Hi guys,

I installed the attached system to have lights in my house during Load Shedding. 

Where do I need to place fuses and what size fuses would I need?  Currently I have NO fuses in the system. Just added them to the drawing, but not sure if they can go there. 

Another issue I have is that the first few LED modules closest to the Battery / solar regulator is very bright, but further down the line the brightness drops down significantly. 

I used normal white flat twin flex from the Dimmer Control unit. Me thinking the twin flex is too thin. 

I'm no expert in this field so please bare with me. 

Regards 

 

The fuse is there to protect the cable (so that a short circuit does not overheat the cable and set the house on fire). Where you put them in the picture is fine. You don't need one for a single string of PV (or a single panel), and you have one in the battery + line as well as in the load + line. The one after the dimmer-unit is probably not required, it is already protected by the one before it.

@plonkster thanks alot. 

Any recommendation on size of fuse? 

 

Edited March 18, 20196 yr by Peyper

53 minutes ago, Peyper said:

@plonkster thanks alot. 

Any recommendation on size of fuse? 

 

That would be determined by the size of your cable , assuming the cable has been sized correctly for the load ....

In you case probably a 25 A on the battery and a 5 A on the lights (check that cables are rated for at least that)

8 minutes ago, Jaws said:

That would be determined by the size of your cable , assuming the cable has been sized correctly for the load ....

Hi Jaws, 

I think all the cabling is sufficient up to the Dimmer.  The only worry I have is the extremely thin Twin flex used from the dimmer all the way throughout the 31 Led modules. 

They do loose brightness the further they are from the battery / solar regulator 

10 minutes ago, Peyper said:

Hi Jaws, 

I think all the cabling is sufficient up to the Dimmer.  The only worry I have is the extremely thin Twin flex used from the dimmer all the way throughout the 31 Led modules. 

They do loose brightness the further they are from the battery / solar regulator 

That would be due to the resistance of the cable causing a voltage drop.

 

What is the distance to the last LED ?

 

I would recommend that you get a bigger cable to minimise the voltdrop as this would also make your installation more effiecent.  The 5 A fuse will still work

31 x 1.5 = 46.5 W

46.5 W / 12 V = 3.9 A

1 hour ago, Jaws said:

That would be determined by the size of your cable , assuming the cable has been sized correctly for the load ....

What he said ^^^ 🙂

This is a mantra that you have to repeat a few times: The fuse is there to protect the cable, and by extension, to prevent a fire because said cable overheated. If ever in doubt, size the fuse for the cable. The cable should of course already be sized to the load, and because copper is expensive nobody puts too thick a cable on a small load, so in the end it will all work out 🙂

2 hours ago, Jaws said:

That would be due to the resistance of the cable causing a voltage drop.

 

What is the distance to the last LED ?

 

I would recommend that you get a bigger cable to minimise the voltdrop as this would also make your installation more effiecent.  The 5 A fuse will still work

31 x 1.5 = 46.5 W

46.5 W / 12 V = 3.9 A

Easily around 50 metres. Its obviously not a straight line. The cable lies looped etc. 

Sounds like the cable, 50m is a long way for 12V. Is there any way to make the cable into a complete loop, so you effectively double the cable thickness to the furthest point.

Edited March 18, 20196 yr by DeepBass9

2 hours ago, DeepBass9 said:

Sounds like the cable, 50m is a long way for 12V. Is there any way to make the cable into a complete loop, so you effectively double the cable thickness to the furthest point.

I will definitely try this and all other options once I am back home. 

Thanks guys 

7 hours ago, Peyper said:

Hi Jaws, 

I think all the cabling is sufficient up to the Dimmer.  The only worry I have is the extremely thin Twin flex used from the dimmer all the way throughout the 31 Led modules. 

They do loose brightness the further they are from the battery / solar regulator 

You could feed it as a ring from both ends - would probably help to even up the brightness.  But with low voltage / hgh current you do need to use thicker wire.

1 hour ago, Elbow said:

You could feed it as a ring from both ends - would probably help to even up the brightness.  But with low voltage / hgh current you do need to use thicker wire.

Thanks