MPPT controller and fuses

[philiph]

Hi guys,

Can any one give me advice on the following. We are in South Africa and voltage is 240V.

I have read on a site, cant find it again, but they were talking about an MPPT Charge Controller not requiring fuses between the panels and the controller. Is that correct? Can anyone give me advice?

I have an installation of 8 x 250W (Vmp 30.1V and Isc 8.83A) in parallel, 25A MPPT charge controller which is integrated in a 3KVA/2.4KW 24Vdc Inverter. Between the solar panels and controller is 12A fuses on each of the panels and 4mm sq solar cable. Between the controller and battery is 100A circuit breaker and 25mm sq cable. AC cable input to the inverter/charger is 32A circuit breaker and 4mm sq cable.

The question I have is, are the fuses correctly sized? Is the cable correctly sized? Do I need to install Circuit breaker between the battery and the inverter and what size? And most importantly, is the 25A charge controller big enough for 8 x 250W panels? Does anyone have experience in installing this type of inverter/charger and if so, how would you install an extra 2 x 25A MPPT charge controllers in parallel to the one in the inverter, if it is required?

Output from the inverter to the sub-db board will be for the client.

Well, thats my problem, look forward to receiving your comments.
Philip

[Sunking]

If this is in Africa there are no rules or regulations and you can do whatever you want, no one cares if you burn something up as there is no insurance or fire departments. In the USA electrical codes require you to use Over Current Protection Devices if 2 or more parallel strings are used. So if you keep it to a single string of panels no OCPD is required.

[philiph]

Hahaha there are some rules and regulations. Most importantly, I do not want my clients to fry. Then I would be sure to find out the rules and regulations.

[Naptown]

Hi guys,

Can any one give me advice on the following. We are in South Africa and voltage is 240V.

I have read on a site, cant find it again, but they were talking about an MPPT Charge Controller not requiring fuses between the panels and the controller. Is that correct? Can anyone give me advice?

I have an installation of 8 x 250W (Vmp 30.1V and Isc 8.83A) in parallel, 25A MPPT charge controller which is integrated in a 3KVA/2.4KW 24Vdc Inverter. Between the solar panels and controller is 12A fuses on each of the panels and 4mm sq solar cable. Between the controller and battery is 100A circuit breaker and 25mm sq cable. AC cable input to the inverter/charger is 32A circuit breaker and 4mm sq cable.

Fuse size is OK but why are you putting all panels in parallel. What is the voltage limit on the charge controller.

The question I have is, are the fuses correctly sized? Is the cable correctly sized? Do I need to install Circuit breaker between the battery and the inverter and what size? And most importantly, is the 25A charge controller big enough for 8 x 250W panels? Does anyone have experience in installing this type of inverter/charger and if so, how would you install an extra 2 x 25A MPPT charge controllers in parallel to the one in the inverter, if it is required?

Fuse size is adequate and absolutely fuses between battery and inverter and in addition between battery and charge controller. Both sides of the battery.

Output from the inverter to the sub-db board will be for the client.

Well, thats my problem, look forward to receiving your comments.
Philip

comments in red

[philiph]

Thanks for the response.

The charge controller specifications are:
MPPT operating voltage: 30 ~ 66Vdc
Voc: 75V
Nominal battery voltage: 24Vdc

That makes sense to me now, if I were to have 2 panels in series, how many could I then put in parallel before I overloaded the charge control? Would the MPPT controller regulate down to 24Vdc?

[Naptown]

Divide panel wattage by nominal battery voltage to determine required amps for CC
My suggestion would be to dump that one and install a good charge controller and switch the inverter
At 2000W it makes more sense to use a 48V system
So 2000W/24= 2 60 A charge controllers
2000W /48 = 1 45A charge controller

And actually with the questions you are asking you really shouldn't be doing this. This is basic Solar 101 and doing it professionally with having to ask questions like this tells me you do not have the knowledge to perform what you are being paid to do

[Sunking]

Phillip with 2000 watt input requires a minimum 40 Amp MPPT charge controller. You would be much better served if you used a quality MPPT controller with a minimum VOC input of 150 volts, and aim to run a panel voltage of 70 to 90 volts on a 48 volt battery system. Your 25 amp controller is a NO GO.

[philiph]

Thanks for your comments. I realise that I came across pretty much clueless, but was trying to talk in laymans terms and find out if there is anybody out there with experience with this type of inverter, sorry. What I needed to know has been answered.