PV and Wind coupling

Greetings,

Finally our dream of a remote cabin has come true after MANY years of hard work and looking...
Anyway, I will be setting up a PV and wind system and have the following questions that would need clarification and to that extent I look at the experts out there that have done what I plan; so here goes...

1) I will be setting up a 1Kw PV system and want to also install a 1.5Kw wind generator all rigged to Deep Cycle Batteries ..fuses...disconnect switches etc
2) I have a MPPT PV charge controller and a 3.0 Kw PSW Inverter.
3) If would like to link the wind generator to this set-up from its rectifier rather than from a dedicated hybrid generator/solar charge controller...can this be done?

Someone said that i could link the output from the wind rectifier to the PV charge controller input in parallel with the PV panels.. would this work without confusing the PV controller or even blowing it up?

Thanks
Eric :confused:

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: PV and Wind coupling
    Retired747 wrote: »
    Greetings,

    Finally our dream of a remote cabin has come true after MANY years of hard work and looking...
    Anyway, I will be setting up a PV and wind system and have the following questions that would need clarification and to that extent I look at the experts out there that have done what I plan; so here goes...

    1) I will be setting up a 1Kw PV system and want to also install a 1.5Kw wind generator all rigged to Deep Cycle Batteries ..fuses...disconnect switches etc
    2) I have a MPPT PV charge controller and a 3.0 Kw PSW Inverter.
    3) If would like to link the wind generator to this set-up from its rectifier rather than from a dedicated hybrid generator/solar charge controller...can this be done?

    Someone said that i could link the output from the wind rectifier to the PV charge controller input in parallel with the PV panels.. would this work without confusing the PV controller or even blowing it up?

    Thanks
    Eric :confused:

    Okay, first things first.
    You need a number for how much electric you'll use. All off-grid systems are based on daily Watt hours. When you try to do it some other way you end up disappointed and broke. With that and the maximum Watts at any given time you can determine the proper size for your battery bank.

    The solar array is sized to recharge that battery bank. The wind turbine is sized according to how much money you can afford to throw away on something that probably wont do any good anyway. That's only slightly a joke: small wind turbines are notoriously over-rated for their performance.

    You do not connect the turbine output and the PV output to the input of the same charge controller; the two power sources are in no way compatible. There are three levels of combined system:

    1). Small, with the PV and turbine connected directly to the batteries. Charging from both is regulated by a dump controller connected to the batteries.

    2). Medium, with the PV on one charge controller the turbine connected to the batteries and a dump controller connected to the batteries.

    3). Large, with separate MPPT type controller for PV and turbine. The turbine's controller will also have a dump load arrangement (look up MidNite Classic & Clipper).

    So let's go back to the basics and find out how much power you'll need to supply.
  • Retired747Retired747 Registered Users Posts: 10
    Re: PV and Wind coupling

    Thanks Cariboocoot..points taken..I had a feeling that the advice I was given re. parallel connection of wind and solar on the same controller was a load of c...p
    At the moment I do not know what exactly we will be running at the cabin, as we plan to run as much as possible on propane, so I was just trying to plan ahead with something to start the off-grid setup. I may just start with the 1Kw PV set up, MPPT, inverter, batts as this can always be expanded at a later stage. My philosophy is to 'over-size' rather than... 'I wish I had'
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: PV and Wind coupling

    What are the specs on the inverter and charge controller you've got? They may be limiting factors. Hopefully it is not a 12 Volt inverter, for example.
  • jcheiljcheil Solar Expert Posts: 722 ✭✭✭
    Re: PV and Wind coupling
    Retired747 wrote: »
    Thanks Cariboocoot..points taken..I had a feeling that the advice I was given re. parallel connection of wind and solar on the same controller was a load of c...p
    At the moment I do not know what exactly we will be running at the cabin, as we plan to run as much as possible on propane, so I was just trying to plan ahead with something to start the off-grid setup. I may just start with the 1Kw PV set up, MPPT, inverter, batts as this can always be expanded at a later stage. My philosophy is to 'over-size' rather than... 'I wish I had'

    It is very difficult to "expand" solar once you have the base system in. Especially if you paint yourself into the 12v or 24v corner when you ultimately might end up needing to be at a 48v system. As mentioned, try to determine your loads right now and what you expect them to be in the future so that you don't end up buying stuff that you will ultimately have to throw away. Many here have done that, myself included.
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • Retired747Retired747 Registered Users Posts: 10
    Re: PV and Wind coupling

    Thank you both for your observations all of which make great sense.

    At the moment I am at the planning stage and this would be it:
    1) 24VDC 60A MPPT Charge controller
    2) 24VDC 3Kw PSW Inverter/Charger (Auto C/O or Manual no big deal) may also have another 1Kw PSW for when heavy loads are no in use.
    3) Starting with 1Kw PV's then adding some more when needed
    Also thinking of adding (maybe sooner than later) a 1 - 1.5Kw wind generator with its own controller or might opt from the get-go for a Hybrid PV/Wind/Charge controller with a view to adding the Wind generator unit when I have replenished the finances!!

    What are your thoughts?

    Thanks
    E
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: PV and Wind coupling

    Well let's look at it 'sideways':

    1kW of PV on a 24 Volt system would have a peak current of about 32 Amps using an MPPT controller. That would be what is typically recommended for around 320 Amp hours of battery. If you use an average 25% daily capacity of that you get about 1.9kW hours of electricity before inverter consumption and conversion loss. A respectable amount of power.
    may also have another 1Kw PSW for when heavy loads are no in use.

    Possibly a redundant caution here but ... you can't stack any two inverters, and the total power for both coming from one battery bank is a limiting factor. For example 3kW on 24 Volts is about 125 Amps, or 39% of the Amp hour capacity of the above battery. That is a hefty draw. Add another 1kW to that and you hit 167+ Amps which will 'flatten' a 320 Amp hour battery bank instantly (i.e. severe Voltage drop due to load). Something to be avoided. Most of the time you probably will not use 3kW; you'd be amazed how much power that is. For me it's 'turn everything on at once' including the microwave and septic pump. This doesn't happen.

    Before you put even $1 into wind power understand the three big failings of it:
    1). Site does not have enough sustained wind at a sufficient velocity to make turbine viable.
    2). Turbine is an over-rated piece of junk that never supplies claimed power in good wind and/or falls apart.
    3). Installation is not done properly; blades not high up in non-turbulent air to be practical.

    Good wind turbine power costs quite a bit more per Watt than solar, and requires maintenance.
  • Retired747Retired747 Registered Users Posts: 10
    Re: PV and Wind coupling

    Great advice... I am learning allot today!! :D

    The 2 inverters scenario would never be used at the same time...I would turn on & use whichever was needed at the time..I know this is hassle but it would avoid unnecessary drain on the batteries, as you have explained. Having a 3Kw unit delivering a few watts when a 1Kw could cope perfectly without drawing as much as the 3Kw.

    The cabin location is on high ground (4500Ft - 1400Mt) and I have noticed a respectable wind that is quite constant...having said that, I would probably wait 'till we move up there to ascertain if the expense would be justified for a w/Generator. I thought a wind generator could probably make up for cloudy/rainy days and of course night time generation, what do you think? Or should I invest the $1000 or so for additional PV's rather than a wind generator?
    I also have a 6500W Gas generator as a sby

    I anticipate we will have a family size refrigerator + freezer + washer & dryer the rest would be propane (ie stove, hot water) lighting will be 120V LED's, heating is wood stoves.

    Thanks
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: PV and Wind coupling
    Retired747 wrote: »
    Great advice... I am learning allot today!! :D

    The 2 inverters scenario would never be used at the same time...I would turn on & use whichever was needed at the time..I know this is hassle but it would avoid unnecessary drain on the batteries, as you have explained. Having a 3Kw unit delivering a few watts when a 1Kw could cope perfectly without drawing as much as the 3Kw.

    Sensible strategy to a point. But check what the inverters' consumption numbers are: a 1kW unit can use as much for itself as a 3kW unit.
    The cabin location is on high ground (4500Ft - 1400Mt) and I have noticed a respectable wind that is quite constant...having said that, I would probably wait 'till we move up there to ascertain if the expense would be justified for a w/Generator. I thought a wind generator could probably make up for cloudy/rainy days and of course night time generation, what do you think? Or should I invest the $1000 or so for additional PV's rather than a wind generator?

    In most cases the extra PV will be a more sure-fire return. Good wind for turbines is in the steady 20 mph range, and such an environment is unpleasant to live in. What we think is good wind turbines scoff at.
    I also have a 6500W Gas generator as a sby

    Best idea yet. Or invest the turbine money in a small inverter-generator like a Honda EU2000i. You may notice how many of us on here have them as back-up power. Works in any weather so long as there's gasoline. They are also quiet and economical - especially for the varying loads normally associated with recharging batteries.
    I anticipate we will have a family size refrigerator + freezer + washer & dryer the rest would be propane (ie stove, hot water) lighting will be 120V LED's, heating is wood stoves.

    Okay I run a standard refrigerator (16 cubic foot). It uses about 1.2 kW hours per day. Some of the newer ones are even better. Not a problem. Freezer may double that power consumption depending on size/efficiency. Washers tend to be power hogs (there's a thread about best off-grid washing machines on here: http://forum.solar-electric.com/showthread.php?23150-I-have-found-the-ultimate-off-grid-Washer-I-use-it-and-I-love-it). Dryer had better be gas, even then they have some power-hungry igniters. Forget all-electric ones: they have very high Watt heating elements (think about it: 30 Amp 240 Volt outlet to run one). We actually wash by hand and dry on a line.

    If you see my sig you see how minimal my system is. I have some advantages with long daylight hours (not there in Winter - it would be totally impractical) and high elevation. Your 4500 feet will probably get you about 7% better output than would normally be expected. :D
    Even so I would like to expand my system at least in panels. Most of the power is used during the day when they are producing and the batteries simply carry through 'til the next charge cycle. This is very efficient but requires active load management. If the kids are there on their own ... oh boy. Dead batteries at 2:00 AM because someone used the water pump after dark without running the generator!
  • Retired747Retired747 Registered Users Posts: 10
    Re: PV and Wind coupling

    Thanks again ...it all makes sense..as you say it might be more sensible to put the extra cash into more PV's maybe 1.5Kw? What do you think? and in your opinion what is a good battery bank to have for a 1.5Kw panel setup?

    BTW I was looking into some other charge controllers and have sourced a 60A MPPT capable of handling up to 150VDC, so with a 2KW array I could run at say 96VDC and be able to use smaller cables from the panels and the controller should be able to handle it? :D
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: PV and Wind coupling
    Retired747 wrote: »
    BTW I was looking into some other charge controllers and have sourced a 60A MPPT capable of handling up to 150VDC, so with a 2KW array I could run at say 96VDC and be able to use smaller cables from the panels and the controller should be able to handle it? :D

    The current limit on the controller is at the output, not the input. So it's the battery bank voltage which is the limiting factor: 24V x 60A = 1440W. This is why if you're considering a larger system it's better to go with 48V battery from the start.
    Regarding wind or more solar, you don't have to make that decision now because it's easy to add either of those after the initial install when you're living up there and are more familiar with the local weather.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: PV and Wind coupling
    Retired747 wrote: »
    Thanks again ...it all makes sense..as you say it might be more sensible to put the extra cash into more PV's maybe 1.5Kw? What do you think? and in your opinion what is a good battery bank to have for a 1.5Kw panel setup?

    BTW I was looking into some other charge controllers and have sourced a 60A MPPT capable of handling up to 150VDC, so with a 2KW array I could run at say 96VDC and be able to use smaller cables from the panels and the controller should be able to handle it? :D

    In addition to what Stephen has said, you would not want to run the controller at 96 Volts for a 24 Volt system as it reduces the controller efficiency. It is best to stay at no more than 2X nominal system Voltage for the nominal array Voltage. That is 48 Volts for a 24 Volt system. Usually that gets the Voltage up to where V-drop is not a big concern. If the distance is really long you have to decide where you want to lose the power: in the wiring or in the controller.
  • Retired747Retired747 Registered Users Posts: 10
    Re: PV and Wind coupling

    Point taken from both you gentlemen...

    I think the 48V is the way to go especially as many inverters are able to cope whereas a 96V would be a different matter!

    So I think I will start with 1.5Kw PV with the 160A MPPT...any suggestions for a reasonably priced PSW inverter to compliment this setup...say 2.5 - 3Kw?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: PV and Wind coupling
    Retired747 wrote: »
    Point taken from both you gentlemen...

    I think the 48V is the way to go especially as many inverters are able to cope whereas a 96V would be a different matter!

    Array Voltage on an MPPT controller is not that closely tied to system Voltage. The inverter will only see what the battery Voltage is, not the array Vmp.
    So I think I will start with 1.5Kw PV with the 160A MPPT...any suggestions for a reasonably priced PSW inverter to compliment this setup...say 2.5 - 3Kw?

    Well there's no such thing as a "160A MPPT" but other than that ...
    You're probably getting confused by the standard model designations in Amps (60 Amp MPPT) and MidNite's use of maximum input Voltage for model numbers (Classic 150, 200, and 250).

    Now, define "reasonably priced".
    Inexpensive with no built-in charger and limited functionality but serviceable?
    Or all-out inverter-charger that can do most anything you want?

    Low end: Samlex 3kW unit http://www.solar-electric.com/sa3wa24vosiw.html $1,189
    High end: Outback 3.5kW unit http://www.solar-electric.com/outback-power-pure-sinewave-inverter-vfx3524.html $1,770

    Frankly the Outback is significantly better than the Samlex in many ways. The Outback will need a MATE programmer so it's about $300 more than listed.

    You could also get a Magnum 4kW unit http://www.solar-electric.com/maenms4040wa.html for $2,079. Debatable value over the Outback, which has a better charger system.
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