What Size Fuse For 100w Solar Panel

Annotation: If yous are unsure well-nigh this area, consult an electrician. Proper utilize of fuses and breakers are of import to maintain prophylactic.

The offset thing to know is that fuses and circuit breakers are primarily used to protect the system wiring from getting too hot and catching fire. Secondly, they also are used to protect devices from catching fire or from becoming more seriously damaged if in that location is a short excursion.

A good case is a 12V pb acid battery. If a short develops in your AC/DC inverter for example, a fuse betwixt it and the bombardment will forbid a possible explosion of the battery and information technology will cut the circuit fast enough to prevent the wires from communicable burn or getting dangerously hot. In this case, the battery, wires, and Air-conditioning/DC inverter will be safely disabled by the fuse.

Solar Panel fusing

Commercially fabricated solar panels over 50 watts have x gauge wires capable of handling upwardly to 30 amps of current flow. If you connect these panels in serial, there volition exist no increase in electric current flow so fusing is non required for this string. This is not the case when you lot have panels connected in parallel, as when connected in parallel the organisation current is condiment. For example if y'all have four panels each capable of up to 15 amps, and then a brusk in one panel can draw all 60 amps towards that short-circuited panel. This will cause the wires leading to that panel to far exceed thirty amps causing that wire-pair to potentially catch fire. In the case of panels in parallel, a 30-amp fuse is required for each panel. If your panels are smaller than 50 watts, and utilize but 12 judge wires, and 20 amp fuses are required.

Parallel/Combiner Box fusing

In a parallel system a combiner box is used that holds the fuses/breakers to each console, plus ane or more "combined" fuse leading to the accuse controller or filigree tie inverter (see figure). When sizing this "combined" fuse/breaker, we must first determine the worst case current that will menstruum based on our specific panels.

If we take the example 144-watt 12V panel from the introduction section, and look at the short circuit current (Isc), nosotros see information technology is rated at 8.5 amps. This however tin can exist exceeded if the actual installed situation does non lucifer the "standard" test conditions used for solar panel factory ratings. The industry rule is to increase Isc by 25% to encompass this possibility, and then information technology now is x.625 amps in our case.

The National Electrical Code (NEC) too requires that a 25% factor exist added if the load is continuous, so the number grows again to 13.28 amps per console. If at that place are 4 panels in this parallel fix, so the combined electric current can theoretically be as high equally 53.125 amps.

The chart below shows the ampacity for wires in a conduit per the NEC. Annotation that some wires of the same gauge can handle more amps and higher temperatures. An viii AWG USE-two wire set (minimum) from the combiner box to the charge controller in our example volition suffice, since it can handle 55 amps. A sixty-amp fuse or billow should be used in this case to protect this wire prepare. This likewise aligns with the maximum capacity of the charge controller selected.

Charge controller to Battery Fuse/Breaker

With a Pulse Width Modulated (PWN) charge controller, the worst-case amps flowing to and from the controller are the same, and so the fuse and wire size tin can lucifer. MPPT charge controllers, on the other hand, are able to both lower the voltage and increment the current flowing betwixt the controller and the battery bank, so the exact size wire and fuse size must be recalculated or obtained from the charge controller manual. Every bit an example, Blue Sky recommends a 60-amp fuse/billow for their Solar Heave l (amp) charge controller between the unit and the bombardment bank. Over again, select a wire that is rated appropriately.

Battery Fuse/Breaker to Inverter

The wiring and fusing from the bombardment to an Air conditioning/DC inverter is of critical importance because this is where the near electric current will likely flow. Similar to the charge controller case, the recommended wire and fusing should be obtained from the inverter manual. It is very likely the capsize already has a congenital in fuse/breaker on the input as well as the output (Air conditioning) side of the unit. A typical 1500-watt 12V pure sign wave inverter draws upwardly to 125 amps continuously, a number that increases to 156 amps in one case nosotros factor in the NEC continuous-use 25% adder. For Use-2 wires, 1/0 AWG is required in this example. For a hobbyist, welding cable is mostly used with these full general limits:

#4 AWG 150 amps
#2 AWG 200 amps
#1 AWG 250 amps
i/0 AWG 300 amps
2/0 AWG 400 amps

Final Note:

This article was just an introduction. There are important related aspects such equally cable length and fuse/billow types that need to be studied before a design is finalized. There are diverse free fuse and wire size calculators online that you lot should apply in completing your solar PV organisation. If your accept your fourth dimension and apply the correct combination of rated parts, then the system should work well and you'll slumber ameliorate knowing you engineered it to be safe and reliable.