How To Size Dc Breakers For Solar Panels

Sizing the dc segment between the solar panel and the charge controller.

How to size dc breakers for solar panels. Then divide the kw output by your panel s efficiency to get the estimated number of solar panels you ll need for your system. You use a breaker with a voltage rating for the type of current dc and amps to protect the wire gauge. To determine the appropriate size of circuit breaker for single phase supply it depends on multiple factors like type of load cable material and environment temperature etc. To calculate the fuse size required between the string and the inverter s dc input you take 9 12 x 1 56 14 7 and round up to the next trade size of 15a.

The first is the pv disconnect or array dc disconnect. Let s begin with sizing the conductor wire coming into the combiner box. A solar pv system typically has two safety disconnects. 1 1 sizing the fuses f1 f2 f3 connected in series of each solar panel.

Solar inverters convert the low voltage dc electricity created by your solar panels to the 120 volts ac electricity used by household appliances. How to choose the right solar inverter size for your solar power system. The second disconnect is the ac disconnect. The closest match would be an abb 10a 1000v dc circuit breaker or a combination of an 1000v rated 8a fuse with a 1000v dc isolator fault protection is not technically required for single strings.

Now these are often included with some inverters but it s a good idea to check. Dc cable sizing tool this online cable size calculator tool makes it easy to establish the correct size of cables for any dc power system. The general rule of thumb is that circuit breaker size should be 125 of the ampacity of cable and wire or the circuit which has to be protected by the cb. The wire must sustain at least the maximum circuit current.

In an array of 8 panels the solar generation system will have a series connected voc of 8 x 45 3v 362 4v and isc of 5 56a 1 25 x 5 56a 6 95a and 2 x 1 2 x 362 4 869 76v. Do you have access to a 60a dc breaker not an automotive or car stereo breaker. The ac disconnect is used to separate the inverter from the electrical grid. What size wire will the controller accept.

So manufactures do not supply these with their inverters. Here s a chart for wire sizes looking for 60a 4 is safe 6 is possibly allowable if you have the high temp insulation. The pv disconnect allows the dc current between the modules source to be interrupted before reaching the inverter.