Solar Power System Circuit Breaker and fuse Amps

Question

So the question is kinda part 2 of my question about the DC Output

Today I went to Hellweg (It's like an Electronics shop in Germany/Europe). To buy a Circuit Breaker or Fuse (idk what I am looking for) for my solar system because I saw this pictures below:

and

Now My question is: What Fuse/Circuit size breaker do I buy? Because I went to Hellweg and there are like 1000 of them with different Apmps, Voltage, etc.

Example below of Hellweg stuff:

I have a 100 Watts Solar Panel, 50A Controller, Battery, etc. I read using a wrong circuit breaker and fuse will cause a fire.

What size do I buy to make the my Solar Power System like the diagram?

Updated with Specs:

1) Inverter: Aukey 1000 W 2) Solar Controller: Here 3) Battery: Solar battery 100 Ah C100 4) Solar Panels: One 100W PET Panel

Answer 1

You'll need to read the specs of those breakers to see if any of them can play with DC. For instance of many lines of breaker used in North America , precious few do (e.g. QO, but those only fit QO panelboards, they are not standard DIN rail like Euro panels). Speaking of DIN rail, there are loads of designed-for-DC breakers, just at EE/design type electronics shops like Mouser, not home improvement stores (except for the odd nuts like QO).

Also given the loads you want to run, you should really seek ways to run these direct on 12V DC. Inverting 12V DC to mains merely to power a wall-wart that makes 12V DC isn't even stupid. For instance if your TV can't take 12v direct, loads of other TVs can... get one of those.

Answer 2

Some answers in here:

1. None of those Circuit Breakers are useful for this application, because they are from AC loads, not for DC loads. You should use DC fuses which are common, or DC Breakers which are less common.

2. You have 12 AWG and 4 AWG, which have Allowable Ampacities close to 20A and 70A respectively, which would be a good starting idea for the fuses limits, for protecting the cables (only).

3. The Panel Fuses at the user end should be calculated according the circuits loads you are planning to install. Just like any Panel. If you want three circuits each with 5A each, you should then put three Fuses for 5A. And you should consider most of the design criteria you apply for designing AC Panels in here (which ones?).

4. The Inverter converts the DC into AC, which is not what you are showing in the diagram. I am actually not clear if you plan to supply DC or AC loads. I see you don't have that issue clarified either.

5. As for any Panel, for those current levels, you will require specific component for interconnecting the equipment and protections. Also I see you have not questioning about this. Remember the specs for AC should not be necessarily the same for DC. For 1W AC there are specific requirements.

As a final comment: Those current levels, without any experience, are like a suicide. This requires minimum electrical knowledge in order to not killing yourself or anybody close to your system. Your system omits all protection design. It is like an open energized wire ready to be touched.

Answer 3

Pay attention closely to breaker specifications

As it turns out, you don't need a fuse in the solar panel wiring provided you use adequately sized wire from the solar panel to the charge controller. This is because solar panels are inherently current limited sources; in your case, your panel specifies an Isc of just under 6A, so it won't put more than that out, no matter what happens, meaning that 1.5mm2 wire is plenty adequate for the panel connections.

However, the battery wires are a different story. A fully-charged lead acid battery can put out somewhere between 1000 and 5000A of short-circuit current, and you will need breakers or fuses that can handle such a fault at 12VDC. This means that you will need to check the specifications for the breakers you want to use; not only will you need a 50A and a 100A breaker, these breakers will need to have a minimum of a 5kA interrupting rating at >16VDC. Some IEC-style breakers are DC rated, but not all, so you must check the specifications for the breakers you want to use.

As to wire sizing, you'll need some fairly thick wires for the charge controller and the inverter. 10mm2 is a reasonable size for the wiring from the charge controller to the battery; however, you'll want to increase that all the way to 35mm2 for the wiring from the battery to the inverter as the inverter can pull much more current than the charge controller provides. You also may need to use fine stranded wire for the connections to the battery to avoid putting mechanical strain on the battery posts, which requires its own precautions for making good connections (such as using compression lugs instead of mechanical setscrews). You'll also want to connect the negative post of your battery to an earth ground stake, or use two-pole breakers if you want to leave it floating.

Don't get gassed!

A vented-type lead-acid battery, like yours likely is, releases highly flammable hydrogen gas during the charging process. This means that you will need to make sure that the battery lives in a quite well-vented space so that hydrogen can't accumulate and ignite.