Dear Members of Power forum SA

i need your assistance with regards to caculation of fuse and breaker placement between the Batteries and inverter.

Also i would like to know what the maximum allowable amperage (current ) can be drawn by the inverter from the battery side.

I have installed 3 x 350w solarpanels in series , with a 5kw pure sinewave inverter (MKS 5) 

i would like to protect the inverter and batteries against fire.

 

What is the max DC current, as printed on the label? Get a fuse as close to that value, but on the higher end of the scale. i.e. if they say 105A, get a 125A fuse. 

Hi,

Thanks for the response.

what's the reason to go higher. My take to be safe one should go lower.

The booklet says maximum amperage should be 135amps

Awaiting your response. 

Thanks, Vee 

5 hours ago, Veejay said:

Hi,

Thanks for the response.

what's the reason to go higher. My take to be safe one should go lower.

The booklet says maximum amperage should be 135amps

Awaiting your response. 

Thanks, Vee 

DC current can sometimes go higher than the max rating, due to startup currents. A 25% higher fuse will help to avoid nuisance blows

Thank you, 

The manual states maximum amperage 135 should stick that or go higher. 

Also is there a way to calculate the maximum amperage draw from the dc-battery  side by the inverter. 

The minimum recommended battery is 100amp/hr is it safe to start with 4 x 48v 60amp hr batteries,. 

Thanking you for your assistance. 

Regards, 

Vee 

Roughly Power in = Power out.

Vdc*Idc (in) = Vac*Iac plus say 5%(out).

4 hours ago, Veejay said:

The minimum recommended battery is 100amp/hr is it safe to start with 4 x 48v 60amp hr batteries,. 

You'll probably get away with it, as long as you keep the load under 50% of rated power, and you set the maximum charge current low enough, which would have to be 10 A (usually setting 02).

Thanks guys, 

The current amperage will be around 9amps as I have 3 x 350w panels in series so the amperage should remain constant. 

With regards to the breaker and fuse between inverter and batteries the user manual suggests 135amps maximum, should I use a 135amp fuse & breaker or should I give an allowance of +25% or should I go less than 135amps 

Remember that this is just to get the system running but I need to allow to expand this system, with more panels and increasing the battery bank size Soon after. 

Thanking you'll

Awaiting your response. 

Help Required Urgently:

please find attached specs for my5kw inverter :

advise needed from solar experts on breaker and fuse to be used :

 1.] between batterey & inverter.  2.] Ac input to inverter  3.] AC output from inverter.   

 4.] Solar panels to inverter. (solar panels = 1 string of 3 x 350w panels in series.) 

thanks awaiting your response.

regards,

Vee

Just now, Veejay said:

Help Required Urgently:

please find attached specs for my5kw inverter :

advise needed from solar experts on breaker and fuse to be used :

 1.] between batterey & inverter.  2.] Ac input to inverter  3.] AC output from inverter.   

 4.] Solar panels to inverter. (solar panels = 1 string of 3 x 350w panels in series.) 

thanks awaiting your response.

regards,

Vee

 

4 hours ago, Veejay said:

1.] between batterey & inverter. 

Presuming at least 35 mm² cable, 100 A or 125 A, DC rated. Occasional surges of 200 A to start motors won't bother them.

> 2.] Ac input to inverter

Presuming 6 mm² cable, 40 A, perhaps 32 A. 

>3.] AC output from inverter.

Presuming 4 mm² cable, 25 A or 32 A. 

> 4.] Solar panels to inverter. (solar panels = 1 string of 3 x 350w panels in series.) 

10 or 12 A, DC rated, preferably proper PV fuses. [ Edit : or suitable DC rated breakers, like Noark brand. ] 

The protection is sized for the cable, hence the presumptuous.

Edited April 12, 20197 yr by Coulomb

9 hours ago, Coulomb said:

Presuming at least 35 mm² cable, 100 A or 125 A, DC rated. Occasional surges of 200 A to start motors won't bother them.

> 2.] Ac input to inverter

Presuming 6 mm² cable, 40 A, perhaps 32 A. 

>3.] AC output from inverter.

Presuming 4 mm² cable, 25 A or 32 A. 

> 4.] Solar panels to inverter. (solar panels = 1 string of 3 x 350w panels in series.) 

10 or 12 A, DC rated, preferably proper PV fuses. [ Edit : or suitable DC rated breakers, like Noark brand. ] 

The protection is sized for the cable, hence the presumptuous.

Thanks coulomb, 

Great stuff, I was thinking on the same line, thanks for the confirmation. 

Regards, 

Vee 

1 minute ago, Veejay said:

Thanks coulomb, 

Great stuff, I was thinking on the same line, thanks for the confirmation. 

Regards, 

Vee 

Hi, who carries the noarc breakers and fuses. 

I'm an ocean and continent away from you, so I'll leave that to the locals.

8 hours ago, Veejay said:

Hi, who carries the noarc breakers and fuses. 

Hi I got mine from sonop solar online store