Battery and Inverter recommendations...

Dawn:

I hope you haven�t bought that Jacobs.  Although it was considered the Cadillac of its time, that was 50-60 years ago.  It was made for stand-alone operation, not grid tie.  And the �40 Volts� sounds like peak output voltage on a 36 volt system. 36VDC is not a system voltage in common use today.  A good electrical person can make a workable system with a 36V mill, but it is not something a beginner should attempt.  

To stop your head from swimming, just stop thinking about your windmill size, inverter, batteries, etc. Get your site assessment done. When it is done, it will guide you to the right decisions.

Oso

Dawn:
If the people offering to sell you the Jacobs mill are full service installers (offering to sell a complete system to you, and install it for you), by all means get a price from them on a complete, installed system.  But I would still want to compare the price to a similar sized system from other manufacturers/installers. If the Jacobs people are only selling parts of the system (e.g. the wind turbine only, or wind turbine and tower only), it will only complicate the selection of the system components.

You stated earlier that you were considering a system without batteries. I highly recommend that approach. It will save you a lot of money.  I have a feeling that what changed your mind was talking to the Jacobs people.  They probably need a little juice from a battery as excitation current.  If they are only talking about a small battery for this purpose, it is no big deal.  But if they are recommending a large battery bank to you, to provide this excitation current and �power during power outages�, they are increasing the cost of your system.

If you are firm on the Grid tie only approach, it is one of your known �design criteria�, at this point. The other is that you want 900-1100 kwh per month. Wind power is not a design criteria, it is merely one of the available resources to achieve your criteria.

But, you are way ahead of yourself, trying to select components for a system, when you are not sure of your resource. Component selection should be step 3 or 4 of the process. So, lets back up and start at the beginning.

Step one should be the preliminary site assessment. In your state, they have a listing of qualified people to perform this function. I would look for either an independent consultant, or a full service installer that handles both wind and solar systems. This site assessment is a prerequisite for participation in the cash-back awards or �rebates� offered in your state.

Whether the person doing the preliminary assessment becomes your �expert� for further steps, or whether you chose someone else for the next steps, will be up to you.

Wind and hydro are very site specific resources. Solar has some site specific concerns, but not anywhere near the wind and hydro concerns. So, a good site assessment is necessary to determine which resource or combination of resources will be the most economical for you. So far, you are just assuming that wind is your answer and it will work. (Maybe it will help you to think of this as your alternative energy system, rather than your wind system.)

The preliminary site assessment will provide you with good educated guesses as to what resource or resources will work on your site. And it will provide you with ball park guesses of the costs.

Step 2  If the preliminary assessment does not yield �black and white� results, further studies and/or research may be required. With wind, wind studies may be called for.

Step 3 is preliminary system design(s) and economics.

Step 4 is detailed design and final component selection.

If a person thinks they have a lot of wind, is thinking small (a few hundred watts) and the total investment is small (let us say $2,000 or less), they can afford to jump directly to component selection. Or sometimes, the expert they are talking with makes that jump for them. It can appear to be a two step process instead of 4.

However, you are thinking a medium size, 3 kw class, wind system. It is a larger investment of $15,000-$25,000 installed. It could run more, depending on a few variables, but particularly your site configuration. And lastly, any mistakes can really drive up the cost.

For �ball park economics� I have selected one of the currently available 3kw machines, assumed a $20,000 installed cost and used a 15 cent per kwh price. Use them for an �order of magnitude� comparison.

15 mph  850 kWh per month  13 years
12 mph  525 kWh per month  21 years
10 mph  325 kWh per month  34 years
8 mph  160 kWh per month  69 years

I want you to look at how these minor changes in average wind speed cause a major difference in the kwh produced, and in the length of the payback period. This is why the wind resource should  be confirmed, before going further.
 
If your site falls at either of the two extreme ends, it is easy. If your site has the something near the 15mph winds you are hoping it has, you can go for it. At 8mph end, it isn�t worth doing, and you should be thinking solar, or possibly hydro.

The complexity will really come in to play, if your wind speed falls �somewhere in between� 8 and 15 mph. It may be a hybrid system of wind and solar, or it may be up sizing the machine class, to achieve better numbers.

Sometimes an expert with his local knowledge, can make an on the spot recommendation, after looking around the site during the site assessment.  Other times he may suggest wind studies to firm up the numbers on the wind speed. This will allow him to better specify size and/or mix of the system for you.

So, unless you can afford a $20,000 mistake, you need to follow this process, and confirm the exact wind resource. Are you willing to risk 20 grand or more on an un-validated wind speed map ? (I won�t risk it, even with a validated map)

After an �expert� gives you the size mix and economics of the system (or 2-3  alternative systems) you can make your selection of the final system design, based upon how well it meets your design criteria and the economics.

It would be at this point that discussion of exact components really comes into play.  But your selected  �final design system� will have ruled out many of the variables that are currently confusing you. Even for experts, that final design concept pretty much drives most of the decisions on exact sizing, voltages, etc., so you don�t even have to get participate in those if you do not want to.  

Here is the �Small Wind Electric Systems, a Wisconsin Consumer guide� http://www.eere.energy.gov/windandhydro/windpoweringamerica/pdfs/small_wind/small_wind_wi.pdf

It is really a DOE guide with cover, wind map,  and Wisconsin Contacts added to it.  As a package it is excellent, one of the best I have seen.  I do not know if you have seen it.  Please note that the wind map it contains is a 60 meter (196 feet) wind map. It also discusses some of the other people you should be talking with, including zoning, the utility, etc.

Oso

I am happy to try helping and happy that you have the process started.

I would like to ask if you wouldn't mind giving us an update on your progress once in a while. I for one, would be interested and there maybe others on the board that would be interested in following a project like yours from beginning to end.

Good luck,

Oso