Off-grid cabin, looking for options

caleb · October 2016

I've been reading for weeks and I don't feel like I know much more than when I started. I recently bought an off-grid cabin that was sold as having a "solar system". I should have done more due-diligence, but didn't. When I got in to it, I found out it has a 35W trickle charge panel hooked up to bank of deep cell automotive style batteries. The panel doesn't keep up with the discharge on the batteries. It was sold with two backup generators, a 1000 Honda (not the EU series) and a EM3500 Honda. Right now most of the cabin is all DC powered and there's three outlets that are AC powered by the generators when they're running. I'm finding I have to pretty much run one of the generators all-day to keep the batteries charged. I'd like the cabin to be all AC powered.

So here I am. My demands currently are pretty small. I have a dozen lights, an RV style water pump, and a small microwave (one of the outlets wired to the generators). I plan to add a few other electronics (a TV ~135W, a small wireless router ~20W, and a few lamps). I've already bought LED bulbs to swap out once I switch over to AC, they're 9W each. My stove and refrigerator are both LPG, I also have a couple wall lamps that are LPG, and I have a wall heater that's LPG (I also have a wood burning stove for serious heat).

I've been looking at the off-grid kits (I don't think I know enough to piece something together myself right now). I would like to get a nice inverter and charge controller, something larger than I need right now so if I need to I can grow a bit without re-spending money knowing I'll spend a little more upfront than is currently necessary. It seems the kits I keep getting drawn to are in the 3500W range such as https://www.solar-electric.com/outback-power-off-grid-kit-1590-watts.html or the "Adventurist" kit from http://www.solarhome.com/offgrid-hyper-x--solar-kits.html. I'm not 100% certain, but I believe this comes down to Outback vs. Schneider. The Schneider kit comes with everything, including racking. I was hoping to do a similar kit as those but with only a couple (2) panels for now and no batteries. Would that be a waste? I've got a budget of around $5K right now and plan to add on to it (batteries, more panels, and a nice generator) after winter.

Since I've only got a couple weeks before my cabin will be snowmobile access only, I also have thought of doing a nice generator now (like the Kohler 12RES, I know that's way overkill, may do the 6VSG) that's made to run off-grid since I don't think it will take a lot to get one installed (may be totally wrong) and then doing the solar system in the spring.

What's everyone's thoughts? What am I missing? Am I crazy to consider doing the genset first and then dealing with the solar later?

softdown · October 2016

Wait until spring on the solar. It's a bit late but I feel like you are trying to do too much with one post.

Photowhit · October 2016

Lots of questions;

Do you have good in obstructive southern exposure?

Would you like to do more with solar than the items listed?

How much energy and how often is the water pump run?

Age of the batteries? Really shouldn't need to run the Gennys all day to keep them charged!

BTW- If you don't intend to rent this out, this should qualify for a 30% tax credit off any tax liability you have! at least for the next couple years.

Thom · October 2016

How many amps is your battery charger that is running off the gen ?

Thom

Thom · October 2016

How many battery's is your bank of batteries?

Photowhit · October 2016

Thom said:

How many amps is your battery charger that is running off the gen ?

Yeah, I wasn't thinking, perhaps you don't have a battery charger designed for deep cycle batteries!

Thom · October 2016

Or using the 12v output from the generator? His tv uses a lot of power 135w wow . We run our dsl box off 12 v so the inverter is on only at night.

caleb · October 2016

Thanks for the responses. I'll try to answer all the questions. My southern view is spotty, too many trees. I have a couple spots (one ~6' wide strip the length of my roof, another on the ground that I could probably do ~8 panels) that have sunlight most of the day. I could also remove trees if needed to, but don't want to unless I find it's required. My power requirements are small, I don't plan to really do anything more. This is just a weekend cabin, used maybe three weekends a month. The pump uses 100W, it used very little. The largest use is while we're showering, otherwise it's only real short bursts (washing hands, brushing teeth, etc). I'm not sure on the age of the batteries. I have 8 and all of them are 135ah each. I would think they should last me a lot longer than they do, I've been leaning towards them being shot, but have thought about the charger not giving enough juice. The charger is just an automotive style (so 15 amp). It has a setting for deep cycle batteries, but I think having all 8 hooked up is what it probably can't handle.

No plans to rent. The tax incentives are really what has me coming back to just doing the solar this year. I believe next year it drops to 26%, still better than nothing I would get with the generator.

I actually don't have the TV yet. I've looked at a few and found they're anywhere from ~90W to 135W, so was using that as worse case.

Thanks again

softdown · October 2016

It is possible to find a welder who will make very affordable 1/8" angle iron racking. Racking isn't as big a deal as some believe.

Photowhit · October 2016

caleb said:
I actually don't have the TV yet. I've looked at a few and found they're anywhere from ~90W to 135W, so was using that as worse case.

Look closely, I have a 55 inch, (LG?) that uses 70 watts in the eco mode...

You might be looking at the back of the set, which is the max draw. Look at the energy saver and do the math backwards, some will say what they use in eco mode.

caleb · October 2016

Photowhit said:

caleb said:
I actually don't have the TV yet. I've looked at a few and found they're anywhere from ~90W to 135W, so was using that as worse case.

Look closely, I have a 55 inch, (LG?) that uses 70 watts in the eco mode...

You might be looking at the back of the set, which is the max draw. Look at the energy saver and do the math backwards, some will say what they use in eco mode.

Thanks, yeah that's exactly what I was doing, looking at the back of the set.

Thom · October 2016

8 @ 12v batteries in a 12v system is tough to maintain and charge .

Thom

mike95490 · October 2016

Get a honda eu2000 for the winter and run it when you need power. Also get air filters, and oil for changes. Take the winter to properly plan your system, and built it in spring/summer
Be thinking about eventually graduating to a 24V system using 4, golf cart batteries in series, an inverter, and AC charger, 24V 30A ballpark. Solar may or may not be useful.

westbranch · October 2016

your best charging option is to disconnect those batteries and charge them singly... NUMBER them and record the START voltage, the END voltage and then the voltage after they have sat for 3 hours without a load or charge, this is the RESTING voltage... post them here. Also for each battery record and post the SG for each battery before and after charging...

enjoy...

Thom · October 2016

48 cells to check fill and record ! Oh what fun

thom

softdown · October 2016

Good Rule of Thumb for deciding Voltage:
12 volt....for less than 1000 watts
24 volt....for 1000 to 2000 watts
48 volt....for 2000 watts and above

I don't know how folks manage anything resembling a modern life with less than 600 watts of PV. PV is cheap these days and you have eight 135Ah batteries. If these are 12 volt batteries, it would be hard to use them properly without a 48 volt system.

I have yet to read someone regretting that they went with a higher voltage system. The electrical lines suddenly double their capacity for one thing. Panels can be wired in series as well.

mike95490 · October 2016

Thom said:

48 cells to check fill and record ! Oh what fun

Another good reason to avoid parallel banks !

Off-grid cabin, looking for options

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