first post, great community

[BullCreek]

Long time lurker - first time poster.  I hope some day to have the time to fully explore many of the projects I've read about here (particularly the wind generators as we have alot of wind in the area), but in the mean time, my employer is a wireless ISP and I've been trying to get them thinking about using renewables to power some equipment we'd like to put in fairly remote locations.  They've given me a modest budget of ~$2000 to experiment.

The equipment uses 12v and I've tested it at around 4A fully loaded (say 50W 24 hours a day worst case).  Originally, I was thinking solar only, but lots of time in the winter, the fog will set in for days on end - so that got me thinking hybrid - solar and wind (there are several commercial wind farms in the surounding area so we have good wind as well as sun).

One key requirement we'd like is to have a charge controller that can tell us battery status and other statistics like amp hours in/out of the batteries over our network (i.e. a charge controller or some aux device that can be plugged into the serial port on the router and then tied into our network management software via a bit of clever programming).  That way, if the battery bank looks like it is going down, we can send someone out to car charge it hopefully before the network dies.

After looking around, the TriStar TS-45 (http://www.affordable-solar.com/morningstar.html) seemed like the perfect candidate as it isn't too expensive, and it has a serial port that does MODBUS which we can interface into our router management software.  Does anyone have experience with these controllers - are they any good?  Is there a better solution that provides similar functionality?

For the wind part, I was hoping there was a cheap "off the shelf" turbine we could use.  The AirX fits the price requirement but everything I've read about it says that even in a strong wind, it doesn't generate enough power to matter and is unreliable to boot.  For the prototype, I have a machinist friend that could probably help me build a small turbine similar to those some of you have and that scoraigwind writes about, but I suspect my boss will complain about the amount of time it takes me to complete it and the others that would follow if the project is successful.  Are there any good commercial options available?  Assuming proper shop and competence, how many hours does it take to build one of Hugh's 4ft turbines - the first time - and subsequent times?

For a hybrid system, could I get by with just one TS-45 charge controller, or would I need 2 (solar and wind) or even possibly 3 (solar, wind, dump load for wind).  FWIW, the equipment we use already has low voltage disconnect.  Also, does anyone make a combined solar/wind charge controller that does MPPT and has a serial port?  Rather than using several small ~80W panels I might prefer to use one large ~160W+ one - but all the large ones are much higher voltage than my 12v batteries which entails MPPT for efficiency no?  I guess it may be moot, as from what I read, you can't even get the big panels anymore due to supply shortages.

Lastly, if you think the whole idea sounds stupid or overly ambitious - please tell me before I spend any money.  I've gently hyped it to the boss - but he'll never let me live it down if I spend time/money on it but can't get it working fairly reliably.

Thanks, --J

[BT Humble]

Here in Australia, many of the remote mobile (cell) phone stations are solar powered.  If you can get in contact with a technical person from one of our local phone companies maybe they can give you some advice about exactly what kind of problems you're likely to run into?

http://www.telstra.com.au

http://www.vodafone.com.au

http://www.optus.com.au

I know that theft of solar panels is a big problem.  One guy who I was talking to over my Xmas holidays said that he worked for Telstra, and at one remote site they mounted the panels 100' up a tree - only to have them go missing 2 months later.

My brother-in-law works for a company which maintains remote comms sites (i.e. he isn't involved with actually setting them up, just supplying power to them) for Vodafone, I'll ask him if he's interested in corresponding with you.

BTH

[BullCreek]

Thanks.  I'll check those links out.  Most commercial telecom equipment is 48v I think, but the the stuff we use is basically an embedded PC running Linux, hence 12v.  I had already thought about mounting the panel(s) and the batteries up the tower a good ways to keep cattle and varmits from destroying them, but hadn't thought about theft.  It might not be a problem here - because of both the remoteness, and I think most land owners in the area shoot first and ask questions later if they see someone they don't know on their property.  :-)

[Ungrounded Lightning Rod]

Originally, I was thinking solar only, but lots of time in the winter, the fog will set in for days on end - so that got me thinking hybrid - solar and wind

Fog?  Or overcast?

Solar and wind tend to work well together because stormy weather blocks light but provides plenty of wind, while calm days are normally clear.  But fog is usually associated with calm.

(Fortunately, fog doesn't block as much light as heavy overdcast.  Instead it tends to diffuse it so it's coming from all directions but much of it is still there.  So your panels may produce useful amounts of power even with fog present.)

(there are several commercial wind farms in the surounding area so we have good wind as well as sun).

That's a good indication that you have strong prevailing winds a significant fraction of the time.  B-)  You'll need to be sure you're not in a windshadow, of course.  But if you're siting radio equipment you're probably already on a local high spot.

You'll want to make sure your wind genny's blades don't interfere with your signal, producing ghosting/selective fading.  Easy way to do that is to have the turbine and antennas at different heights, so the turbine blades are not in a strong part of the antennas' patterns.  Easy to do on a common tower.

On a common tower I'd use a low-vibration prop such as a 3-blade rather than a 2-blade, to minimise shaking of the comm electronics.  The vibrations are low frequency, so they shouldn't produce any significant phase-modulation of your signals by moving the antenna unless the tower is being shaken apart.  (They should be less of a problem than wind-howl.)

[finnsawyer]

Put yourself in your boss's shoes.  He wants you to come up with a workable system ASAP using off the shelf equipment.  Whether the AirX is the answer, I don't know, but I've seen small units set up in remote places that might do the job.  Check some of the units designed for use on boats.  Good luck.

[ghurd]

I would say have a look at one of the 'Solar Load Calculator' work sheets online.

Less than an hour will tell almost everything you need to know about what you'll need.

The worst case numbers give you a lot higher cost in just PV panels than your budget.  But if the installation is very remote, it could be less costly than just running the grid in.

G-

[BT Humble]

I had already thought about mounting the panel(s) and the batteries up the tower a good ways to keep cattle and varmits from destroying them

Solar powered lighting has really taken off here in the last few years - you see quite a lot of them in highway rest areas and such, where there's a fluoro street lamp with a ~40W panel mounted above it on the 30' pole (to make it hard to get an accurate hit with a rock I suppose?)

BTH

[BullCreek]

Thanks for all the comments.  I tested a different mainboard today that only draws 30W all loaded up, so I think I'm going to try solar only at first with 3 slightly used 80W panels and 420 amp hours worth of batteries and test it for a month or two to see what happens.  If the solar only doesn't cut it, I guess I'll continue researching wind between now and then and maybe try to build on of Hugh's 4ft turbines for fun.  FWIW, I was skimming the latest issue of Home Power last night and came across a new meter that might work well for monitoring the batteries over the network:

http://bogartengineering.com/pentametric.htm

Thanks again,  --J