Wire and fuse suggestions for your diy 12v solar power system

Suggested WIRE Sizes for Common 12v Inverters:

These suggestions are for PURE COPPER WIRE ONLY. The best copper wire is often called “Welding Wire” because it is rated for high amperage usage as well as high heat tolerances. I DO NOT recommend using copper clad aluminum wire for anything. It’s dangerous and you risk causing a fire. It can be tempting to use the minimum you can get away with because the price of copper wire is rather expensive, but my best advice is to think of wire as an investment for the long term in your solar system, this is not the place to skimp. With that in mind, I recommend getting even thicker wire than recommended if you plan on upgrading later because you can always use bigger wire that is over rated even on smaller inverters. So, say you plan to start with a 1000w inverter, but you have plans to upgrade to a 2000w inverter later, it would be a good cost saving measure in the long run to go ahead and buy 1/0 wire now and use that for your 1000w inverter, and when it’s time to upgrade to 2000w you don’t need to replace the 2 awg you already paid for, and then buy 1/0 later. Copper wire goes up year after year, and it lasts for ages, so get the biggest wire you can and save yourself money in the long run.

If you intend to use your inverter for a sustained period of time you definitely want to go with the “Recommended” size or larger rather than the Minimum wire size. The minimum size is ok if you only really plan to use your inverter at around 50% of it’s rated power most of the time, and an occasional max usage for less than 30 minutes or so at a time.

Note: These suggestions are for wire runs of LESS THAN 10 feet. If your wire lengths NEED to be longer than 10 feet, you should reconsider your options on the placement of your battery and inverter to bring them closer, otherwise you are going to need thicker wire… the longer the wire run the thicker the wire needs to be and for this I recommend doing more research before using these suggestions.

Inverter WattageMinimum Wire SizeRecommended Wire Size
500w8 awg10 awg
1000w4 awg2 awg
1500w2 awg2 awg
2000w2 awg1/0 awg
2500w1/0 awg1/0 awg
3000w2/0 awg2/0 awg

Suggested FUSE Sizes for Common 12v Inverters:

The important thing to understand about fuses is that their purpose is to protect your WIRE. Because of this, its important to know that, unlike wire size, bigger is NOT better. At the same time however, too small of a fuse and you will be blowing fuses all the time and you don’t want that either. A fuse is designed to melt before the wire if there is too many amps going through the wire and disconnecting the circuit to prevent a fire or damage to equipment. Remembering that the main purpose of the fuse is to protect your wire, if you use higher gauge wire than was recommended above, you CAN also use a higher amperage fuse, but that would make things more complicated and I would just stick to the recommended fuse size anyway. For a 12v system you can use either an ANL or AMG/MEGA type fuse. There are other options but I’m trying to keep this simple.


Inverter WattageSuggested Fuse Size
500w50-60 amp
1000w100-150 amp
1500w150-175 amp
2000w200-225 amp
2500w250-275 amp
3000w300-350 amp

Suggested WIRE Sizes for Common MPPT Solar Charge Controllers:

It’s very important to always connect your battery to the charge controller before you connect your solar panels because you risk damaging the charge controller. It’s best to look in your manual to determine the correct wire size for your inverter because some brands only support the minimum size wire at the terminal post, so all I can give you here is a rule of thumb, but it may not apply to all charge controllers because the terminal posts are often those slip in type where you either use bare wire or a ferrule end rather than a ring or fork style of terminal.

Controller Amp RatingSuggested Wire Size
10a 16-14 awg
20a12 awg
30a10-10 awg
40a10-8 awg
50a8 awg
60a8-6 awg
80a6 awg
100a6-4 awg

Suggested FUSE Sizes for Your Charge Controller:

Again, you will want to confirm that this gauge will fit into your terminals. I always go with the max size wire I can fit. Install an inline fuse or breaker rated for the same rating as the controller or the next size up… so, a 40a controller use a 40-50a fuse/breaker, a 60a controller use a 60-80a etc…

Charge Controller Amp RatingFuse Suggestion
10a10-15a fuse
20a20-25a fuse
30a30-40a fuse
40a40-50a fuse
50a50-60a fuse
60a60-70a fuse
80a80-100a fuse
100a100-120a fuse