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diy solar

Is my set up safe?

Can you find a 250A breaker from a reputable brand for a price you can stomach? Most reputable brands don't produce breakers above 200A, many chinese off brands claim higher ratings but people say they are not reliable (which for a circuit breaker is a big deal). Outback, Xantrex and Midnite solar all make panel mount 250A breakers but they cost roughly $100. Waytek Wire--which is a reputable (US) seller--has one or two options that might be more affordable, but I don't know anything about the brands.
 
Dzl said:
Can you find a 250A breaker from a reputable brand for a price you can stomach? Most reputable brands don't produce breakers above 200A, many chinese off brands claim higher ratings but people say they are not reliable (which for a circuit breaker is a big deal). Outback, Xantrex and Midnite solar all make panel mount 250A breakers but they cost roughly $100. Waytek Wire--which is a reputable (US) seller--has one or two options that might be more affordable, but I don't know anything about the brands.
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Hi Dzl,
im not sure of the quality of the 250A unit i sourced, but it had reasonable review ratings, but of course that dont go for much.

This is what i was thinking of using....

Car Audio Circuit Breaker DC12V-42V Manual Reset Car Stereo Audio Inline Circuit Breaker (250A) : Amazon.co.uk: Business, Industry & Science

Car Audio Circuit Breaker DC12V-42V Manual Reset Car Stereo Audio Inline Circuit Breaker (250A) : Amazon.co.uk: Business, Industry & Science
www.amazon.co.uk
 
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Personally, I don't have experience with that breaker, but I would avoid it, it looks like one of the many off brands copying Bussmann breakers. If the reputable brands can't or don't make a breaker above 150-200A in that form factor and at that price point, I suspect the clones can't be doing what the top brands can't or don't for less money. Breakers are one place where I think it pays to stick to reputable brands that are trusted by the industry.
 
Dzl said:
Personally, I don't have experience with that breaker, but I would avoid it, it looks like one of the many off brands copying Bussmann breakers. If the reputable brands can't or don't make a breaker above 150-200A in that form factor and at that price point, I suspect the clones can't be doing what the top brands can't or don't for less money. Breakers are one place where I think it pays to stick to reputable brands that are trusted by the industry.
Click to expand...
So better a 'megafuse' then and simply carry a spare.
 
Solarfun4jim said:
So better a 'megafuse' then and simply carry a spare.
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A reluctant yes, would be my opinion, unless you want to shell out the money for a quality 250A+ breaker from a reputable company or could possibly get away with a 200A breaker which would be cheaper and more readily available.
 
I ended up using a Class "T" 200 amp fuse on my inverter feed from my battery bank to the inverter. The fuse holder and fuse will set you back at least $60, and a replacement fuse is $25 or so. But it sure is cheaper than fire damage.

My individual battery strings are on 125 amp MBRF fuses. They should handle it, but they are a bit close, with just a 58 volt rating. Full charge could hit 58.8 volts, but I have it set to stop at 57.6 volts. On a lower voltage system, MBRF fuses should be fine, but if your battery bank can supply more than 5,000 amps of short circuit current, they still might sustain an arc inside. On a 48 volt system, they are only rated to interrupt 2,000 amps. If my system suffers a dead short, they may arc over, and the Class T will be the safety valve.
 
smoothJoey said:
Why are you so keen on mega fuses?
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Thanks Joey, I'm not particularly keen on Megafuses, but open to your suggestions. The inverter output can peak at 6000W (for a few seconds) and with the 24V setup, im estimating that it could draw 250A. I would prefer something that could be 'reset' rather than replaced if blown. I really dont expect my loads to test the full inverter capacity, but there is always the one circumstance that blows the fuse when you are in your RV, miles from anywhere...lol.
Would it be worthwhile adding a cheap 300A megafuse inline, so that if the breaker didnt trip, the fuse would blow (as a belt and braces senario....cheaper than $120 for a 'quality breaker') ???
Im assuming of course that the circuit breaker would trip long before the fuse would blow? (fuse only for back up)
 
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Class T and MRBF are two that are often used for main battery protection and/or inverter circuits. These also tend to be the two types I've seen recommended by inverter manufacturers.

Edit: Personally I wouldn't bother with any shenanigans with the cheap breakers, I understand your desire here, but its the wrong place to pinch pennies I think. Particularly because even with the cheap/knockoff 250A breaker, you are still 50A shy of the inverter manufacturer recommendation of 300A.

If you properly size your main battery fuse, there is little chance of it ever blowing unless there is a big problem, in which case reset vs replace is the least of your worries.
 
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Dzl said:
Class T and MRBF are two that are often used for main battery protection and/or inverter circuits. These also tend to be the two types I've seen recommended by inverter manufacturers.
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Cheers DZL. I'm not sure these are as readily available in UK, but i will cost out online.
 
Solarfun4jim said:
Cheers DZL. I'm not sure these are as readily available in UK, but i will cost out online.
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I believe blue sea is internationally available and they supply MRBF not sure about class T (or equivalent). To be clear these are fuse types not brands.

Also, edited my previous comment to add more, if you didnt catch taht reread the last paragraph.
 
Dzl said:
I believe blue sea is internationally available and they supply MRBF not sure about class T (or equivalent). To be clear these are fuse types not brands.

Also, edited my previous comment to add more, if you didnt catch taht reread the last paragraph.
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Found a supplier of MRBF fuses in UK...so have ordered those. Cheers for your input DZL.
 
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Solarfun4jim said:
Would it be worthwhile adding a cheap 300A megafuse inline, so that if the breaker didnt trip, the fuse would blow (as a belt and braces senario....cheaper than $120 for a 'quality breaker') ???
Click to expand...
If you are considering that I would suggest a fuse and a disconnect switch.
I'm partial to marine rated battery fuses because they go right on the battery positive terminal which pretty much excludes the possibility of an upstream short.
Class t are expensive but have the best interrupt rating that I know of.
The other safety equipment that I've started recommending is a fire extinguisher.
I also suggest you get an IR thermometer to check each connection point while stress testing the unit.
 
Solarfun4jim said:
MRBF already ordered. Will simply run a 300mm length cable with the m6 connector at one end and a m10 connector at the other. Battery screw one end, m10 bolt&nut through the fuse holder.
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That's too long.
The fuse should be as close to the terminal as possible to minimize the chance of a short upstream.
 
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