Diy combiner with fuses (budget)

Hi there, I’m installing a simple 400w system in a converted van. It comprises of a Morningstar pro star ps30 pwm charge controller . 4 100w panels (parallel) 1x 115ah battery (possible future upgrade to 220ah)
The panels will be mounted flat to the roof hence the over panelling for the 115ah battery. I am installing this system to a tight budget for a friend, she already has the panels and the pro star controller. My question is regarding the combining of the panels. I plan to do this up on the roof into an ip67 box using glands and busbars. This will be diy made. The budget doesn’t stretch to buying breakers. Can I use fuses? The isc of the panels is 5.7a so times 1.56 = 8.89a can I use a 10a blade fuse for each panel? I have drawn a diagram of what I plan to do. Can anyone advise me if this is ok? Any advice would be much appreciated. Thank you, Jim
England
The panels will be mounted flat to the roof hence the over panelling for the 115ah battery. I am installing this system to a tight budget for a friend, she already has the panels and the pro star controller. My question is regarding the combining of the panels. I plan to do this up on the roof into an ip67 box using glands and busbars. This will be diy made. The budget doesn’t stretch to buying breakers. Can I use fuses? The isc of the panels is 5.7a so times 1.56 = 8.89a can I use a 10a blade fuse for each panel? I have drawn a diagram of what I plan to do. Can anyone advise me if this is ok? Any advice would be much appreciated. Thank you, Jim
England
0
Comments
Blade fuse HOLDERS are often pretty cheaply made, and you will be running amps through them, so good heavy duty holders are required.
I've seen 30A holders melted with 5A fuses in them, the contacts are so bad, they heat up, melting the holder.
When powered up, you cannot remove a fuse, or it's likely to arc badly, which is way too much fun for being on the roof.
Eventually, cheap fuses and fuse holders will fatigue from thermal excursions, premium ones will last longer.
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Thanks, Jim
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
Jim
2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.
You could use a fused power distribution block that would work with midget fuses, some thing like this;
Usually they are designed for high end car stereo's. Cost for this is $20 in US. The midget fuses come in AC and DC versions. be sure to get the correct amperage and type of fuse.
Looks like you could buy this 5 pack of din rail fuse holders;
https://www.ebay.co.uk/itm/5x-RT18-32X-AC-380V-32A-1-Pole-10x38mm-DIN-Rail-Mount-Fuse-Holder-Base-I1S-F7X2/282513180276?_trkparms=aid=555018&algo=PL.SIM&ao=2&asc=49569&meid=4efaa763477a471996a247dd39fa6614&pid=100005&rk=1&rkt=2&sd=172958786364&_trksid=p2047675.c100005.m1851
and then find the correct fuse, These are fast acting 10 amp fuses KLK;
https://www.ebay.co.uk/itm/BARGAIN-10-X-KLK-10amp-Midget-Fuses-quick-blow-ceramic-600VAC-10x38mm/222755564748?epid=2055821616&hash=item33dd442ccc:g:m7QAAOSw5cNYFmMW
and a small section of Din rail;
https://www.ebay.co.uk/itm/10CM-Din-rail-35mm/222281260424?hash=item33c0fedd88:g:3ckAAOSwzaJYAJH7
Photowhit: thanks for the ideas! I’m looking for suitable sized enclosures and fused power distribution blocks.
Jim
Another way to do it would be to use 2-way paralleling mc4 connectors (no fuses needed for 2 in parallel), and run the two + wires to a pair of breakers next to the controller. Total cost may be close, and you don't have to mess with mounting box and fuses on the roof.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
So a pair of Y branch connectors for each pair of panels wired in parallel. Two sets of cables coming down into the truck ++ - - the two ++ going into their own separate fuses and then combined together after the fuses and into the charge controller. Sounds much easier up on the roof and nicer to disconnect down in the truck. Thanks Estragon!
You will also want a fuse or breaker from controller (and inverter, if using one) to the battery. Note that pv should be depowered before battery, and repowered after battery, which is easier with breakers. Controllers should be booted up with stable battery voltage, as unstable pv voltage can cause some controllers to boot wrong.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter