Wind & Solar Charge Controler one battery bank

KNLsolar

I currently have an off grid 300 watt PV system with a battery bank. Is it possible to hook up a wind charge controler to the same bank at the same time? Trying to avoid buying an all in one Solar & Wind charge controller. Thx!!!

Estragon

Yes, you can run multiple charging sources to a single bank.

The wind controller needs a dump load (eg water heating) to load the turbine when the bank is full or some other way to avoid overspeed.

KNLsolar

I plan on having a 300w wind generator minted above my air conditioner compressor outside. Seeing as that's the case would I still need a dump load since the wind speed would be the same?

bill von novak

KNLsolar said:

I plan on having a 300w wind generator minted above my air conditioner compressor outside. Seeing as that's the case would I still need a dump load since the wind speed would be the same?

That's a worrisome statement.  That suggests two mistakes:

1) Mounting a wind turbine on a habitable structure.  The noise will drive you nuts.
2) Mounting a wind turbine on a short tower on a roof.  This will generally result in poor performance.

To answer your original question, you will need a dump load if your turbine has a direct connection to your battery bank.  The dump load will prevent overcharging.  If you have a separate regulator/brake you will not need a dump load, as the regulator will deal with that for you.

KNLsolar

Thanks for the reply. Here is my plan as far as the set up for wind... https://m.youtube.com/watch?v=pwE3UlSmTh8

Not my video but what I plan on doing. Already had a generator hooked up and make some noise but is drown out by the sound of the ac unit.

So If I get a wind charge controler I can hook it up to my battery bank at the same time my PV system is charging?

bill von novak

KNLsolar said:

Thanks for the reply. Here is my plan as far as the set up for wind...

Uh - you have a wind generator that's being spun by your A/C fan?  Just want to make sure I have that right.

mcgivor

Interesting concept in theroy, using the air to generate power to recover some  the otherwise lost energy. Have seen the condenser used to heat domestic water, that air is hot so may have a detrimental affect on the wind turbine.

mcgivor

A dump load is generally used to prevent the turbine from over revving the turbine  in no load conditions, a load acts as a brake so to speak, when the battery is fully charged, a diversion controller would be used to divert the turbine output to a dump load to avoid such problems. In the case of a fan providing the "wind" perhaps a dump load is unnecessary??
In an off grid situation where the air conditioning unit is being powered by the same battery being charged by the turbine , the A/C load would exceed the turbine input and only feeding back on an on cycle, in this case a dump load would definitely not be required.

BB.

In general, there is no such thing as a free energy. Unless it is well designed (and verified by testing), I would assume the video system would:

• increase back pressure on condenser circulation fan--Less air flow, less cooling available, higher compressor pressures, higher energy usage
• instead of hot air being directed straight up and away from condenser--Your hot exhaust air is now "floating" just have the A/C unit and possibly being pulled back into the condenser--Higher condenser inlet temperatures, higher compressor pressure, higher energy usage

There are cases where waste heat can be used effectively such as the P51 WWII fighter:

https://en.wikipedia.org/wiki/Meredith_effect

If you can, there are other ways to recover energy from an A/C system... One is to install a de-superheater in the compressor output line. Basically circulate water through a heat exchanger to pull the heat from the A/C compressor output. You get "free hot water" (domestic hot water, swimming pool heating) and reduce the back pressure on the A/C pump do to lower condenser temperatures.

https://www.doucetteindustries.com/ (I know nothing about site or produces listed--Just a starting point for your research)

And another option is to convert your water heater (especially electric water heaters) to a heat pump type. In warm to hot climates, a heat pump water heater will use 1/3rd the energy of a typical resistance electric water heater (and can be even less than a gas/propane water heater operating costs). Plus you get "free" cold/dehumidified air out of the water heater (I am not recommending these links--Just for your research).

http://www.geappliances.com/ge/heat-pump-hot-water-heater.htm
http://www.hotwater.com/water-heaters/residential/electric/proline/xe/voltex-hybrid-electric-heat-pump/
https://www.amazon.com/Geyser-R-Heat-Pump-Water-Heater/product-reviews/B00A7UONEW

One (now retired) member suggests that heat pump hot water is easier/cheaper in the long term vs solar thermal hot water (lots of pumps, valves, plumbing to keep working):

Older posts:

If you want a do-it-yourself kit... This one appears to be hard to beat:

www.solarroofs.com

Solar Guppy has many years experience with a system from them and has been pretty happy. It does require proper maintenance to keep running well and to prevent problems (like freeze damage).

There have been a few threads here that link back to several extensive home projects--right down to installation photos, and documentation of mistakes and corrections...

Link 1
Link 2
Link 3
www.arttec.net/Solar/BarnHeat.html (also sells battery based Differential temperature pump controller).

Follow the off-forum links. The several projects/websites highlighted are very educational.

And this one is a bit more low tech home made heating system. Also very interesting and informative.

Between the two above links, they probably give the best detailed explanations of how to do a major home heating/domestic hot water project that I have seen.

The second one is, by itself, probably not practical for a city home system--but both give great ideas of the scope of such projects.

-Bill

If you are interested in sustainability... I have spent many hours reading Guy Marsden's website in years pasts. He also shows his mistakes made over time (you can learn more from mistakes):

http://www.arttec.net/

-Bill

Lumisol

I don't see the two bulleted points being valid concerns. Air does not float when forced through a fan and heated, just the heat will cause it to rise even after leaving the thrust zone.
Back pressure would only increase if the top fan were forcing air downward against the flow of the lower fan, but since it is just riding the currents, it won't cause any more back pressure than a telltail streamer would.

BB.

You have to get air motion through the driven blades... There has to be a pressure difference across the driven fan blades. If the driven blades are "far away" from the exhaust fan--Then perhaps there will not be any "back pressure" to the condenser (I would think that these are close coupled fans, not far apart).

In any case--It would be interesting to do some tests... Measure compressor output pressure and/or temperature. Measure compressor and exhaust fan energy usage. See if you can measure any differences between running the system with the energy recovery devices or not.

If your exhaust fan is (for example) 200 Watts--How much energy is recovered? Say 30% efficient fan and recovery device:

• 0.30 * 0.30 = 0.09 recovery
• 200 watts * 0.09 = 18 watts (guesstimate)

Now--It is possible to recover energy from the exhausted heat in the condenser and get additional energy recovery from the expansion of the heated waste air... But, in general, to get any "decent" return in energy, you need 1) higher working temperature levels--like a turboprop engine and 2) you may need the "exhaust fan" to be "in front" of the condenser (air=>fan=>condenser=>driven fan).

If you can recover 10% of the exhaust fan motor energy (and not increase energy usage elsewhere in the system)--Then you are probably doing really well.

Otherwise, I would suggest that recovering waste heat for water heating may be a better long term investment.

Here is a company that makes a similar system for large cooling towers/ventilators. And they have some numbers (I know nothing about site or company--Just some "verified" numbers):

http://www.tamenergy.com/testing-sertification.php



This is about 10x the size of a standard home A/C system condenser fan (I guess).

So, if my numbers are anywhere near accurate (9% of 200 Watts):

• 18 watts * 24 hours per day * 1/1,000 watts per kW = 0.432 kWH per day
• 0.432 kWH * $0.15 per kWH (typical) = $0.0648 per day
• 3 month cooling season * 30 days per month * $0.0648 per day = $5.83 per heating system.
• $599 per A/C condenser
• ~100 year cost recovery (3 month 100% duty cycle per cooling system)????

-Bill

mcgivor

To say there would be no back pressure without testing would merely be a guess, there is a lot more going on in airflow which is invisible, turbulence, vortices and so forth, introducing an obstruction will most likely cause some changes in the air flow of the exhaust fan, which were not factored for in the design process. Being so close may even create shock waves between the two causing slip and reduced efficiency of one, or both.

By no means do I claim to have the answers, but without using smoke, high speed cameras and viewing in slow motion, measuring load current etc etc, one can only speculate.

Lumisol

I have been in HVAC for years and this idea is basically silly, A standard home condenser fan motor will blow the air well over 30 feet into the air without anything in it's path. adding a turning blade that is moving the air in the same direction is a non issue. The main consideration is not the exhaust, but the air flow over the coils that is important. Keep the coils clean and free from obstructing vegetation and you are fine.
At my house in the valley we run the A/C from April through late October and early November. That a bit more than 3 months by my calculations. Just saying.
Assuming that a turbine will cause back pressure on the winds turning it is to assume enough turbines in an area could stop all winds from blowing. It works with the differences in pressure from one side of the blade to the other. It doesn't stop wind.

jonr

Wind turbines (and all other obstructions, upstream or downstream) do slow down wind/air flow.  Even if you don't have instruments sensitive enough to measure it.  It's significant at distances less than one rotor diameter away.

Waste heat recovery from AC is proven to be effective.  

BB.

I am a big believer in the laws of thermodynamics:

https://en.wikipedia.org/wiki/Ginsberg's_theorem

1. You can't win. (consequence of first law of thermodynamics)
2. You can't break even. (consequence of second law of thermodynamics)
3. You can't even get out of the game. (consequence of third law of thermodynamics)

In the end, it is possible (and can be very practicable) to increase efficiencies and recover "waste heat" for other uses (domestic hot water, swimming pool heating, etc.).

Does anyone have actual measured output power harvested from the A/C recovery fan in the video? The commercial sized system that I found would indicate that for listed price and available harvest--It is simply not cost effective (excluding maintenance over 100 year life in weather, replacing the GT inverter every 10 years, possibly loss of A/C efficiency, etc.).

-Bill

bill von novak

A standard home condenser fan motor will blow the air well over 30 feet into the air without anything in it's path. adding a turning blade that is moving the air in the same direction is a non issue. The main consideration is not the exhaust, but the air flow over the coils that is important. Keep the coils clean and free from obstructing vegetation and you are fine.

Agreed.  And why do you have to clear obstructing vegetation from the inlets?  Because that restricts the flow of air into the unit.  Restricting either the intake or exhaust will reduce airspeed over the coils and reduce the efficiency of the condenser.

Assuming that a turbine will cause back pressure on the winds turning it is to assume enough turbines in an area could stop all winds from blowing. It works with the differences in pressure from one side of the blade to the other. It doesn't stop wind.

It does reduce windspeed right in front of (and behind) the rotor, though.  And that's the effect that we are talking about here.  The energy to spin the turbine has to come from somewhere, and in this case it is coming from the fan's motor.  That can have one of two effects:

1) Slowing down the fan (and thus decreasing airspeed)
2) Requiring the fan to use more energy to spin at the same speed (thus increasing power drawn)

There is no such thing as a free lunch, to summarize the laws of thermodynamics.

Lumisol

This will not cause any such restrictions of the air flow that will impede the cooling, by the time the air is a foot out of the box, it has removed all the heat it will remove, it does not continue to remove heat from the condenser after that.

This isn't a free lunch, it is capturing and using wasted energy.

BB.

Any numbers yet on how much power/energy such a system will harvest from a real a/c condenser system?

Here is a bit of information on designing a cooling tower and how reducing exhaust air velocity increases the percentage of recirculated air when there is windy weather:

Cooling Tower Fundamentals - SPX Cooling Technologies (starting ~page 24 of file)

It does look like we are talking about recirculation in the region of 1%-5% (commercial cooling tower design)... With lower velocity exit air increasing the recirculation percentage.

And if you are looking at 9% of exhaust fan recovery (200 watt fan, 18 Watt recovered) vs a 1,500 Watt A/C system--That is about:

• 18 watts / 1,500 Watt A/C system power = 0.012 = 1.2% energy recovery.
  

How much more system power does it cost if there is 1% to 5% recirculation of exhaust air? At best, nearly a wash (decreased system efficiency vs recovered waste air energy--before capital+maintenance costs)?

-Bill

Lumisol

Cooling towers are almost never put up against a residential home as far as I know. There won't be any re circulation of air in the proposed system.
Anything the turbine produces will be from what would have been wasted energy.
Sure, you could say the turbine is likely to attract a large flock of birds to the coils that will then cause the condenser to trip the overheat sensor and shut off the A/C but that isn't going to happen either. lol

Recovering any of your wasted energy is a good thing no matter how much or how little. Hundred dollar bills are made from pennies.

Lumisol

It looks interesting, let us know how it goes for you, @KNLsolar.

Marc Kurth

This is not a new idea and there is a reason it isn't successfully being done commercially. System manufacturers are always looking for ways to claim higher efficiency and sell more equipment.

This is a parasitic device, not an energy recovery device.

Every rookie technician knows that the splash effect of the airflow hitting something close to the fan, will cause some re circulation back to the condensing unit intake in most installations. The amount will depend upon details of the design, but the more power produced, the more the negative impact on the AC system. The guy in the video even talks about the final version having a shroud........

It boils down to this:
In order to get any meaningful power output, you will negatively impact the AC system efficiency.

Note that the video doesn't talk about wattage being produced. Can this approach produce some power? Yes, of course - but how much? I would suggest that there are hundreds of others things that would save far more energy, with far less money. 

There is no doubt that the net cost of this arrangement will prove to be the most expensive power that the user ever purchased or produced. Fun experiment for a tinkerer? Sure, why not!

Marc

Lumisol

The shroud is to keep fingers from getting into the blades.

Note that the video doesn't talk about wattage being produced. Can this approach produce some power? Yes, of course - but how much? I would suggest that there are hundreds of others things that would save far more energy, with far less money.  

Yes, and after all those things have been done, there is this to do even more.

bill von novak

Lumisol said:

This will not cause any such restrictions of the air flow that will impede the cooling,

If it does not cause any resistance to the airflow at all, then it cannot capture any energy from that airflow.  That's simple flow dynamics - and that's why removing plants from near an A/C unit will improve efficiency, just as putting a fan (or lots of plants, or a board) above it will reduce efficiency.

by the time the air is a foot out of the box, it has removed all the heat it will remove, it does not continue to remove heat from the condenser after that.

Correct, and no one is claiming that it does.  What they ARE claiming is that increasing the backpressure will either reduce the efficiency of the condenser (by slowing the airflow) or require more power to drive the fan motor (so it can maintain the same airflow against more resistance.)  Again, basic thermo.

Lumisol

You are assuming that kite effect is the only thing that makes a turbine turn, there is also Bernoulli's principle.

The idea is one that will work and not damage any A/C components in any way. Again, basic common sense.

Bernoulli's principle does not cause any back pressure. 

bill von novak

Lumisol said:

You are assuming that kite effect is the only thing that makes a turbine turn, there is also Bernoulli's principle.
The idea is one that will work and not damage any A/C components in any way. Again, basic common sense.
Bernoulli's principle does not cause any back pressure. 

Lift does indeed cause backpressure.  Ask any pilot what ground effect is, or why a windmilling prop is bad during an engine out.

You are correct, that will not damage any A/C components.  It will merely cause the system to run less efficiently.

Lumisol

Ever have to autorotate a helicopter? No?
You seem confused about the original post.
You keep mentioning unrelated hyperbole.
The A/C is built with a very large margin of efficiency and it will not loose enough to even be worth mentioning. Like putting a hand out the car widow at 55 mph will reduce efficiency of the car. Adding a free standing antenna to the car will also reduce it's efficiency, but will it ever matter? no.

BB.

Streamlining does help even at 65 mph. My old plane had shaped tubing. And most vhf aircraft antenna are at 45 degrees for less drag.

And a rotating dead engine kills the glide ratio. If the engine dies, slowing the plane down to stop the prop or feathering the prop helps a lot. Drag of a stopped prop is much less than a spinning prop driving a dead engine.

But regardless of the above, how much energy or power is harvested by the device on the condenser?

I estimated roughly 1% energy recovery. 18 watts recovered out of 1,500 way a.c. system.

If I am close, then a 1% to 5% reduction in system efficiency due to recirculation (reduced exhaust air speed) is not insignificant.

If the recovery device can recover 200 watts, then recirculation loses are less of an issue.

- Bill

Marc Kurth

I keep coming back to the cost analysis. How many watts are produced compared to invested cost? We can all build a lot of things that cost a lot more than they are worth. How is the the guy in the video doing with his business? Hmmmm, the domain name is for sale now. Real life facts have a habit of getting in the way of dreams.

Oh, wait...... I just realized that this just might become Elon's newest pet! He can offer them for $299.99 each, to the first 500,000 people to get in on the ground floor.

Marc

Lumisol

BB. said:

Streamlining does help even at 65 mph. My old plane had shaped tubing. And most vhf aircraft antenna are at 45 degrees for less drag.

And a rotating dead engine kills the glide ratio. If the engine dies, slowing the plane down to stop the prop or feathering the prop helps a lot. Drag of a stopped prop is much less than a spinning prop driving a dead engine.

But regardless of the above, how much energy or power is harvested by the device on the condenser?

I estimated roughly 1% energy recovery. 18 watts recovered out of 1,500 way a.c. system.

If I am close, then a 1% to 5% reduction in system efficiency due to recirculation (reduced exhaust air speed) is not insignificant.

If the recovery device can recover 200 watts, then recirculation loses are less of an issue.

- Bill

I wouldn't assume you estimates are even close to accurate as they are based on unrelated things and not on any real in use system analysis. Anyone can pull numbers out of thin air to make any point they like.

It's a good idea to recycle and reuse spent energy any way you can. That's what it's all about.

BB.

My estimates where based on laboratory tests for the condenser fan efficiency. And the driven fan was based on a the free air efficiency of a near ideal wind turbine.

And the second linked site was based on a10x larger cooling tower physical test results with a ducted driven fan (which should be more efficient than a free air turbine).

In any case, what is the harvested power of this unit that is claimed / measured for the unit on YouTube (I even linked to the sales page)?

I did not find any power numbers listed on either location...

I am not claiming that my numbers are real... But lacking any other information, they are a starting point.

It is highly unlikely that the unit would recover 100% of the exhaust fan input electrical power [i.e. 200 watts in, 200 watts out]. And 100% efficiency would barely break even on the recovery system costs (original system cost - recovered electricity credit).

- Bill

Lumisol

It's a good idea to recycle and reuse spent energy any way you can. That's what it's all about.