Series would be fine for 10 AWG wiring with 600 volt PV wiring (I think this is UL 4703). This would let you stay with MC4 connectors.
After the SCC, the wiring would need to be thicker. I’d recommend installing the max wire from the SCC to the batteries (I think its 2 AWG, but it is in the spec book.). This would mean no need to do rewiring if you put more panels in parallel later.
My in my head math says 5s2p or 5s9p max. I also don’t know the power of the system you expect to produce. Min grew from a plan of 600 watts of panels, to actually installing 1000 watts, which over four phase got upgraded to 2550 watts of panels.
So, when you connect these panels, the ‘speed bump’ is usually the mc4 connector, which is limited to 10 awg and 30 amps, i recently found the mc4 3 to 1 and larger combiners are rated higher, but still the mc4 that connects to the combined side would just be 30 amp limit. So using the mc4 combiners, no more than 2 strings Combined or else the 30 amp limit could be exceeded. Without doing the cold weather math, my guess with a 250/100 is 5s2p.
You could of course use a combiner box and fuses and breakers and not have this limit. Maybe would be 5s9p to reach the voltage and amperage limits. Victron usually lets you slightly overpanel on their SCCs. I got my combiner boxes from Midnite solar. I can combine up to six strings.
Also, Amphenol makes an H4 connector that can take 8 awg that can plug into an mc4 connector. Each are UL rated, but probably not plugged in together. Even though you can find some for sale, the company discontinned putting tech specs on their website about the 8 awg version and only goes up to 10 awg. Not supposed to be a normal crimper for the 8 AWG, and that is expensive.
There are pre-made MC4 8 AWG connectors I can find for sale, but when I look closely at the specs, never mentions its an MC4 connector. Since it plugs in, might no make A difference. To me, to get a pre-madd, MC4 connector at 8 awg and have to splice a wire in, defeats the purpose of getting 8 AWG in the first place.
Our mission here at Shop Solarkits is simple: to make solar energy easy. That means easy to understand, user-friendly, and affordable. Today we address a common question. What size cable to use for a 12v solar panel.
What Size Cable to Use for a12v Solar Panel
Differences in Size
Different solar systems need different wire sizes. Even different parts of a solar system may need different sizes.
Solar power usually needs a 12 gauge AWG wire. But as the size may differ depending on resistance and flow, you need to determine the amps to know which size you need.
Standardized Sizes
Solar wires sizes are standardized using the American Wire Gauge (AWG). Wires with higher numbers generally have more resistance and can deal with lower currents only.
Metals
For most installations, aluminum or copper solar wires are used.
Copper wire has far better conductivity and carries more current than an aluminum wire of the same size. It offers flexibility and better heat resistance.
Understanding Cable Terminology
The voltage represents the potential electric potential energy of your solar panel per unit charge. Your solar panel’s peak power voltage is measured in volts and watts and is expressed as voltage maximum power or VMP.
A reduction in voltage causes a loss of power (V=IR) and an undersized wire can cause this reduction. This is represented with a voltage drop index.
Electrical current flows between the electrical circuits and is measured in amps. The rated current is the maximum that can be drawn in continuous use, without reducing the longevity of the solar panel.
Formula for Cable Size
When you invest in a DIY solar kit you’ll find that it includes almost everything you need. But with most technology, there’s a formula to determine what size cable you need.
Even if you are not outstanding at maths, you’ll find the calculation fairly simple. The formula is Amps = Watt / Volt.
Whether you’re installing solar panels on a boat or the roof of your home, the formula remains the same. If you know the watts and voltage of your system, you can find the amperage.
The amps will determine the minimum AWG cable size to use, based on a 2% voltage drop. In this case, you know that the voltage is 12V. Divide the wattage of your solar panel by the voltage to determine the amps.
Most often, you will need a cable gauge between 10 and 14. But a 14 gauge solar wire can only handle a maximum of 15 amps. And many solar panels need a higher amp.
When you are unsure of the amps, a 12 AWG cable may be the best bet. This is because a 12 AWG cable has an amp capacity of 20 with a 2% voltage drop.
Once you’ve determined the amps, you can choose the best gauge. But there is more to choosing the right cable than the diameter. Length also plays its part.
This is because the longer the cable, the higher the voltage drop. You need to factor this into your calculation. Longer cables may not always be feasible in smaller spaces, for example when installing solar panels on a van.
Why Cable Size Is Important
Every wire gauge (AWG) has a maximum current limit that the cable can handle before damage occurs. It is crucial to pick the correct size so that the cable does not overheat.
Risk of Overheating
Solar panels harness the sun’s energy and transform it into electrical current. Just like batteries, a solar panel has positive and negative terminals. And current flows from the negative terminal to the positive terminal.
Wires then transport this current to your electrical units. If too high a current is run through them, there’s a risk of overheating from too much energy. In certain jurisdictions, undersized wires and cables constitute a violation of the National Electric Code.
What Size Cable for 12V Solar Panel FAQ
Although mixing different wattage solar panels is possible, it reduces the efficiency of your solar energy system.
While you can use two charge controllers for one solar panel system, each controller must have its own solar panel block.
Solar energy is renewable, safe, and simple when used correctly.
But choosing the right wire size is essential for the safety and functionality of your solar panel. By following the guidelines and formula above, you’ll select the right cable size with confidence.
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