off grid cabin, some headway made

[gjk5]

as I had mentioned in previous threads I have an off grid cabin that currently has a pretty much useless 12v system and a decent generator (albeit dangerously wired and setup).

I have some components and have run some of the usage calculators. It has propane heat, fridge, stove so really only lights, tvs, radios, laptops, phone chargers and one coffee cycle a day, and only maybe 10 days/mo 8 months/yr usage.

The calculator says:

Watt Hours Required Assuming Inherent Efficiency Loss:
Watts: 5252

I have an Outback inverter, charge controller, panel, transfer switch (all used), 6500W Honda with elec start (will probably convert to propane), 8x Interstate 232 AH batteries (brand new) and am planning on ordering 4x 250w panels to mount on small pole barn/shop with all this crap inside (so I can get it out of the damn cellar)

any thoughts appreciated.

Oh yeah: if it matters this is in Zone 3 at roughly 9K feet but on a hilltop so pretty damn good exposure.

[mschulz]

The calculator says:

Watt Hours Required Assuming Inherent Efficiency Loss:
Watts: 5252

That is a lot of juice needed. Is that figure daily watts needed or for the 10 days?

[Sunking]

Watt Hours Required Assuming Inherent Efficiency Loss:

That is a huge amount of energy to make with solar. In reality a very small amount of energy for a home usage. Average household uses 25 to 30 Kwh/day. Bu tfor a Stand Alone Solar system is a huge amount of energy which comes with great expense.

You are talking a 48 volt 500 AH battery system that weighs in around 1500 pounds of toxic material legally has to have a permit and yearly inspections by local fire departments and EPA. As for panel wattage minimum requirement is going to be roughly 2100 watts using a 40 amp MPPT. Go cheap with PWM controller and you are looking at 3200 watts of very expensive battery panels.

You might want to rethink this. Battery cost alone are going to be around $5000 initially and higher replacement cost every 5 years. Be careful what you ask for.

[gjk5]

here is where I came up with those numbers:

http://www.wholesalesolar.com/StartHere/OFFGRID/OFFGRIDCalculator.html#applianceTable

I am trying to be generous, here are the numbers I used:

6X60W lights 4hrs/day (I know I can go CFL and save watts but trying to err on side of caution)
3Xsmall LCD @ 150w/hr 4hrs/day (two movies per bedroom on crappy day)
1Xcoffee maker @ 900w/hr .33hrs/day
1Xfan @ 100w 3hrs/day
2Xchargers (phone/tablet) @ 25w 4hrs/day

again: infrequent use (MAYBE ten days per month, 4-5 days at at time, 8 months per year), approx 1500 sq ft cabin, 3 bed, 1.5 bath and I have a good generator that I am not afraid to use, would just like to be silent/clean/solar most of the time.

Also: already have 1K pounds of batteries (8X232AH GC's), Outback inverter/mppt (60 watt?)/panels/fuses/transfer switch.

As far as I know there is no such thing as "inspections" for this sort of setup around here either. Good luck on them getting there if there are I guess.

[mschulz]

6X60W lights 4hrs/day (I know I can go CFL and save watts but trying to err on side of caution)
3Xsmall LCD @ 150w/hr 4hrs/day (two movies per bedroom on crappy day)
1Xcoffee maker @ 900w/hr .33hrs/day
1Xfan @ 100w 3hrs/day
2Xchargers (phone/tablet) @ 25w 4hrs/day

.

1800 watts for movies? Might want to rethink that one. Your lights are 1440 of your load, use cfl or LED at 10 Watts saves you 1100 watts. You need a power diet if you even want this to make sense.

At $4.00 per gallon, .5 gal / hr burn rate in that generator, run it for 6 hours / day = $12/ day * 10 days/mo= 120 / mo * 12 months = $1440.00 / year. How much did you spend on batteries?

You have 232 @ 48 volts = 11,136 watts of which you can only use 2227 of it to keep you at 20% Discharge. With your gear, you need to shed 3000 watts per day or run your generator.

Just my $.02

[gjk5]

1800 watts for movies? Might want to rethink that one. Your lights are 1440 of your load, use cfl or LED at 10 Watts saves you 1100 watts. You need a power diet if you even want this to make sense.

At $4.00 per gallon, .5 gal / hr burn rate in that generator, run it for 6 hours / day = $12/ day * 10 days/mo= 120 / mo * 12 months = $1440.00 / year. How much did you spend on batteries?

You have 232 @ 48 volts = 11,136 watts of which you can only use 2227 of it to keep you at 20% Discharge. With your gear, you need to shed 3000 watts per day or run your generator.

Just my $.02

I have two kids and a wife to keep happy, keep them cooped up for a day or two and I need them entertained (and as I said WORSE CASE SCENARIO)

Also said I can do CFL's (worse case scenario anyone?)

Gallon, Schmallon. This is not about money (why can all the solar people not get that?), this is about convenience. I can AFFORD to run that generator as much as I need to, but it is a pain in the ass (and using gasoline sucks). I spent $980 on batteries if that really matters. Also stated I would convert to propane on the genset.

I never once mentioned cost as an issue in any of my posts, just not sure why everyone assumes that it is about the dollars. I want clean, convenient, quiet, and easy. I could easily haul a few hundred gallons of gas up there every season and run that damn genset all the time, but it's not what I want.

If you MUST equate it to dollars I planned on spending about $3K on this system to start, by all accounts I will get 4-5 years out of these batteries so an additional $2kish/decade. So theoretically $3K to start, $1K year 5, $1K year 10, that is $5K over 15 years for power, who gives a ****? Any way you slice it it is better than me going down in the dark to pour gas in a hot generator right? If I really wanted to I could buy a Generac 14K genset and get a bigass propane tank, that is not what I want.

your math is wrong on the gen usage anyway: even running it that way ($12/day/10days/mo), I use it MAX 8 months a year so that is less than I spent on batteries (and again GENEROUS WORST CASE SCENARIO)

I really do not want to argue with folks, just want solar power when I can get it and auto switching to genset when I must.

[SunEagle]

How were you going to wire those 8 batteries?

The best way would be all in series to get a 48volt 232Ah system that can safely yield about 2800 watt hours daily. You can wire them as a 24volt system and get the same watt hour output but you then run the risk of charge/discharge imbalance and a lot more time to care for the system. Forget about making a 12volt system it is just too many parallel connections.

If you use more than 2800 watt hours daily you run the risk of shortening the battery lifespan.

Depending on where you live the 1000 watts of panels can generate enough to recharge your batteries with 4 to 5 hours of good sunlight. If you get less than 4 you start to get into a charge deficit and may use more than can be put back into the batteries. So in the Winter and Fall you may get only 3 hours of useful sunlight which will not be able to charge your batteries properly. Also that 1000 watts is also the minimum wattage needed to charge those 232Ah batteries.

You mentioned an Outback inverter and charge controller. Is that one or two items? You will certainly need a 48 volt inverter and a 30A MPPT charge controller so let us know if that is what you have.

If you can keep your daily usage to that 2800 watt hour your system should work. If you use more watt hours then you will need a bigger battery system and if you get less sunlight you will need more panel wattage. At least you have a generator which is a must for a battery system.

[gjk5]

How were you going to wire those 8 batteries?

The best way would be all in series to get a 48volt 232Ah system that can safely yield about 2800 watt hours daily. You can wire them as a 24volt system and get the same watt hour output but you then run the risk of charge/discharge imbalance and a lot more time to care for the system. Forget about making a 12volt system it is just too many parallel connections.

If you use more than 2800 watt hours daily you run the risk of shortening the battery lifespan.

Depending on where you live the 1000 watts of panels can generate enough to recharge your batteries with 4 to 5 hours of good sunlight. If you get less than 4 you start to get into a charge deficit and may use more than can be put back into the batteries. So in the Winter and Fall you may get only 3 hours of useful sunlight which will not be able to charge your batteries properly. Also that 1000 watts is also the minimum wattage needed to charge those 232Ah batteries.

You mentioned an Outback inverter and charge controller. Is that one or two items? You will certainly need a 48 volt inverter and a 30A MPPT charge controller so let us know if that is what you have.

If you can keep your daily usage to that 2800 watt hour your system should work. If you use more watt hours then you will need a bigger battery system and if you get less sunlight you will need more panel wattage. At least you have a generator which is a must for a battery system.

I was planning on 24v, but not opposed to 48v. I live in W. CO, we get good sunlight and the location is great for it. I will have to look at my pics and notes on what I have for the Outback, it was a complete system I bought from a guy when he sold his cabin.

I do not mind if the gen has to kick in on heavy use days, it is what it is. I just cannot deal with the current situation.

Any thoughts on converting gen to propane? Looks easy and is certainly cleaner and easier than gasoline.

[SunEagle]

I was planning on 24v, but not opposed to 48v. I live in W. CO, we get good sunlight and the location is great for it. I will have to look at my pics and notes on what I have for the Outback, it was a complete system I bought from a guy when he sold his cabin.

I do not mind if the gen has to kick in on heavy use days, it is what it is. I just cannot deal with the current situation.

Any thoughts on converting gen to propane? Looks easy and is certainly cleaner and easier than gasoline.

You might want to check a website called PVwatts Calculator "pvwatts.nrel.gov". There you can get a rough average estimate of "useful" sunlight for your area code. That will help determine if you have enough panel wattage to recharge the batteries.

I know that Honda have conversion kits for some of their generators. Maybe check with a local dealer to make sure yours can be safely converted.

[Sunking]

I will help because you are now aware of the expense.

So help me help you. Here is what I do know, or at least I think I do.

1. Western Colorado? Have a zip code or at least a town name to look up Solar Data?
2. Daily Kwh usage = 5 Kwh? Or something else?
3. Sporadic usage? OK this is a big if thing. You say over a year will get 8-months but no more than a week at a time? If you will be there more 3 days or more in a visit, it is a full time system.

Clear that up for me and I can give details. Right now looks something on the lines of:

Panel Wattage = 1800 to 2200 watts, location dependent
48 Volt Battery Capacity in Amp Hours = 500 AH
MPPT Charge Controller Minimum Amps = 40 amps if below 2000 watts, 80 amps otherwise.
48 volt 100 amp AC charger.
48 Volt TSW Inverter = TBA

Go price that out and see what that works out too. You might want to trim down daily usage.

[gjk5]

I will help because you are now aware of the expense.

So help me help you. Here is what I do know, or at least I think I do.

1. Western Colorado? Have a zip code or at least a town name to look up Solar Data?
2. Daily Kwh usage = 5 Kwh? Or something else?
3. Sporadic usage? OK this is a big if thing. You say over a year will get 8-months but no more than a week at a time? If you will be there more 3 days or more in a visit, it is a full time system.

Clear that up for me and I can give details. Right now looks something on the lines of:

Panel Wattage = 1800 to 2200 watts, location dependent
48 Volt Battery Capacity in Amp Hours = 500 AH
MPPT Charge Controller Minimum Amps = 40 amps if below 2000 watts, 80 amps otherwise.
48 volt 100 amp AC charger.
48 Volt TSW Inverter = TBA

Go price that out and see what that works out too. You might want to trim down daily usage.

thank you for the response:

1: roughly Collbran CO 81624
2: I can slim that a good bit with better lights, but that is what the calculator came up with worst case
3: 8 months of useable time, most of it 3 day weekends with family, 3-4 hunting trips of 5-7 days, do not care if I have to lean on generator

batteries and system components I already have, the panels are the only thing I still need (and shop to get all of this out of basement)

I am just done hauling gas and pouring into the generator at 11PM, I want some "set it and forget it" time

[russ]

I am just done hauling gas and pouring into the generator at 11PM, I want some "set it and forget it" time

So you choose batteries?

[Mike90250]

I am just done hauling gas and pouring into the generator at 11PM, I want some "set it and forget it" time

So you choose batteries?

Bending over, checking electrolyte, adding distilled, monitoring state of charge, is the sun up, can I use the toaster yet. 3 days of rain and the generator won't start... Please sir, may I have some more ?
OK
checking connections. repairing connections the electrician did, more water for the batteries, cleaning the nasty grunge off the battery caps.

But wait, there's more..... Washing the panels off, why does breaker #2 always trip in the combiner box on cold days (bad breaker, swap that out)

[inetdog]

Bending over, checking electrolyte, adding distilled, monitoring state of charge, is the sun up, can I use the toaster yet. 3 days of rain and the generator won't start... Please sir, may I have some more ?
OK
checking connections. repairing connections the electrician did, more water for the batteries, cleaning the nasty grunge off the battery caps.

But wait, there's more..... Washing the panels off, why does breaker #2 always trip in the combiner box on cold days (bad breaker, swap that out)

But at least it is quiet. The loudest noise will be you talking to yourself or swearing angrily.

[paulcheung]

To the OP, Change the lights to LED or CFL, you reduce your watts to 3 to 4KWh. I think you can get away with 1500 watts panels, just get 6 x250 watts panels, and wire the batteries in 48 volts, 2800 watt hours battery is a good amount since you don't use the battery during the day, also you not use it 24/7 it will be ok. Just prepare these batteries might not last you 4 to 5 years, but should last you at least 2 to 3 years if you take care of them.

When you get rainy days you just charge your battery with the generator.