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Small Cabin Forum / Off-Grid Living / 200 watt solar system help needed
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# Posted: 14 Dec 2019 16:50 - Edited by: xtolekbananx

Hello. I'm thinking about getting 200 watt solar panel system. I have basic idea how to set it up but need some help. First I will only use this for light, phone charging and laptop charging. I have 3 x 6w led lights in main room and 2 x 6w in the other. One laptop that I use sporadically and of course a phone sometimes a few when I have company. I would also charge my phone battery pack during day when my battery is full.

I was thinking getting 2 monocrystalline renogy 100 watt panels from amazon.

Then I was thinking of getting a 30amp charge controller

I was gonna put either 1x100ah gel battery or 2x75ah batteries. Are those two 100 watt panels enough to charge 150ah in batteries?

Also the panels will be mounted on the ground about 4-5 off the ground next to the cabin as my cabin is in the shade in the morning and I want the panels to be in the sun all day. This would require me to run at least 30 feet of wire from panels to charge controller. Now the question is what gauge wire should I use?
Would this wire be ok?

If I'm missing anything else please point it out, this is the first time I'm doing this. Also I would have 1000w power inverter in the system.

I have a inverter generator do run my tools and vacuum and other power hungry stuff. I just want it for lights, phone and laptop and maybe a small TV in the future. Thank you for your input

By the way I'm in Otsego county NY.

# Posted: 14 Dec 2019 17:23

the short answer is yes it will work just fine. depending on how much sun you get will depend on how fast your batteries charge. But on a normal sunny day it doesn't sound like you will have any issues. You can always limit your usage if your getting lots of no sun days.

if your a weekender, you will have no issues having charged batteries when you return.

The 10awg wire you linked is just fine for that distance.

# Posted: 14 Dec 2019 18:54

I hope you have better luck with Renogy service than I did.

They had a packaged deal that was just about perfect for my needs- Panels, charger/ inverter, and lithium battery.
They messed my order up and after fighting with them for about 2 months, I had to get Amazon to force them to refund my money.

I was able to find and order comparable components off e-bay for roughly the same price or cheaper. Some of the companies didn't have a track record- neither good or bad- but so far all the parts are working good.

# Posted: 14 Dec 2019 20:35 - Edited by: JDH83VT

I have basically the same setup and near identical usage as what you describe. The Renogy stuff has served me well for a few years (but I didn't need to battle with customer service, that's always a headache!).

That wire size is adequate for the distance. One suggestion, go a little bigger on the battery bank. I have 200 ah bank and sometimes it isn't enough, especially in the winter. I would consider going to a minimum of 300 ah for the batteries. If you really think you are going to add a tv, you'll need the extra.

# Posted: 15 Dec 2019 10:59 - Edited by: jhp

I think you'll be fine in general but depending on the age of the laptop and the TV you might draw a lot more power than you think. I'd say get a kill-a-watt meter and check for sure.

A 5+ year old LCD TV will draw double the power than a newer generation LED TV will.

I had an older LCD 24" TV that drew about 34 watts running. I later upgraded to a year old 40" LED TV that drew 38. You'll find the same with your laptop and its charger.

The important thing to figure out is your total power draw per day, then size the system according to that.

Your 200 watt panels might be good for 80% of that rating or 160 watts per hour in full sun under optimal conditions. A 12 volt system at 160 watts per hour is charging 13.3 amps. If you get 3 hours of full direct sun (use optimal peak conditions only) per day thats just under 40ah of capacity you put back into the battery each day.

I had a 100 watt system tied to a 100ah battery and it worked okay for me, but my total max draw was about 60 watts and always for 10 or less hours a day, more often like 6 hours a day. It was always ready to go when I got there for the weekend and if it was cloudy that weekend the bank was needing charging at 50%-ish when I left.

I also had a cheap "suitcase" generator and a battery charger I would use for longer trips that was cheap weekend insurance for a couple hundred bucks.

Your performance in the summer will be much better than in the winter, something else to keep in mind.

I'd say buy the kit you have laid out with the 150ah battery bank. If you need to you can always throw another panel at it later, and you'll find out quick enough if you want to add another battery before you'd want to have replaced them all to keep them the same age.

Last suggestion - don't trust any of the power information coming off the charge controller - buy a couple of $15 power meters on Amazon - wire one to the battery bank showing the exact state of charge, and another either coming off the panels or going into the bank showing your actual charge rate.

Okay really the last thing now - do you really need a 1000 watt inverter? Keep in mind the inverter draws a bunch of power on its own just to run - more if it has load sensing electronics and cooling fans. Size your inverter roughly to your expected load. I found a 400 watt inverter that only draw like 5 watts running and even that wasn't very efficient. A 1000 watt inverter might be drawing 15 or 20 watts just idling.

# Posted: 15 Dec 2019 21:25

I have a small system also, with just 128 watts of panels and a 100 AH battery. Something I consider critical is a properly sized high efficiency inverter. The best inverter I have found for this is the Morningstar SureSine. It is a pure sine wave inverter that puts out 300 continuous watts with 600 peak watts for ~10 minutes. Its peak efficiency is 92% with a 55mA self consumption in standby mode. There's nothing else like it on the market that I have found. It will handle everything in your list.

# Posted: 15 Dec 2019 22:25

I have been happy with my small Renogy 100 watt package. I have had it for 6 years, or so and have 2 golf cart 6volts bridged getting power from it. I am in northern NY and just brought them home for the winter to my home.

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