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diy solar

diy solar

Lifepo4 fuses/terminal fuses

I don't have a 225a to meassure. They will be between these values. The datasheet should list the

200a 0.39 milliohms
300a 0.22 milliohms

Just multiple your current to get the watts.
 
this is how i installed the fuses
225A class-t fuses are on the way from germany.
I don't have a 225a to meassure. They will be between these values. The datasheet should list the

200a 0.39 milliohms
300a 0.22 milliohms

Just multiple your current to get the watts.
this is how i installed the fuses
225A class-t fuses are on the way from germany.
 

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That looks good - but toss the little round caps - they are flamable and in the batttery manual it typically says to toss them as the first step to hook the batteries up.

get something like this for the ends of the cables to cover the bolts and the like. They come in 3 sizes depending on the wire gauge



And if that tank below is something flamable - store it someplace else or store the batteries someplace else.
 
That looks good - but toss the little round caps - they are flamable and in the batttery manual it typically says to toss them as the first step to hook the batteries up.

get something like this for the ends of the cables to cover the bolts and the like. They come in 3 sizes depending on the wire gauge



And if that tank below is something flamable - store it someplace else or store the batteries someplace else.
Yes i know. They are not ready yet. I will cover them. They are now in my own garage in winter storage. I'm only getting them ready for summer. I will cover the battery terminals somehow and bussbars with heat shrink.
 
That looks good - but toss the little round caps - they are flamable and in the batttery manual it typically says to toss them as the first step to hook the batteries up.

get something like this for the ends of the cables to cover the bolts and the like. They come in 3 sizes depending on the wire gauge



And if that tank below is something flamable - store it someplace else or store the batteries someplace else.
And thank you for all your help. You told me all i need to know. I will do as you told me. This is my system.
 

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Looks good - the only thing I see that might be questionable is the DC breakers in plastic housings.... If they are polarized and not hooked up right they can burst into flames after they are turned off... i.e.. arcs.... also - depends on the brands of those and the source - there have been more than a few teardown videos where when they open it up, it is a copper braid, solder blob and a spring - no arc chutes or anything useful in the guts...

If they are UL or CE listed you should be fine. If one of those is across the PV lines coming in I would change it out for a IMO disconnect - Because PV panels are ALWAYS producing when the sun is out you need to make sure the disconnect is wide enough that an arc can't form. The IMO disconnects are spring loaded knife switches in a self-extenguishing plastic housing.... meaning if there is enough heat it will melt and bubble, but when the heat goes away if there were flames they go out.
 
Ok. Thanks. Pv wires have ceramic disconnect fuses. I was planning to replace them with nh disconnect fuses,but maybe imo is better? You don't think i need fuses in pv lines?they are 4x410w 2s2p. So voltage is about 75v and max 28A. Dc loads are very small. Couple of led lights and fuse is 10A. Other 2 of them is for 12v fridge with 16A fuse,and diesel heater 16A fuse. They are ce listed dc fuses,but they are from aliexpress.they have been working fine. Lynx power in is fused and there are 400A multiplus megafuse,125A mppt megafuse and 40A megafuse for dc wire and all other small 12v line fuses for modem,cerbo and cooling fans.
 
You only need to fuse the PV wires if there are more than 2 strings in parallel. Your PV wires need to be sized for 156% of expected current. That is expected current * 1.25 * 1.25... then even if there is a short the wires won't melt. All PV wires in or on a dwelling must be inside metal conduit.

The IMO disconnect is designed to break the connections to the pv array and extinguish any arc... it has a spring and snap that makes and breaks the connection in 1ms typically. The separation inside is just over 1 inch and the bar is hardened plating so it won't be damaged when cycling.
 
You only need to fuse the PV wires if there are more than 2 strings in parallel. Your PV wires need to be sized for 156% of expected current. That is expected current * 1.25 * 1.25... then even if there is a short the wires won't melt. All PV wires in or on a dwelling must be inside metal conduit.

The IMO disconnect is designed to break the connections to the pv array and extinguish any arc... it has a spring and snap that makes and breaks the connection in 1ms typically. The separation inside is just over 1 inch and the bar is hardened plating so it won't be damaged when cycling.
In pv lines now i have these fuses. So you don't think they are good? I only find disconnect safe switch here in Finland and i'm not sure they are same as those imo disconnectors. I want to do all right this time. They are like this.
 
In pv lines now i have these fuses. So you don't think they are good? I only find disconnect safe switch here in Finland and i'm not sure they are same as those imo disconnectors. I want to do all right this time. They are like this.

All of those specs look like the IMO brand so it is probably good.

It doesn't hurt to fuse both positive and negative wires - it just isn't required and the fuses can NOT be used as a disconnect - opening those fuses while current is flowing can damage the ends of them.
 
All of those specs look like the IMO brand so it is probably good.

It doesn't hurt to fuse both positive and negative wires - it just isn't required and the fuses can NOT be used as a disconnect - opening those fuses while current is flowing can damage the ends of them.
Ok thank you again. You really know these things👍 i will buy that disconnector and throw fuses away. Can you tell me also should i buy 2p or 4p disconnect? I have 2 series of 410wp panels parallel. One panel voc is 37.40 and isc 13.88A. I was planning to wire both strings with own wires. So 2+2 6mm2.
 
the 4p is for two independant strings - just make sure the voltage and current is covered .... the current at 156% of expected... the voltage just allow around 20%
 
the 4p is for two independant strings - just make sure the voltage and current is covered .... the current at 156% of expected... the voltage just allow around 20%
So if i have 2 strings parallel and they both have 2 panels in series isc 13.88A and i wire them both own 2x6mm2 wires to disconnect switch (2+2) and from there to charge controller. So it is 43A switch that i need? And do i need 2p or 4p model? Does those imo disconnectors switch off if there is shorcut in wire or panel, or does they only do it manually? Seems to be hard to find over 32A switch here,but maybe it is big enough for so small system?
 
The 4p model has 4 connectors on it (they wire diagonal across so verify the wiring diagram when hooking it up)

So a 4p switch would disconnect 4 wires - or the pos and neg from 2 strings

panels - in series the current stays the same and voltage adds. In parallel the current adds and the voltage stays the same.

So 2s is 13.88amps... then you connect those to 1 circuit of the disconnect - and the other 2s connects to the other circuit of the disconnect. Then inside they connect to independant MPPT inputs.

If you have two series strings and they are connected in parallel to only 1 MPPT then you can just use the 2p model with a total current rating of the next size over 28amps...
 
The 4p model has 4 connectors on it (they wire diagonal across so verify the wiring diagram when hooking it up)

So a 4p switch would disconnect 4 wires - or the pos and neg from 2 strings

panels - in series the current stays the same and voltage adds. In parallel the current adds and the voltage stays the same.

So 2s is 13.88amps... then you connect those to 1 circuit of the disconnect - and the other 2s connects to the other circuit of the disconnect. Then inside they connect to independant MPPT inputs.

If you have two series strings and they are connected in parallel to only 1 MPPT then you can just use the 2p model with a total current rating of the next size over 28amps...
Ok thanks. Yes i have two series strings connected parallel. My plan was wire them both with own 2x6mm2 wires and make that parallel connection in that switch. Because now i have only those 2x6mm2 wires and distance is about 15 meters one direction so 2x15 meters. I think they are now not enough? Now they are connected parallel in the roof.
 
So, one MPPT in the end - so I would bring the wires into the 2P disconnect and combine them right there... and on the output there would be one set of wires out.
 

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