that's around 80volts open circuit. Well below 100v of the charge controller.
Under ideal conditions I get 1830 watts from 6 panels.
When the charge controller converts 1830 watts to 24V to charge my battery, it could potentially create 76 amps of current. Will this damage or destroy the charge controller?

What I am hoping is that I can gain more power on cloudy days and when in full sun the extra power will just be lost(but not destroy my charge controller)
This is theoretical in case I want to upgrade slightly in the future without the expense of a new charge controller. Simply adding 2 more panels to the 4 I have to go from 1220 to 1830 watts is a cheaper way to get a boost than to have to invest in higher voltage battery bank or buy additional charge controllers

Is this safe?
I guess I should add that I am using a Victron BlueSolar 100/50, so the quality should be pretty good.
Click to expand...

Craig said:
Ok now I get it the charger can take in a maximum of 6000 watts but only charge 1400 watts guess I should of actually read the specs instead of going off the charge wattage. Learn something new every day. Thank You.
Click to expand...


I don’t see where you are getting 6000watts from?
 

Attachments

  • 5D18FEB2-5B16-4D5F-AAD6-B75430E62431.png
    5D18FEB2-5B16-4D5F-AAD6-B75430E62431.png
    203.5 KB · Views: 7
Craig said:
Max PV voltage times max PV amps
Click to expand...
Ahh, you used math.

100v max PV input voltage to the primary mppt, but NOWHERE NEAR 60 amps... likely around 14 or so amps...
max PV amperage is short circuit amps, which would draw the volts down around 15...
 
Why not 60 amps it says max PV short circuit current 60 amps so as long as you don't go over 100 volts and 60 shirt circuit amps you can feed it up to 6000 watts and it would just waste 4600 watts or there abouts. What am I missing.
 
The parameters are stated to show each end of the production the CC is rated to handle.

60amps max isn’t at the max voltage... yes, if you fed it 6000watts, it would shunt 4600 of it... as long as the panels max voltage wasn’t over 100v...
the cc wattage number that matters is the 1400... max PV into the 24v battery bank. So, ideally, to get max usage from the PV, keep the voltage MAXIMUM POSSIBLE under the cc rating, and make sure the added short circuit amps of your array is under 60amps.
 
Think of it as transformer safety ratings... output max is 60 amps, input max is 100v...
 
I'm curious now what would happen if I connected for example 10kW of panels to the charge controller(for the sake of argument).
If the panels are connected in parallel at 24V nominal. Would the CC just make use of 1400 watts and not allow any more energy to pass?
Or would the transformer inside the MPPT just act like a short circuit and all 10kW would burn through it and set it on fire?
 
I would not recommend the experiment.

Best is to size the array production a bit over max wattage, to get the most out of your solar investment bucks, and have more controllers if you have more panels.
 
You must log in or register to reply here.

Similar threads

N
Pwm vs MPPT charge controller on a small scale
Replies
15
Views
929
iwasforcedtopickausername
I
W
Will Solar charge controller work.
Replies
6
Views
276
Rednecktek
Rednecktek
N
Maximum Controller Capacity
Replies
4
Views
135
NewbySolarGuy
N
W
RENOGY 100AMP charge controller HELP
Replies
1
Views
110
Nobodybusiness
Nobodybusiness
S
EG4-6000xp (or other) Solar charge controller recover from battery shutdown
Replies
10
Views
565
Samsonite801
S
Back
Top