Will this solar set up work ok?

[candyman]

So i recently was gifted a felxible HQ 100 watt panel, renogy 30 amp wanderer pwm controller. I plan to use 50' of cable so I can park in shade and put the panel in the sun. This is going to an aux second battery marine deep cycle. My use is low, cell phone charge, some lights at night, propex and maybe a radio. I Have heard that the wattage is fine based on my use but due to the length of my panel wire (10 or 12 gauge) the pmw controller may not do a good job and that an mppt would be better. What do you all think?

[newfisher]

I run a 100w panel and run a MPPT controller with good results.

[dgbeatty]

Fifty feet is a long way for a 12volt circuit. Using 12ga wire should be considered the minimum with 10ga preferred I would think. But on the other hand a 100watt panel is doing very very good to produce much more than 5 amps on a sunny day. Just my experience.

Dan

[spacecadet]

http://www.calculator.net/voltage-drop-calculator.html

10ga. Electricity is like water.
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[DubNuts]

[candyman]

Thanks all, i guess to clarify my question, will this pmw be up to the task or should I consider an mppt?

[ThankYouJerry]

[candyman]

[jmranger]

Solar threads tend to gather tons of opinions, which don't always point in the same direction - probably because everyone's need are different. Here's my take.

For small system like yours, the difference between PWM and MPPT is pretty much zero.

My recommendation would be to buy as little as possible for now, as you build experience with what you already have in hands. But for anything you buy, it might be better to go one (and only one) size up, so if you're wrong, you might get away with using what you bought anyway.

Be sure to have a tool to monitor your battery state as you build experience with the system. A simple voltmeter is fine. The LED indicators on some controllers (that tell you when the battery is fully charged) is another - if your battery is full at 10AM, you know you don't need to worry.

Regarding wire size, I personally feel that many get carried away, and way oversize their setups. If you're afraid of the voltage drop, consider purchasing multiple shorter cables (3x20ft?) with quick connects, and only use those actually needed in a given setup.

You haven't stated if you plan to connect your aux battery to the alternator or not. It may or may not make a difference - mostly depending on how much you use your propex & radio (I'm assuming that your lighting is LED). Those can be a significant load on the battery, and will influence whether your solar panel needs help of not.

Have fun,

JMR

[jmranger]

Missed a few posts while I was writing. So to complete:

Simple answer to your question is yes, it will work. Yes, compared to an MPPT, you'll lose some power in perfect conditions (since the panel will output 20ish volts and the battery will use only 15ish) and you'll loose some charging hours (when the sun is low, the solar panel's voltage will be too low to be useful - an MPPT would fix this - but with a low sun, the panel output is low too, so the loss is marginal).

But the 20% figure is right too. Switching from your 100W solar panel to a 120W panel would give you roughly the same gain as switching from a PWM charger to an MPPT charger.

Calculations on voltage drop on the wire are based on the full output power of the panel. When the battery gets closer to full (or the wire gets longer or thinner), the panel doesn't stop working - it just charges slower.

Back to what I wrote initially: try what you have, gain experience, then fix whatever's broken for your particular needs.

[ThankYouJerry]

[candyman]

Thanks guys this is great advice and direction. I will use what I have and see how it does! I want to keep it is as simple as possible and with my low draw needs, hopefully this system will be just fine! My second battery is comnected to the alternator so that will help for sure
Best

Edit; i like the idea of doing multiple 20' runs of tha cable to see about voltage drop. I have a bunch of the mc4 connectors so that would be an easy fix, thanks for that advice

[crazyvwvanman]

For 60 feet of wire I would just make a 20 foot set and a 40 foot set.
That lets you have 20, 40, and 60 with only 2 sets.

Mark

[candyman]