Cable Size for Solar Panels - How to Size Wire for Voltage Drop

🎁 Free diagrams: cleversolarpower.com/free-dia...
📖 My best-selling book on Amazon: cleversolarpower.com/off-grid...
Link to the voltage drop calculator: www.rapidtables.com/calc/wire...
I'm here to shed light on a crucial aspect often pondered by solar enthusiasts: "What size solar cable do I need?" In this detailed video, I explore the intricacies of solar panel wiring, ensuring your setup is as efficient and safe as possible. Whether you're navigating the calculations for a single solar panel or delving into the complexities of a hybrid solar panel system, this guide has you covered.
Understanding how to calculate cable size for solar systems is vital for minimizing energy loss and enhancing the safety of your solar setup. We begin with a clear explanation of solar panel wiring basics, detailing how electricity flows from your solar panels to the charge controller and the role of a combiner box in parallel configurations. This foundational knowledge is essential, especially when determining how to size wire for solar panels correctly.
In the journey to optimizing your solar system, we dissect the differences between series and parallel wiring. I recommend wiring in series to leverage the maximum allowable input voltage of your charge controller, reserving parallel connections for specific scenarios like shading issues or when using a PWM charge controller. This strategy is key to ensuring your system operates at peak performance.
A practical example illustrates the simple process of wire sizing, considering both the current and the length of the wire. For instance, calculating the maximum current for a 100W solar panel and assessing the necessary wire size using an online voltage drop calculator showcase the process in action.
Further enhancing the guide, I delve into a more complex 2 series, 2 parallel (2S2P) wiring diagram, demonstrating the calculations and considerations for a system that incorporates a combiner box. This segment not only highlights the technicalities but also offers valuable tips, such as the cost-effectiveness of correctly sizing solar cables and strategically positioning the charge controller to minimize wiring expenses.
00:00 Introduction
00:40 Solar Panel Basics
01:34 Sizing a wire
04:07 Hybrid system calculation
05:49 Reduce wire cost

[@cleversolarpower]

My book on Amazon: cleversolarpower.com/off-grid-solar-power-simplified 7 Free off-grid solar diagrams: cleversolarpower.com/free-diagrams/

[@DONKEYdaDON]

I've tried for months to get a straightforward explanation with voltage drop and series/parallel...you sir are a gentleman and a scholar!

[@cleversolarpower]

Thanks for your kind comment.

[@brushbum7508]

THANK YOU ! TAKE CARE..

[@Electronzap]

Good info.

[@FayazAhmad-yl6sp]

Very informative vedio.

[@darrylm3627]

😄👍Good Stuff, Great Tips

[@vaelectrical]

Thank you for this video sir I just followed

[@cleversolarpower]

Welcome aboard!

[@MaddulaSrinivasan]

Excelent

[@Ekanselter]

Very well explained. Voltage Drop is often overlooked in all aspects of electrical design resulting in power being lost to heating (and possibly damaging) the wire.

[@salsepulveda494]

I don't recommend connecting solar panels in series at all. You need AMPS to charge batteries, and you need a charge controller that will handle the AMPS being sent to it. I have four LiFePO4 batteries in parallel (400AH). I have Qty 4 Solar Panels (100 watts each). 100 Watt Panel = 5.25 Amps +, Qty 4 Panels = 21 Amps, sometimes a little more, possibly 22 or 23 Amps on a good day. Charging the batteries at 22 Amps or more is pretty good. We need Amps, not Volts. A 100 Watt Solar Panel only needs a 16 to 14 AWG Wire to carry 5.25 Amps plus, however, once you bring it all together, you'll need a 12 to 10 AWG Cable to carry 22+ AMPS to the Victron 100/30 Smart Controller. I use 32ft. of 10 AWG Wire (rated to 30 Amps) to be safe. I power a small college refrigerator and two freezers using a 3000/6000 Watt Inverter, pure sinewave output signal. From the battery, I'm also using a Victron 500 Smart Shunt. It's all monitored on my cell phone, through Bluetooth. I works great.

[@cleversolarpower]

This is not true. The mppt will convert the voltage into current because power=volts x current. Power in equals power out - efficiency loss. I recommend watching my video about pwm vs mppt where I discuss how current transformation works.

[@salsepulveda494]

@@cleversolarpower OK - you're correct. I forgot about that. Thanks.

[@edkemp6287]

Lol noob. Use high voltage string and save money on copper. Wire battery in series.

[@vaelectrical]

​@@cleversolarpoweryou are right sir From experience, series wiring is preferable

[@saniabdullahi393]

As copper is not cheap at all​@@edkemp6287

[@JalaramEnergy]

CAN I CONNECT 48V SOLAR PANNEL TO 12V/24V CHARGE CONTROLLER ? I HAVE 12V SET UP BATTERY 12V, INVERTER 12V, 50ACHARGE CONTROLLER 12/24V AND 3 SOLAR PANNEL 150W/12V EACH

[@wuqinxue7065]

I know W=VA now. Thank you. Can we use solar panel of different brand names in the same system please? Or do we have to use same brand names of controllers, panels, inverters and batteries, please?

[@cleversolarpower]

VA*0.8=W for example, the victron phoenix inverter with 1600VA has a power rating of 1600*0.8=1280W. You can use different brands. But for solar panels i would use the same brand and model, because they all differ a little bit ,which will lead to losses. Check my video about 'mismatched solar panels'.

[@NawtieBoy96]

6:39 here to reduce wiring cost we also buy another solar panel which is way expensive than the now (76$) to then (90$) wire cost :D so i dont see increasing solar panel voltage leading to wire cost savings 😅

[@cleversolarpower]

I knew this comment was going to come one day 😄. It's to prove a point, to always increase the voltage up to the max input voltage

[@Second-gear]

How long to wait for the free diagrams?

[@cleversolarpower]

There was an error with the deliverability. Can you try again?

[@IanMukewa]

What about stranded vs solid wires... Do they affect the efficiency/energy-loss?

[@matthewwakeham2206]

Victron require the use of fine stranded flexible wire with their solar charge controllers as solid wire doesn't give a good connection in the terminals which leads to heat and fire.

[@ghz24]

What is the logic behind the 1.56 safety factor add to the current? How will the panels make half again as much current? Isc is shorted out so that is the maximum current it can put out. I see 1.56 applied to the input current of a charge controller if it isn't continuous use. How does this apply to current in a wire

[@cleversolarpower]

It accounts for higher temperatures in the wire in an outdoor setting. Higher temps means reduced current carrying capacity of a conductor.

[@daliahammad8709]

​@@cleversolarpower In I-V curve , higher temp cause a slight increase in current, so why u are saying that the current will be reduced with higher temp?

[@manabouthome]

It's a safety factor required by the National Electrical Code.

[@manabouthome]

@@daliahammad8709 He didn't say the current will be reduced. He said the current carrying capacity of the wire is reduced. As it gets hotter, as you say, current increases, but wire current capacity decreases. That's dangerous.

[@johnpugh5747]

Can't seem to find these diagram

[@cleversolarpower]

Check the first link in the description.

[@melak2443]

What does it mean maximum system voltage 1000 volt dc on solar panels

[@stevehardyuk]

When you string solar panels together in a series, the voltage adds up. 1000 ÷ 20 = 50. 50 is the maximum number of solar panels ok.

[@panospapadimitriou3498]

@@stevehardyuk thats a factory not a house ... unless they are 100 watts each one.. the smaller the less efficient

[@stevehardyuk]

​@@panospapadimitriou3498100 watts yes

[@NeblogaiLT]

Solar panels have a limit, of how much voltage they can handle (once connected in series . It may be around 1000V for many models. Additionally, solar inverters have voltage limit too, it can be something like: 160V starting voltage, 600V optimum working voltage, 1000V maximum working voltage, 1250V open circuit voltage. In this case- inverter will turn on once it receives 160V, and be most efficient if it works at around 600V. To get that, you divide 600V by panel working voltage, say 43V, and get 600V/43V=~14 panels in series is optimal, and 1000V/43V is 25 panels in series is max the inverter and panels can handle.

[@cleversolarpower]

(600V*0.8)/43V=11 panels in series.

[@TommyJones49]

Just came to mind I have 10 gauge, but at the connections, the wires are very, very small/thin gage , so does that reduce the 10 gauge down to these small wires? Causing big energy lost? Thats how the wires came from manufacturer.

[@cleversolarpower]

Do you mean the terminals are too small to fit your wires? Then I assume your panels are in parallel. Check the maximum input current of the charge controller as well. You can add another charge controller to spread the current out.

[@TommyJones49]

@cleversolarpower Bluetti at barrel connector, maybe it's just not covered with the thick black sheathing a thin red an thin black wire come out. So think it's just not covered at the ends. My bad just wat they do it. Probably, sure same diameter inside bigger diameter just thicker covering.

[@manabouthome]

There's a need to be careful when designing series PV Module circuits. The voltage increases in cold temperatures, and that needs to be accounted for, so we don't exceed the maximum voltage of the MPPTs, conductors, and terminations. I recently saw a video where the guy used WAGO connectors on his PV wiring. They're only rated for 300 Volts. But series PV strings go up to 600 Volts.

[@cleversolarpower]

Indeed, this relates to the max input voltage of the MPPT. I made another video about sizing a charge controller, where I discuss this in detail.

[@junkerzn7312]

As a quick side note, you can look up "AWG table for power transmission" as a quick reference without having to worry too much about temperature or distance. The maximum amps for "power transmission" purposes in the official AWG table is a very conservative number that will result in minimal voltage drop at full load. So, for example, by this table 10 AWG is 15A. For people used to dealing with amps and cables, that might seem like a low number, but that's the actual specification "for power transmission". (For copper wire). Most Solar panel cabling is 10 AWG or 12 AWG. Certainly on larger panels. Little panels have thinner wires but also produce fewer amps. It isn't usually a problem unless you are paralleling a lot of strings. Using a combiner box with proper per-string fusing becomes very important in that regard. Plus you can also easily use a lower-gauge solar cabling for your higher-amperage back-haul from the combiner box to the charge controller / inverter. -Matt

[@salsepulveda494]

The table you're using is incorrect. In fact, 8 Awg is 40 Amps, 10 Awg carries up to 30-35 Amps, 12 Awg is 20-25 Amps, 14 Awg is 15 Amps, and 16 Awg is 13 Amps. Of course, 10 Awg will also carry 15 Amps. Just Google Amps vs. Awg size.

[@junkerzn7312]

@@salsepulveda494 There's a big difference between what a cable can carry and what a cable should carry. For continuous power transmission you want low losses and low temperatures, and you learn very quickly not to under-size cables. Otherwise your efficiencies go straight down the tubes. These aren't toaster ovens that see minuscule duty cycles. These types of systems run their max power for hours each day without a break. I'm using the correct table. -Matt

[@robtheplod]

Just use the max size cable the controller can take... that way if you add solar in the future you should be OK...

[@cleversolarpower]

If you have an unlimited budget, yes.

[@therevoman]

Isn’t it Voltage “rise” in solar?

[@cleversolarpower]

Over longer distances the voltage will drop. I made a dedicated video about voltage drop. Go check it out on my channel page.