classic on wind

[mahendra]

hi by how much can the classic boost energy harvest in wind mode?as compared to 10-30 % on solar.

[TomW]

hi by how much can the classic boost energy harvest in wind mode?as compared to 10-30 % on solar.

I do not have any hard data to cite. I can tell you that it really wakes up a turbine down in the low end. With the right wind track it lets the turbine spin up to higher RPM and higher volts which lets you grab power in the lower ranges.

This is perfect because energy harvest is not a sprint for the highest peak power but is a marathon trying to harvest more KWH over time. I see our turbine a lot of times giving 100 to 300 watts continuously in winds it would have done 500 watts for a short burst of power and then stall out until it did it again. If that makes sense?

Hope that helps. I think hard data would take wind tunnel testing of identical turbines in identical conditions. Probably varies by machine also.

Tom

Just what I see here.

[mahendra]

thanks

[boB]

Can't tell you exact energy harvest in percent of increase in kW-Hours  but we have seen
increases of peak power of around 250% over direct turbine to battery connections
in many cases.

boB

[mahendra]

thanks bob i am not looking for exact value i just want to have an idea of how much more power i can harvest and if its is  positive  to put a classic on the turbine in the long term.

[toothy]

I'm not real sure about this but I believe the turbine furling system design can have some effect on increased output. My Kestrel is rated at 1k and does 1K. I don't know the particulars about low wind increases.

Wade

[Halfcrazy]

That is absolutely true. If the turbine has active blade pith based on centrifugal force than the gain on the upper end will be less.

Ryan

[boB]

Chris Olson in Wisconsin (the wind blows there), builds wind turbines and has used the Classic quite a bit with wind.

I asked Chris if he could give me some ball-park figures and here is what he had to say......

It depends on system voltage.

On 12V I have determined it is roughly 3x

On 24v about 2x

On 48V about 30% increase.

Regards,
--
Chris & Kristin Olson

[ChrisOlson]

There are several factors that determine how much more energy you will get.  You cannot take a direct hooked design, fixed pitch 12V turbine, for instance, put a Classic 150 controller on it, and get 3x increase in energy output.  However, if you design a 140V turbine and use it on 12V you will get roughly 3x more kWh than the direct hooked one with the same size rotor.

The three things that make this possible is

• the increase in rotor efficiency (harvest more of the available kinetic energy from the wind by running the rotor at more ideal tip speed)
• massive increase in generator efficiency - it is almost impossible to build a generator of reasonable size and weight that puts out 60 amps @ 12V and is better than 50% efficient.  However, it is easy to build a generator that produces 140V and 5 amps and get better than 90% electrical efficiency, transmit that 5 amps to the controller, then do the step down conversion there.  Utility companies have been doing this for years with grid power
• less losses in the wire run and rectifier.

The advantages noted above are proportional to the system battery voltage.  So since 12V is inherently the most inefficient, it gains the most from using a power tracking controller.  48V systems gain the least by using a power tracking controller.
--
Chris

[mahendra]

 thanks guys that explains a lot although i don't fully understand.lol.

[kitestrings]

Tom, Chris,

Nicely explained.  Makes perfect sense.

The other opportunity that the Classic provides I believe is indirect, but noteworthy -

On a battery based system once the batteries are 'full', the charge is reduced.  If there is no place else for the power to go, then potential energy harvest is missed. And, some of the attempts to make things more efficient in the first place (efficient blades, matching, alternator efficiency) are for not.  With the Classic it is pretty easy to divert load to water heating, other discretionary devices so that more of the available energy can be harested.

I know Chris has done alot with water heating and may have more to add.

~ks

[ChrisOlson]

I know Chris has done alot with water heating and may have more to add.

My water heating system is undergoing constant upgrades.

Our latest system has one heating element that is for emergency use - it is powered all the time with a thermostat and it only comes on in the event we run out of hot water.  The system will typically start the generator if that element comes on when we have other loads on, because it puts a 4,500 watt load on the inverter.

To meet our daily hot water needs I'm driving one element with a AC SSR controlled by a XW-MPPT60-150 aux port.  We don't typically want to heat water unless we have power available to do it.  But we need to heat that daily consumption of hot water regardless, which takes anywhere from 4-7 kWh/day.  The MPPT60 takes care of that when adequate incoming power is available and a thermostat turns the heater off when it gets up to 150 degrees.  At that point we have 55 gallons at 150°F.  The heater element on the solar is a standard 4,500 watt 240V element on 120V power so it draws 1,050 watts.

As we have added solar installed capacity we no longer need the wind turbines for summer time.  So to use them in the summer I have two wind Classics each driving their own AC SSR with Waste Not Hi mode, and each has their own 2,000 watt 240V heating element in the 55 gallon water pre-heater.

The solar power and MPPT60's take care of battery charging, everyday normal loads and daily water heating.  If the wind turbines put any power at all the Waste Not "kicks in" and adds load to the inverter in direct proportion to how much power the turbines are producing - up to 4 kW of auxiliary load for wind.  This keeps the turbines from having to use the voltage clippers (I've burned too many of those to a black smoldering crisp), and uses their power for "opportunity" water heating.

If we get enough "opportunity" water heating done with wind power, it prevents the MPPT60's from having to heat water the next day.  So the solar power can be used to run other big loads instead, like our A/C unit for the house.

This has worked out far better than the original setup I had with one Classic driving a AC SSR and doing all the water heating with elements daisy-chained with thermostatic relays.  With the old system I only had 2 kW of aux load.  With the new system I have 5 kW of aux load.
--
Chris

[TomW]

This keeps the turbines from having to use the voltage clippers (I've burned too many of those to a black smoldering crisp), and uses their power for "opportunity" water heating.

So, how do you BBQ those Clippers? Just driving too much power in to undersized loads and is it the loads that fry or the circuitry / SSR? Are the turbines wound up too far to get braking at reasonable power shedding? Sorry for "20 question" but just curious what is happening. When my Clipper on the 12 footer kicks in I get immediate reduction in turbine RPM not the sudden nose to the windshield braking I get from a short but it is quick and positive loss of RPM.

I am way down the food chain on available wind power but am just curious how this happens and why?

Are you sure you are not using them as a dyno load while tweaking that pulling tractor? 

BTW, that wind track I got from you awhile back was a good start and I dialled it in a bit but the real answer to better matching and power would be higher voltage stator than the stock 24 volt one it has now. I get nice steady charge from it a lot better than direct in low winds.

Thanks.

Tom

[ChrisOlson]

So, how do you BBQ those Clippers?

By having the furling force set too high so the turbines put out 3.5 kW.  The battery and loads can only take so much when you have three turbines going at full bore - they literally stomp the solar right into the dirt for raw power output.  On the perfect day, with everything running flat out, we can see 17 kW of power input to the system from solar and wind.  It can't take that.  The controllers shut the solar down and if the wind is blowing 25 -30 we still got over 10 kW.  If the system goes into Float the clippers have to absorb it all.  It melts them into a black glowing pile of carbon.

So we have added more solar and I decommissioned one turbine.  Solar is easier to control.  When I take those turbines down before winter for servicing I'll turn 'em down a little bit so they don't go over about 2. 7 kW each.

My new setup lets the XW-MPPT60's handle charging, and this actually works better than the Classic because the MPPT60's have a feature called "Boost Charging", and the Bulk and Absorb voltages can be set separately to provide a finish stage.  Our batteries require IUIa charge profile, and the MPPT60's are the only ones on the market that can do that - and they shut off when the finish stage is done and don't float the batteries (you can disable Float in them).

I have the wind Classics absorb stage set 0.5V below the MPPT60's and this forces the Waste Not to activate as the MPPT60's push the voltage above what the Classic thinks is "right".  This adds up to 4 kW aux load to the inverter and keeps the turbines busy so the Classic doesn't unload them, and neither does it unload the solar input.  It forces the turbine power to go to water heating.

The clippers are now just used for turbine shutdown.  If the water heaters get hot and click out, then the Classics unload the turbine and let them free-spin up to 148V.  If the input voltage hits 148 the AUX1 snaps on, engages the clipper relay and shuts the turbine down for one hour:



After an hour expires it lets the turbine go again to "test" it and see if the power can be used now.  If it unloads the turbine again it shuts it down for another hour.  Eventually the turbine power can be used again and it leaves it running.

This has worked far better for me.  It doesn't bake clippers, doesn't run turbines when they're not needed, and is fully automatic shutdown in high thunderstorm winds where a 60 or 70 mph gust might drive the voltage too high.

BTW, that wind track I got from you awhile back was a good start and I dialled it in a bit but the real answer to better matching and power would be higher voltage stator than the stock 24 volt one it has now.

Yeah, putting a Classic on a stock turbine is sort of like taking a normally aspirated stock diesel engine and strapping a turbocharger on it.  You might get 10-12% power increase due to increased efficiency.  But put pistons in the engine with deeper fire cups to increase the combustion chamber volume and lower the compression ratio, put bigger injectors in it, and crank the fuel rate (design it for turbocharging) and you can easily get a 100% increase in power output at the same efficiency.

Since I've gone to 140V generators, the efficiency and power output has improved pretty dramatically over the lower voltage ones.  The downside with wind power is the distance you have to run power (usually) to get it to the utility room.  High voltage is the only way to go.
--
Chris

[Halfcrazy]

I should point out the Clippers Chris has smoked where not MidNite clippers. Although with the wind farm he has going he could probably test the ability of our clipper