Hunting cabin help... Solar off grid Any ideas?

squzzie · September 2014

Location 3000ft elev. south eastern Pennsylvania

My idea
2 24v (2 set of 4 6v golf cart batteries exide) battery banks
2 500w mono panels
charge controller
1250w Continuous modified sine wave inverter directly wired into house.

Usage
small rv refrigerator norcold 811 tri-power (Liquid Propane-AC)
Max of six 13watt lights
television
satellite box
coffee maker
charging small devices like cellphone and laptop

will this be sufficient???
Thank you

Cariboocoot · September 2014

Re: Hunting cabin help... Solar off grid Any ideas?

Welcome to the forum.

Loads are the place to start for such a plan, and your loads are only an item list at this point. So let's look at them one at a time:

small rv refrigerator norcold 811 tri-power (Liquid Propane-AC)

First warning: don't use the 120 VAC option because all it does is replace the heat of the propane with an electric element. Big Watts and big Watt hours. It may require a 12 VDC source all the time to operate controls.

Max of six 13watt lights

Well 6 * 12 is 78 Watts which is easy to supply, but the amount of time they are used makes a big difference. Two hours? Four? Some now and some again? This can make for an unpleasant variable as 78 * 24 maxes at 1872 Watt hours!

television

TV can draw all sorts of different Wattage depending on what one and what the settings are. Example: I adjusted my 40" LCD video settings and dropped 100 Watts. How long you have it on for - another variable.

satellite box

Well I have a sat Internet set-up with modem, router, VOIP phone etc. Burns away at about 50 Watts and in the course of a day uses as many Watt hours as the full size refrigerator. We turn it off at night.

coffee maker

Propane is your friend. It can take a sizable system just to fire up one of these because it's usually a 1500 Watt heating element.

charging small devices like cellphone and laptop

Unpredictable loads. But you probably have them already so ... get a Kill-A-Watt and try it out on these. See how much they draw (Watts) and how much they consume to recharge (Watt hours).

And don't buy anything yet! Until you know how much power you need all equipment will be a guess with a 2/3 chance of being wrong. For example a battery bank of eight 220 Amp hour 6 Volt GC2's is 440 Amp hours @ 24 Volts and that's quite a bit of power (about 4.5 kW hours). So much so that 1000 Watts of panel may not recharge it.

For what it's worth my system in my sig line runs just about everything I need. Notice it has less battery than you propose, but more panel.

Cariboocoot · September 2014

Re: Hunting cabin help... Solar off grid Any ideas?

Oh and avoid the MSW inverter. Some of the items you have listed are known to be incompatible; battery chargers and TV's for example.

squzzie · September 2014

Re: Hunting cabin help... Solar off grid Any ideas?

yes u are correct about fridge
lights very little use maybe say total time per bulb per day is about 15 minutes if that
tv equipment pulls about 200watts for about 6 hours a day
these are heavy estimates i only stay about 2 days a week
using lp for fridge now and harbor fright 12v 45watt 3amp amorphous kit and analog 300w inverter. watching tv about 4 hours and running 2 lights every other evening about 4 hours. been holding up fine 1 12v equipment battery drops to about 11.4 volts before bed every evening back up to 12.6 late afternoon. Being very conservative though.

Oh and coffe pot is rated at 6amps for about 1 minute its a single cup pot..

I also have lp lights for evening and lp stove

other applience used rarely say a minute a day is a bread toaster

I understand load resistive devices consume alot of power.

Cariboocoot · September 2014

Re: Hunting cabin help... Solar off grid Any ideas?

squzzie wrote: »

yes u are correct about fridge
lights very little use maybe say total time per bulb per day is about 15 minutes if that
tv equipment pulls about 200watts for about 6 hours a day
these are heavy estimates i only stay about 2 days a week
using lp for fridge now and harbor fright 12v 45watt 3amp amorphous kit and analog 300w inverter. watching tv about 4 hours and running 2 lights every other evening about 4 hours. been holding up fine 1 12v equipment battery drops to about 11.4 volts before bed every evening back up to 12.6 late afternoon. Being very conservative though.

Oh and coffe pot is rated at 6amps for about 1 minute its a single cup pot..

I also have lp lights for evening and lp stove

other applience used rarely say a minute a day is a bread toaster

I understand load resistive devices consume alot of power.

Well a 12 Volt battery being taken down to 11.4 Volts is not long for this world.

200 Watts of TV * 6 hours = 1200 Watt hours, which is quite a lot off-grid. For example that's 100 Amp hours on 12 Volts excluding losses. That there would consume half of a 220 Amp hour 12 Volt system. Frightening, isn't it?

Coffee pot pulling 6 Amps @ 120 VAC is 720 Watts. Not as bad as the full-size kettle, but more than half as much! The good thing about these is that they don't need to be on very long. It's supplying the power when they are on that is the trick: 750 Watts on 12 Volts is 60 Amps (ignoring losses) and that's some fairly significant current. More than 25% of a GC2's capacity.

The other question to ask: what happens if you lose your electric? How much of a problem would that be? Got a generator for back-up?

From your initial equipment list it looks to me like the thing you'd most want to do is reduce the battery bank to a single string of four GC2's (220 Amp hours @ 24 Volts - halve all 12 Volt current readings mentioned above) and replace the inverter with a sine wave one which won't cause trouble for the cell charger or throw interference on the TV.

squzzie · September 2014

Re: Hunting cabin help... Solar off grid Any ideas?

Cariboocoot wrote: »

Well a 12 Volt battery being taken down to 11.4 Volts is not long for this world.

200 Watts of TV * 6 hours = 1200 Watt hours, which is quite a lot off-grid. For example that's 100 Amp hours on 12 Volts excluding losses. That there would consume half of a 220 Amp hour 12 Volt system. Frightening, isn't it?

Coffee pot pulling 6 Amps @ 120 VAC is 720 Watts. Not as bad as the full-size kettle, but more than half as much! The good thing about these is that they don't need to be on very long. It's supplying the power when they are on that is the trick: 750 Watts on 12 Volts is 60 Amps (ignoring losses) and that's some fairly significant current. More than 25% of a GC2's capacity.

The other question to ask: what happens if you lose your electric? How much of a problem would that be? Got a generator for back-up?

From your initial equipment list it looks to me like the thing you'd most want to do is reduce the battery bank to a single string of four GC2's (220 Amp hours @ 24 Volts - halve all 12 Volt current readings mentioned above) and replace the inverter with a sine wave one which won't cause trouble for the cell charger or throw interference on the TV.

Yes I ahve a generator/inverter honda i2000 for back up i was looking to possibly or maybe you will know if there is an inverter that also supports charging he 24v battery bank from either a 120v or 12v supply when the generator is running?
I also want to have a little room say for maybe and additional tv for bedtime and maybe say a window fan for hot summer evenings.

Thanks agian
Yes I will get an actual usage and load reading tonight.

westbranch · September 2014

Re: Hunting cabin help... Solar off grid Any ideas?

If you were at 12v you could run some LEDs (ie MR 16 type track lights) direct on 12v, no inverter needed.

Cariboocoot · September 2014

Re: Hunting cabin help... Solar off grid Any ideas?

squzzie wrote: »

Yes I ahve a generator/inverter honda i2000 for back up i was looking to possibly or maybe you will know if there is an inverter that also supports charging he 24v battery bank from either a 120v or 12v supply when the generator is running?
I also want to have a little room say for maybe and additional tv for bedtime and maybe say a window fan for hot summer evenings.

Thanks agian
Yes I will get an actual usage and load reading tonight.

Oh I know inverters that will charge from the generator's 120 VAC output. They come with a large price tag though. For a small system it is cheaper to buy a stand-alone charger like an Iota: the combination of inexpensive inverter & separate charger works out less. Example:

Samlex 2kW sine wave 24 Volt inverter http://www.solar-electric.com/inverters-controllers-accessories/inverters/sasiwain1/samlex-pst-series-pure-sine-wave-inverters/samlex-pure-sine-wave-inverter-pst-2000-24.html $643 plus Iota 24 Volt 25 Amp charger http://www.solar-electric.com/batteries-meters-accessories/bach2/bach1/ioten25amp24.html $182 total $825

OR

Outback 2.5kW sine wave 24 Volt inverter http://www.solar-electric.com/inverters-controllers-accessories/inverters/ouin/oupooffgrand/outback-power-pure-sinewave-inverter-fx2524t.html $1,633 not including the MATE interface for $300 more.

And you may not need a 2kW inverter either.

Steve961 · September 2014

Re: Hunting cabin help... Solar off grid Any ideas?

When you're going off-grid, energy efficiency is everything. Even if you have to purchase new devices, many times you are money ahead by not having to buy more panels, a bigger inverter, and/or a larger battery bank.

Your TV especially is a power hog. For example, Samsung has a 40" LED TV that typically consumes 30 watts, and a 48" at 38 watts. That alone could save you ~1,000 watt hours from your total.

Blackcherry04 · September 2014

Re: Hunting cabin help... Solar off grid Any ideas?

Outback also has the GFX1424 that is a 24v Inverter / Charger that has a 2000va surge for 30 minutes. It would run every thing you have plus a 40 amp charger and Generator support to allow you to run some bigger loads. They can be had for around a $1,000 plus the Mate, so around $1,300 total. It's one of the few Inverters that I ever found that has it all kinds of flexibility built in that you need when using a small generator.

http://outbackpower.com/index.php/outback-products/inverters-chargers/item/sealed-gfx1424?category_id=448

westbranch · September 2014

Re: Hunting cabin help... Solar off grid Any ideas?

Or as we use a 19" Toshiba with built in video player that uses 19 watts.... and it is an oldie, about 4 years old :-).... their Watt usage drops a bit each year... to meet the ever increasing stricter targets for efficiency rating listing...

mike95490 · September 2014

Re: Hunting cabin help... Solar off grid Any ideas?

Oh I know inverters that will charge from the generator's 120 VAC output. They come with a large price tag though. For a small system it is cheaper to buy a stand-alone charger like an Iota: the combination of inexpensive inverter & separate charger works out less.

But the Iota has a lousy power factor (PF), which means you need a larger generator.
Tradeoff - independent charger & inverter, means one can fail, and the other still works. But the inverter is the charger running backwards, so if the all-in one fails, you have no loads on the battery to drag it down !

Outback also has the GFX1424 that is a 24v Inverter / Charger that has a 2000va surge for 30 minutes. It would run every thing you have plus a 40 amp charger and Generator support to allow you to run some bigger loads. They can be had for around a $1,000 plus the Mate, so around $1,300 total. It's one of the few Inverters that I ever found that has it all kinds of flexibility built in that you need when using a small generator.

Sounds like a plan, if the charger section has a good PF.

Hunting cabin help... Solar off grid Any ideas?

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