12x12 Cabin - New to Solar - Please help!

[Doug24]

Ok, thanks again for that explanation.

For consumption

2 box fans - 100w each x 10 hours a day = 2000 watt hours
4 lights - 15w each x 5 hours a day = 300 watt hours

Looks like this could get fairly pricey, fairly fast!

Thanks!
Doug

[Sunking]

Ok, thanks again for that explanation.

For consumption

2 box fans - 100w each x 10 hours a day = 2000 watt hours
4 lights - 15w each x 5 hours a day = 300 watt hours

Looks like this could get fairly pricey, fairly fast!

You tell me

Panel wattage = 700 watts = $500 to $700
Battery AH = 140 AH at 48 volts. 8 x 6-Volt 140 AH batteries, or 4 x 6-volt 280 AH = $800 to $1000
MPPT Charge Controller @ 30 Amps for 24 volt = $300, not sure they make a 15 amp for 48 volts but would cost around $200 if such an animal exist

Just shy of $2000 for panels, batteries, and controller plus all the other stuff required. Is that expensive?

[Doug24]

Thanks for breaking it down, that's exactly what I was looking for. What panels you go with?

[Sunking]

Thanks for breaking it down, that's exactly what I was looking for. What panels you go with?

That is a trick question that you have to answer. Depends on how big you go. If over 200 watts, then use Grid Tied panels and MPPT controller.

I hate to keep repeating myself, but you got to get a handle on Watt Hours. The whole design is based on on how much power you use. But I will throw you this bone as a rule of thumb.

Work with 200 watt panels. Avoid panel numbers of 3,5,7 or any prime number except 1 and sometimes 3 like a 600 watt system.

So here are some choices.

400 watts of panels, 30 Amp MPPT Controller, 12 volt 250 AH battery system.
600 watts of panels, 30 Amp MPPT Controller, 24 volt 250 AH battery system
800 watts of panels, 30 Amp MPPT Controller 48 volt 250 AH battery.

The only difference is the number of panels and batteries. All the panels would be the same 200 watts, and all the 6-volt 250 AH battery is the same battery just more or less of them.

I can only take you so far without knowing where you are going.

[Ho jo]

Doug fwiw for 18 months in my rv I use 2 12 volt 14" fantastic breeze fans. $75 each 900 cfm on high 32 watts each for about 10 hours This fan on high gives more air than a 120 volt fan on med. But they are loud. And I have 5 leds at 2 watts each for 5 hrs $20 from flea bay. with a 30 amp epever mppt cc $125 and 3 100 watt panels. (I needed 4 panels for a pwm cc) $1 a watt and free shipping. And 2 6 volt 208 amp hr golf cart batteries $85 each.

[PNPmacnab]

For years I just plugged my house into the car. Get grid tie panels. I got 280W panels in your area for about $180 out the door. You won't do that with 100W 12V modules. If you don't buy two, you are a muggle. Everyone buys too few panels to be successful. The ideas here are way over thinking this.

[Doug24]

Thank you, HJ, that's a great suggestion and I will certainly look into it further!

[Doug24]

Thanks PNP, appreciate your insight as well. I should have mentioned that my cabin has a gambrel roof. The one section, the top angled piece best for the sun, would allow for about 12' wide of panels but only about 52-54" in height. As such, I need to have panels that will fit into that footprint. I suppose I could go over, to a degree, but it would look pretty bad. Any suggestions for that size? Perhaps two of these: http://sepbatteries.com/trina-240w-poly

[littleharbor]

Look into 48 cell modules. I see Yingli Panda series have them, 52 3/8" tall. May be hard to find in the U S though.

[Doug24]

OK, based on everyone's input, here is what I have come up with; the big items anyway.

Panels x 2 - SunSpark 300 Watt Mono SST-300W (these will fit the profile of my gambrel roof) - $474.96
Charge Controller - EP Tracer 4215BN 40A MPPT Solar Charge Controller - $188.50
Batteries x 4- Trojan 6v T-105 225AH (wired into 24v configuration) - $639.96
SolarEpic MT-50 Remote Meter - $28.00
SolarEpic Battery Temperature Sensor and Monitoring adapter RS485 to USB fit for Tracer MPPT - $11.80
SAMLEX PST-600-24 600W, 24V PURE SINE WAVE INVERTER - $243.00

$1586.22

Obviously fuses, hardware, shutoffs, etc. to add to this.

Thoughts?

[Matrix]

$160 each for the T-105s (well unless you are talking about the REs)? That seems a little hi. Forgive me if you already said, are you in the US? I would shop around for local sources. I have had them quoted at local distributors for a cash price of about $120.

And why not panel up to the max or near max of the controller. If you have to get panels shipped, I dont think you pay more for shipping of 2 than you would 4 or 6

[Doug24]

Thanks Matrix, the price I put on there was just the nearest retailer who sold them and yes, in central Illinois. I can certainly look around more and I appreciate you letting me know what they typically go for.

As far as the number of panels, I only have enough roof real estate on the best gambrel angle for more than 2. I don't really want to put them lower as my cabin area is roamed by my parents clumsy cows who seem to get into everything and knock stuff over frequently.

[Ho jo]

IMHO $1600.00 for a couple fans and 5 led lights is over kill. On a small system like yours. $600 on 12 volt is what I have in mine. I can get through 1 day of rain. And If I have full sun the next day my batteries get to float while running loads.

[Doug24]

HoJo -

So based on your comments, how about this:

1 - SunSpark 300 Watt Mono SST-300W - $237 (ability to add a second later or maybe start with 2, not sure) This is big as I can go for my roof profile and I feel would meet my limited needs.
2 - Trojan T-105 225AH battery wired to 12v - $300 est
1 - 40 AMP MPPT CC - $139

Run loads off 12 volts to get started (perhaps inverter down the road) but it gives me the flexibility to upgrade to 24v and more batteries. That's around $670 for the basics (one panel only).

That work?

[Ho jo]

Doug, first thing i would buy is a kilowatt meter and a dc clamp meter. Like sunking said you have to get a handle on your daily loads. If you are planning on using an inverter by all means go with 24 volts because they waste 15% or more of your power.
I only use dc fans and lights 12 volts is for small loads and it doesn't leave much room to grow. If your only gonna have 600 watts of solar panels on 12 volts you'll need at least a 45 amp charge controller.