@@sotasolar So, if each of the server rack batteries has an on/off switch and own internal breaker, would you not bother using Class-T fuses for each branch of the batteries (six batteries in three pairs) into a Lynx Power In and then use a single big Dihool 400 or 600 for in between the Lynx Power In and Distributors? I thought about using the Lynx Shunt, but seems like it (and it's expensive fuse) are not worth the extra when this is a good area to put the main system switch and just use regular Smart Shunt.
@@dalehollenbaugh6084 Server rack batteries have their own protection, so you're good, don't need a Class T The Dihool can actually interrupt more current than a class T... and is resettable.
I liked your pile of fried fuses and other equipment 🙂... typically fusing, particularly DIY fusing, both uses the wrong type of fuse and the wrong current ratings. But I've seen horrible errors made even on professional installations. Problems that I saw: * Improper use of paralleling connectors on the roof. Fire hazard. Paralleling should always be done through a combiner box. Never use MC4 paralleling connectors. Ever. * Improper fusing of paralleled solar panels. Each individual string needs its own fuse before being paralleled (hence why you use a proper combiner box). The whole point is to prevent the other paralleled panels from dumping into a shorted panel (causing a fire). Fire hazard. * Situating a fuse at the "solar" input of a charge controller is completely worthless. It protects nothing. Solar panel fusing should be done in the combiner box, relatively close to the panels (but can still be off the roof). * Improper use of auto blade fuse. A solar ceramic fuse must be used on the solar panel power path (before the charge controller) (typically a 10x38 in a DIN-mounted fuse holder). Never use auto blade or glass fuses anywhere in a solar system's major power electronics paths. Ever. The only use case is in final distribution, and then only for low-voltage (12V) gear. * Charge controller BAT output must be fused or have a breaker (it might be but I couldn't tell right off-hand. Smaller Victron charge controllers do have built-in fuses for 12/24V systems but the larger ones require external fusing on the BAT side. Otherwise it's a fire-hazard if the charge controller has failure/short because the relatively thinner wire can cause a fire without tripping main battery breakers or the main battery fuse. MCBs and MCCBs (mini circuit breakers) have two trip mechanisms. One is a bimetalic strip that does indeed heat up (since that is how it operates), though breakers generally have no problem dissipating the heat under normal operation. The bimetalic strip handles normal over-current trips. The second mechanism is a solenoid which handles instant trips when the current exceeds 5x (Type C) or 3x (Type B) the rating... that one handles direct shorts. UNPOLARIZED DC MCB or MCCBs must be used in solar systems. The only exception is that the DC MCB in the combiner box can be polarized. All other MCBs must be unpolarized (be able to trip safely with current flowing in either direction). All breakers in solar power systems must be 2-pole, breaking on both the positive and the negative. In anycase, that's what I saw that was wrong / fire-hazard / or possibly-wrong on that RV during the video. -Matt
Great input , thank you. It’s my understanding that fusing is only required when the max PV amps of an array can exceed the max series fuse rating. For most of our systems we stay under that (15 a) and when we don’t, we fuse each string.
@@sotasolar Yes and no. Yes in that theoretically a solar panel can tolerate a short-circuit current up to its maximum fuse rating before catching on fire. But, no, you can't depend on that as a reason to eliminate fusing or use a paralleling MC4 connector. I'll give you a quick list of the problems: * A MC4 connector failure up on the roof can catch the roof on fire. So, for example, when the retention tabs that hold the connector together get brittle with age (doubly so if exposed to the sun) and begin breaking. This is the main reason why you should never do any combining up on the roof. * MC4 paralleling connectors have extremely variable levels of manufacturing quality and often have insufficient metal busses inside to actually parallel their rating without melting. * Solar panel voltages, particularly in strings (2 or more panels in series), make ARC shorts very dangerous (very hot). Even a single-panel string can develop high voltages in very bright and/or very cold conditions (exceeding the label). (This is also why solar ceramic fuses must be used on solar-panel wiring, never auto blade or glass fuses). * ARC shorts basically happen at MC4 connector interfaces, disconnect switch interfaces, inside non-spring-loaded disconnect switches, at fuse interfaces, and inside fuses. (this is also why you don't want to put fusing up on the roof either). * The combiner box provides additional levels of safety, including a better air-gap and more resilience against charring from a failed component inside getting outside the box. (just like plug and switch housings do for home wiring). -- That's it in a nutshell. Best practices are thus to bring the individual string cabling down off the roof and into a bay and situate the combiner box in the bay where it is protected from the elements and easily accessible. The combiner box contains the solar fuses, a master breaker (a convenient disconnect point), and typically surge protection as well. -Matt
My favorite DOG channel
The side plot we never knew we needed. Glad you’re here for it!
What are the breakers you are using?
500 amp fuse on that last one...WOW!!!!
What’s the link to those knobs?
So, are you only using the big Dihool breaker as a main power switch and not actually relying on it as a breaker?
Yes, as a breaker as well. We call that a Two-Fer (two for one)
@@sotasolar So, if each of the server rack batteries has an on/off switch and own internal breaker, would you not bother using Class-T fuses for each branch of the batteries (six batteries in three pairs) into a Lynx Power In and then use a single big Dihool 400 or 600 for in between the Lynx Power In and Distributors? I thought about using the Lynx Shunt, but seems like it (and it's expensive fuse) are not worth the extra when this is a good area to put the main system switch and just use regular Smart Shunt.
@@dalehollenbaugh6084 Server rack batteries have their own protection, so you're good, don't need a Class T The Dihool can actually interrupt more current than a class T... and is resettable.
Can you show us how to build a good Scalfolding?
I need to build a good one first. Actually this is my second. It is better, but could be improved.
I liked your pile of fried fuses and other equipment 🙂... typically fusing, particularly DIY fusing, both uses the wrong type of fuse and the wrong current ratings. But I've seen horrible errors made even on professional installations.
Problems that I saw:
* Improper use of paralleling connectors on the roof. Fire hazard. Paralleling should always be done through a combiner box. Never use MC4 paralleling connectors. Ever.
* Improper fusing of paralleled solar panels. Each individual string needs its own fuse before being paralleled (hence why you use a proper combiner box). The whole point is to prevent the other paralleled panels from dumping into a shorted panel (causing a fire). Fire hazard.
* Situating a fuse at the "solar" input of a charge controller is completely worthless. It protects nothing. Solar panel fusing should be done in the combiner box, relatively close to the panels (but can still be off the roof).
* Improper use of auto blade fuse. A solar ceramic fuse must be used on the solar panel power path (before the charge controller) (typically a 10x38 in a DIN-mounted fuse holder). Never use auto blade or glass fuses anywhere in a solar system's major power electronics paths. Ever. The only use case is in final distribution, and then only for low-voltage (12V) gear.
* Charge controller BAT output must be fused or have a breaker (it might be but I couldn't tell right off-hand. Smaller Victron charge controllers do have built-in fuses for 12/24V systems but the larger ones require external fusing on the BAT side. Otherwise it's a fire-hazard if the charge controller has failure/short because the relatively thinner wire can cause a fire without tripping main battery breakers or the main battery fuse.
MCBs and MCCBs (mini circuit breakers) have two trip mechanisms. One is a bimetalic strip that does indeed heat up (since that is how it operates), though breakers generally have no problem dissipating the heat under normal operation. The bimetalic strip handles normal over-current trips. The second mechanism is a solenoid which handles instant trips when the current exceeds 5x (Type C) or 3x (Type B) the rating... that one handles direct shorts.
UNPOLARIZED DC MCB or MCCBs must be used in solar systems. The only exception is that the DC MCB in the combiner box can be polarized. All other MCBs must be unpolarized (be able to trip safely with current flowing in either direction). All breakers in solar power systems must be 2-pole, breaking on both the positive and the negative.
In anycase, that's what I saw that was wrong / fire-hazard / or possibly-wrong on that RV during the video.
-Matt
Great input , thank you.
It’s my understanding that fusing is only required when the max PV amps of an array can exceed the max series fuse rating. For most of our systems we stay under that (15 a) and when we don’t, we fuse each string.
@@sotasolar Yes and no. Yes in that theoretically a solar panel can tolerate a short-circuit current up to its maximum fuse rating before catching on fire. But, no, you can't depend on that as a reason to eliminate fusing or use a paralleling MC4 connector.
I'll give you a quick list of the problems:
* A MC4 connector failure up on the roof can catch the roof on fire. So, for example, when the retention tabs that hold the connector together get brittle with age (doubly so if exposed to the sun) and begin breaking.
This is the main reason why you should never do any combining up on the roof.
* MC4 paralleling connectors have extremely variable levels of manufacturing quality and often have insufficient metal busses inside to actually parallel their rating without melting.
* Solar panel voltages, particularly in strings (2 or more panels in series), make ARC shorts very dangerous (very hot). Even a single-panel string can develop high voltages in very bright and/or very cold conditions (exceeding the label).
(This is also why solar ceramic fuses must be used on solar-panel wiring, never auto blade or glass fuses).
* ARC shorts basically happen at MC4 connector interfaces, disconnect switch interfaces, inside non-spring-loaded disconnect switches, at fuse interfaces, and inside fuses.
(this is also why you don't want to put fusing up on the roof either).
* The combiner box provides additional levels of safety, including a better air-gap and more resilience against charring from a failed component inside getting outside the box.
(just like plug and switch housings do for home wiring).
--
That's it in a nutshell. Best practices are thus to bring the individual string cabling down off the roof and into a bay and situate the combiner box in the bay where it is protected from the elements and easily accessible.
The combiner box contains the solar fuses, a master breaker (a convenient disconnect point), and typically surge protection as well.
-Matt
Cecropia moth