I will start off by telling everyone my plans. 

I going to be building approximately a 2500sq ft  Log home use 6x8 logs.  It will have a full basement using ICF's.  I am also going to be installing geothermal.  And I am wanting to encorporate some kind of grid-tied hybrid system using solar and wind.  I live in southern Illinois near Carbondale and from what i have researched it will be a good setup.

My problem is that I am having a had time figuring out how big of a system I need to have a net-zero home.

Any ideas or help would be greatly appriciated


It will also be sitting on 74 acres that is mostly flat farm land surrounding the property with minimal woods.

You may wish to move your post to the "solar and wind power" page.

Well Im also wanting any input on the entire project.   Am i missing something?  I just don't want to get down the road and wish i would have done something different.  Such as,  if someone has a good idea for the roof insulation, or maybe be better to do a grid tie system with battery backup.  Is the battery backup really gonna do me any good with the geothermal.  I don't want to run anything on propane.  so my stove, water heater and everything in between will be electric.  Unless some one can point out how the gas will benifit.  I want to be able to one day go off grid if i want. I don't want to make a $100 mistake and later it take $1000 to fix or redo it.

Those 6*8 real wood logs will have an R-Value of 1 per inch. If you use the wood logs with the narrow side showing and the wide side on the flat, you will get an R-Value of 8 in your walls. You need to decide what R-Values you are going to have in your basement walls and floors, as well as your attic insulation. Once you have all these numbers, calculate your U values. Then find the area of your attic, perimeter walls, windows, and basement walls. Next, finding the degree-days of heating and cooling for your location. Combining all this information, you can figure out how many BTU's you will need to heat/cool your house. Then, knowing how many kWh it will take to make a BTU based on your geothermal system, you can figure how many kWh's you need to produce in a year to heat/cool your house. There are many guides on the internet on how to do these tasks, so I don't see the need to repeat the details here. Add to that how much your appliances will use, off of their labels, and you will have an estimate of your annual electric usage will be.

Also, you can just leave yourself some upgrade room if you don't quite hit the 100% mark right away, there is nothing wrong with slowly adding and building up to it.