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rugercpl
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# Posted: 26 Jul 2012 05:38pm
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I'm a new small cabin owner, and new to this forum. My cabin is wired for electric (panel box, wall outlets) but it's off grid and the previous owner has left me a new 5500 watt Briggs and Stratton generator that he used for electricity during brief stays during hunting season. Over the next year or two I would like to merge to solar power (at least partially), for recreational use of the cabin.
From the small cabin website, i like the turn-key solar power system outline of the motomaster (now Xantrex?) powerbox, inverter, and solar panel. It seems like any easy route to go, and with two or more could probably effectively power up my cabin for light recreational use. I'm sure there are plenty of DIY types here though who have built their own systems for the same or less money and with more power. I'd like to hear from you and compare shopping lists for a plug-and-play system. I do not have electrical knowledge beyond knowing not to stick my finger in a socket, and plan on getting the book "for dummies" about solar powering homes.
I guess your questions to me will be "what do you consider recreational use", and "what do you intend to need electric for (appliances etc)" and "how much sunlight do you have to work with".
Well....I will be staying at the cabin once a week for a night and a day..mostly working on landscaping by day (no electrical tools). The solar system will be mostly used for lights, a small TV/VCR, a crockpot, possibly a fan, a radio, and an occasional pump for either an outdoor propane shower, and pulling water from a stream nearby for non-drinking water. I might bring-in a small efficient refridgerator for overnight use, however I can always utilize a cooler with ice. The cabin gets direct sunlight for about four hours per day since the land is wooded
Can anyone share the pros and cons to the powerbox outline? Have there been advancements in the technology and I should put together my own system? I think the recipe was a 1200 Watt powerbox, 15 Watt solar panel, and 7 amp inverter.
Thanks in advance!
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VTweekender
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# Posted: 26 Jul 2012 06:11pm - Edited by: VTweekender
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Welcome to the forum!! Glad to have you aboard!!
What you are describing as the powerbox, with those light components that is a trickle charger, not nearly enough to do what you want.
The complete system is pretty easy to hook up. Solar panel wires to the charge controller, from the controller to a deep cycle battery, from the battery to an AC inverter.
If you use mini a fridge and light use with the crock (2 hours max maybe) you could get away with a lighter system, fridge is a heavy draw for a small system, the crock pot is a big draw as well, heating element in there.....but for just 1 day you would have enough with the system below..as it would fully charge while you are away.....if you try and go 2 full days running your appliances it might draw down to far..
100 to 140 watt 12v panel (18v panel will work too)
20 amp charge controller
120 Amp Hour deep cycle battery
1500 watt modified sine wave DC to AC inverter
MC4 wires to length needed from panel to controller
About $600 or so, check solarblvd.com and see what they have . The deep cycle battery is bought at any of your local auto stores or walmart.
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MtnDon
Member
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# Posted: 26 Jul 2012 06:24pm
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Quoting: rugercpl I guess your questions to me will be "what do you consider recreational use", and "what do you intend to need electric for (appliances etc)" and "how much sunlight do you have to work with".
Yes. What you really need is to list all the devices you want to use with the wattage used by each. Separate into 120 VAC and DC of whatever voltage you would like to use. Multiply each by the number of hours of use. That gets you the watt-hours. You need the total for a typical day. Sometimes it's easier to average a weeks worth if use can vary day to day.
Once that is known then the amount of storage can be calculated and then the number of PV modules required.
There is a link to a calculator HERE.
IMO, a 15 watt solar panel is only useful to maintain the charge in a full battery. It will do very little to recharge a system. We've had a successful off grid system for over three years. Things like crockpots can be used off grid but you have to watch when you use it. We use a small one, 100 watts, 120VAC. Generally speaking the use of anything that uses a resistance heating element will be found to be very big power users. Refrigerators also use large amounts of power unless they are one of the ones specially made for off grid use. Standard energy star electric refrigerators can be used but will require a PV system that will likely be much larger than you imagine. A 10-12 cu ft common brand energy star fridge/freezer can use 800 watt/hours a day according to the EnergyStar ratings.
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GomerPile
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# Posted: 27 Jul 2012 01:42pm
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My opinion is to start with the assumption that anyone can rig up a 12V solar system with a panel, charge controller, and a battery. Its simple, very low cost, and reliable. Backup or high demand power is possible with any portable inverter/generator (EU2000i is a good one) that can either power stuff directly, or charge batteries.
As you make your list of stuff you need to live, google search the ways that you can do it with 12V powered appliances. I did the same excercise years ago and discovered that the only thing that won't run directly from 12V is a microwave...so I have a 1000W inverter for that.
My system is 150W panels, nice Xantrex charge controller/monitor, and 200 amp hours worth of $60 walmart deep cycle batteries. Its been running for almost 3 years now. I run lights, fans, small fridge (sometimes), water pump, laptop, cell phone booster, DSL modem, water heater, microwave (sometimes). I recently began full time living in the cabin with this system.
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rugercpl
Member
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# Posted: 27 Jul 2012 05:14pm - Edited by: rugercpl
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What water heater system are you using? How many batteries is that?
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GomerPile
Member
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# Posted: 27 Jul 2012 09:27pm - Edited by: GomerPile
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Assume ur asking me....if not sorry  . Just a plain rv hot water heater that runs on LP. It uses 12v for control power. Honestly if I had to do it over I would have spent the extra money for on demand. When the unit is on it draws about .75 amps and takes 30 minutes to warm up a tank. Far too much power IMO! It's also a pain to wait for hot water. That said, it does produce warm water almost instantly.
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MtnDon
Member
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# Posted: 27 Jul 2012 10:05pm
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We also used an RV water heater, 6 gallon. Ours though is the older pilot light style. We use it 98% of the time with just the pilot flame burning; the burner itself does not come on at all when the control is set to pilot only. We also added three inches of foam insulation all around the tank, 4 sides and the back end.
When we arrive at the cabin I light the pilot and let the main burner heat the water with the thermostat set to Low. Once it has heated the water I switch the burner control to pilot only. The pilot gives off enough heat to keep the contents of the tank quite hot. Very hot if little hot water gets used during a day. We can both do a navy shower, one after the other, and not run out of hot. The temperature in the tank is lowered quite a bit though. Using a temp and pressure protected shower control we do not have to keep adjusting the temp as the tank temp falls. But we each only use a couple gallons tops, cold + hot.
No electricity used for that model at all. The cabin plumbing is set up much like in an RV; water tank, Shurflo pump, fixtures that minimize water use. We used a 32 x 32 inch shower pan and built it into one end of the bathroom. Walls are FRP sheet. A platic shower curtain is carried in a U-shape track, a la RV shower.
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