building a off grid cabin

[davidb]

Hi. I have been building a cabin in Northern Idaho. I am going to need plenty of advice and sugestions. My kwh/month will be about 320. I have a 10k diesel genset for backup. Im not sure how big of a inverter to buy. I am considering a outback 8048 radian. I looked into AIMS, but the reviews and warranty are not very good. I also would like to get about 10- 310 watt solar panels. The calc map shows about 4.2 hours of sun a day. Considering Rolls batteries, but I dont know how many strings and what size to get. Advice would be greatly appreciated as I dont have any solar knowledge. Thank you... Dave

[Sunking]

Hi. I have been building a cabin in Northern Idaho. I am going to need plenty of advice and sugestions. My kwh/month will be about 320. I have a 10k diesel genset for backup. Im not sure how big of a inverter to buy. I am considering a outback 8048 radian. I looked into AIMS, but the reviews and warranty are not very good. I also would like to get about 10- 310 watt solar panels. The calc map shows about 4.2 hours of sun a day. Considering Rolls batteries, but I dont know how many strings and what size to get. Advice would be greatly appreciated as I dont have any solar knowledge. Thank you... Dave

First you do not get 4.2 Sun Hours year round, that is yearly average. For off-grid you use worse case month of December and for you that is 2.5 Sun Hours.

Batteries are easy to figure out. Based on your daily usage of 10 Kwh/day you need a 48 volt 1050 AH cells. At this capacity will require 2 volt cells like Rolls S-1380, 24 of of them.

As for panel wattage to support 10 Kwh per day is going to be a challenge in your location due to less than 3 Sun Hours in winter month. It will require a 6000 watts. Problem is that would require 2 very expensive MPPT charge controllers. I would suggest 5000 watts and a Midnite Solar Classic 80 amp MPPT controller. In short winter months will require running the generator periodically to make up the shortage.

As for inverter size a 48 volt 1050 AH battery can only support at best is 6000 watts, but I seriously doubt you would need anything that large. You need to do a load calculation to determine maximum power demand. I bet it comes up less than 2000 watts and I think that is a stretch.

[davidb]

Thanks for the info. Looks like those batteries are going to kill me $$$. Dave

[Sunking]

Thanks for the info. Looks like those batteries are going to kill me $$$. Dave

Well any 48 volt 1000 AH battery is going to cost you some bucks. Then in about 5 to 7 years you get to buy them again.

[davidb]

Since you have outstanding qualifications, and a whole lot of posts, Im assuming that you calculated the solar array input to the battery bank when you sized the battery bank. I have NO experience with solar so if you have time, could you show a little math (made easy) for me. I did another energy calc and moved some of the large energy items to the generator load. This got me down to 6800 watts per day. Since Im remote... I dont have much choice. It was hell to delete the Mr Coffee pot. A percolator pot will look good on the wood stove. Thank you. Dave

[russ]

Since you have outstanding qualifications, and a whole lot of posts, Im assuming that you calculated the solar array input to the battery bank when you sized the battery bank. I have NO experience with solar so if you have time, could you show a little math (made easy) for me. I did another energy calc and moved some of the large energy items to the generator load. This got me down to 6800 watts per day. Since Im remote... I dont have much choice. It was hell to delete the Mr Coffee pot. A percolator pot will look good on the wood stove. Thank you. Dave

That is the trick - switching away from electric where possible. Your wood stove top percolator is great as is propane for some uses.

[Sunking]

Since you have outstanding qualifications, and a whole lot of posts, Im assuming that you calculated the solar array input to the battery bank when you sized the battery bank. I have NO experience with solar so if you have time, could you show a little math (made easy) for me. I did another energy calc and moved some of the large energy items to the generator load. This got me down to 6800 watts per day. Since Im remote... I dont have much choice. It was hell to delete the Mr Coffee pot. A percolator pot will look good on the wood stove. Thank you. Dave

Simple use the Stickies

Off Grid Design
Inverter vs Battery Size
Battery Tutorial

That should answer most of your questions. Read them and come back with questions.

[davidb]

The power company has a pole about 600 feet through a heavy wooded area, 50 feet of it on private property. I MIGHT be able to get a line ran close to my house, the go underground for the last 100 feet. A ball park figure is 12-15 thousand. They require a non refundable 750$ deposit for a estimate. Sun king, or anyone else... what is your thoughts? The power company is a co op. Northern lights. I have them where I live now, and only loose power a few days a year. this year was 6 days straight.

[davidb]

Here is my solar option I have attempted to put together use the links provided by Sunking. 48 volt system...12- 310wt panels. 1 classic lite 150 MPPT controller @ 48 volts. 1 Magnum ms 4448pae inverter 120/240 volt with 60amp charger. 30 amp per leg transfer (pretty close to my genset). 16 rolls S550 Batteries. two strings @48 volts. Please tweek for me. I am still looking into options on reducing the house load such as moving the freezer to the below ground root cellar which maintains a temp around 50 degrees.

[Sunking]

Do not use 2 parallel stings. If you need 1000 AH battery, then buy 1000 AH cells.

Then do a cost analyses. Those batteries need replaced every 4 to 7 years. Your battery cost will run you somewhere around 60-cents per Kwh over their lifetime. You rPOCO charges you less than 10-cent for as much as you want with no daily limitations. I think you will find the POCO is the better long term investment.

[davidb]

the big " IF" I can get them to run power to me. @ what cost do you think the POCO to run power is too expensive? Also thanks for taking time to reply and help... Dave

[Mike90250]

My power co wanted $20k per pole, + extras. extra tall, certified poles, I could not supply my own. I needed 7-10 poles. Then tried the underground service route, they wanted 2" conduit laid 24" in special gravel, $800 pull boxes every 100' and an easement, before they would price the cost of pulling wire. Cost to do this on 1/2 mile of driveway was also prohibitive. i figured they didn't want the job, so I'm off grid.

[davidb]

I moved from Mountain Ranch Ca to Bonners Ferry Idaho area. I guess we cannot get away fromcompanies that have no compitition. When I built my Valley Springs house in 1991, PGE ran 600 feet for free.

[davidb]

Mike, I noticed you run your well pump on a timer. I assume you have a holding tank with a booster pump to the captive air pressure tamk(s). How do you keep the water from freezing in the winter? I have to have 1500 watt heaters in the stock tanks @ my present residence and my electric bill in the winter reflects it.

[Mike90250]

Mike, I noticed you run your well pump on a timer. I assume you have a holding tank with a booster pump to the captive air pressure tamk(s). How do you keep the water from freezing in the winter? I have to have 1500 watt heaters in the stock tanks @ my present residence and my electric bill in the winter reflects it.

I pump, to elevated tanks (4, 3,000 tanks) about 160' on a hill, so it's gravity feed. Water lines are 4' deep. Last year, my filter tank (a slow sand filter) iced up, and I put a 150w aquarium heater in it.