Remote WISP Power

[devo]

Hi, great to see a company with an active forum! This one is a great resource for everyone. I had a couple questions that perhaps someone here could help with.

First a bit of background. We're a small wireless internet service provider in Canada working on a new long range microwave project. Our plans are for 5 new remote tower locations this spring to compliment our existing infrastructure.  We've built 4 off-grid tower sites so far and are expanding our network.

So far we've estimated our power requirements to be roughly 130Kw/h per month, per site. We're planning to utilize both wind and solar for energy generation as we currently do at our existing sites. From previous experience we believe approx. 1Kw of solar and 2Kw of wind with 400 - 500 Ah of batteries at 48VDC should be adequate.

We plan to use a Classic 250 w/ a Clipper for the turbine and a Classic 250 for the solar.

We are using 8 foot x 8 foot x 8.5 foot standard shipping containers for our equipment shelters. The containers will be well insulated.

How much heat will a Clipper generate in normal operation? Will the heat be dissipated into the building, or is it mostly contained in the clipper enclosure? Our current setup has been to use a MorningStar TS-45 in diversion mode dumping to a resistor. In our existing smaller buildings this has worked well, and generates enough heat to keep things from freezing in the winter months.

Does the clipper shut down the turbine when the batteries are full? If so, is there any way to allow the turbine to produce energy and dump to a resistive heating load?

If anyone could provide some insight it would be greatly appreciated!

[Westbranch]

here is a link for a new turbine that has some interesting discussion.

http://www.wind-sun.com/ForumVB/showthread.php?18366-New-Off-Grid-Wind-Turbine

Why are you planning on a CL 250  when a 150 should handle the load @ 48V?

[dgd]

First a bit of background. We're a small wireless internet service provider in Canada working on a new long range microwave project...
we've estimated our power requirements to be roughly 130Kw/h per month, per site.
1Kw of solar and 2Kw of wind with 400 - 500 Ah of batteries at 48VDC should be adequate.

..similar setup to a wireless internet  repeater we seutp last year (in New Zealand)
8 L16s, 1.2Kw PV, 500w wind turbine, C150, Cisco 3845 switch/router, 5.56Ghz .5w 11gbit radio cards,  26db frame dishes..etc
With an HP pc subfeeds to 3 2.26Ghz 8db flat plate 120deg antennae the monthly power take was close to 125Kw/hr
It was a bit tight power in vs power out, the service tech had to visit each month with a 6kvA genny and EQ the L16s

Our current setup has been to use a MorningStar TS-45 in diversion mode dumping to a resistor. In our existing smaller buildings this has worked well, and generates enough heat to keep things from freezing in the winter months.

The prevoius setup we had was a Xantrex C40 pwn controller in diversion mode
The move to the Classic 150 mppt controller was the best upgrade we did, About 20% more solar power. We direct connected a low cost Missouri W&S dual alternator wind turbine to the batteries and let the Classic aux output switch into the turbines 3 phase AC outputs some WW resistors. That slowed the turbine on the very few occasions there was wind when the batteries were full.

dgd

[dbcollen]

monthly power take was close to 125Kw/hr
dgd

You do understand that "/" means "per" so you are saying that you use 125kw per hour, that must be one hell of an array and battery bank. PLEASE USE THE CORRECT TERMS, if you use 125 kilowatt hours per month, than say you use 125kwh/mo. It is not that difficult

[dgd]

Doh!  guilty as charged   

[devo]

..similar setup to a wireless internet  repeater we seutp last year (in New Zealand)
8 L16s, 1.2Kw PV, 500w wind turbine, C150, Cisco 3845 switch/router, 5.56Ghz .5w 11gbit radio cards,  26db frame dishes..etc
With an HP pc subfeeds to 3 2.26Ghz 8db flat plate 120deg antennae the monthly power take was close to 125Kw/hr
It was a bit tight power in vs power out, the service tech had to visit each month with a 6kvA genny and EQ the L16s

It's great to hear about other off-grid setups! It took a few tries for us to get a system that works, but I'm still not entirely satisfied, hence using the Midnite controllers this time around.

The only hiccups I can see at the moment are the heating issues, as well as finding a suitable backup generator. We don't need a large genset, since it will only be used to charge batteries, but most of the nice standby units are 8 - 10Kw.

Perhaps the Clipper produces more heat than I realize. Our existing setup produces a substantial amount and uses similar resistors. With the fan's on the clipper, it may very well do the trick.

The only concern I have is that with the amount of power generation the batteries shouldn't be discharging much at all. I hope we can still use the turbine to generate heat, instead of the Clipper simply shutting it down.

[Westbranch]

What temperatures are we talking here that you need extra heat?

Here are a couple of  ongoing threads about backup gen sets

http://www.wind-sun.com/ForumVB/showthread.php?18459-Demonstration-of-Generator-Support

http://www.wind-sun.com/ForumVB/showthread.php?17569-Choosing-a-good-generator

[devo]

Generally I would prefer if our buildings/containers could maintain temperatures above 5C. To do that would likely require some sort of supplemental heat though.

On the low end, I wouldn't want the temperature to get below 0C.

Our existing sites are generally around the zero mark in winter, although during a cold snap they do dip down to -10C. It's really not a problem for the equipment, but low temps aren't good for the batteries.

Outside temps here range from +5C to -25C in the winter months.

[Westbranch]

Actually it is high temps that degrade FLA batteries...low temps are actually better for the batteries   however the output of the batteries is reduced until the batteries warm up.
For a fully charged battery to freeze it would have to be well below -40 (take your pick, C or F, both the same)
Also, charging does warm the battery as well.

From Trojan's site:

The only way that a battery can freeze is if it is left in a state of partial or complete discharged. As the state of charge in a battery decreases, the electrolyte becomes more like water and the freezing temperature increases. The freezing temperature of the electrolyte in a fully charged battery is -92.0oF. At a 40% state of charge, electrolyte will freeze if the temperature reaches approximately 16.0oF.

the batteries would have to be at -27 C to  lose 50% of their capacity

hth