Combined wind and solar MPPT charge controller ?

[dunedin]

From various other threads I see that it is worth getting a good MPPT charge controller for solar power - possibly something like the Victron Blue (though yet to size ampage requirement)
http://www.onboardenergydirect.co.u...controller-MPPT-100-15-VBS100_15.html#SID=271

But for some mad reason I am considering ultimately having a mix of solar and wind power - potentially a small wind device which is removable when not in use (this is the mad part of the idea, but definitely don't want a permanent installation)
I want to minimise the wiring complexity, so is having one controller with input options of wind and solar a viable option ? If so what products?

 

[VicS]

From various other threads I see that it is worth getting a good MPPT charge controller for solar power - possibly something like the Victron Blue (though yet to size ampage requirement)
http://www.onboardenergydirect.co.u...controller-MPPT-100-15-VBS100_15.html#SID=271

But for some mad reason I am considering ultimately having a mix of solar and wind power - potentially a small wind device which is removable when not in use (this is the mad part of the idea, but definitely don't want a permanent installation)
I want to minimise the wiring complexity, so is having one controller with input options of wind and solar a viable option ? If so what products?

The Marlec/Rutland wind turbines can be controlled by the Marlec solar regulators at the same time as solar panels.

eg the Marlec HRDi controller can be used with various Rutland wind turbines and up to 160 watts of solar panels in one system. It can also charge two separate battery banks simultaneously.

Other makes of wind turbines, eg LVM Aerogen, may need a shunt type regulator.

 

[William_H]

Probably quite feasable to run one MPPT controller with both solar and wind power. However the concept of MPPT is that the controller chooses the best fit of amps and volts to get the max power from the solar panel. It uses a a power converter to get the required volts for battery charging ie 14.2 volts (depending on stage of charging) from the voltage from the solar panel that gives most power.
To explain a 100w panel will produce 20volts at no or small current drain. (low power) It can be loaded up by sucking amps such that you get max current 5 amps but voltage drops so much that power is low or not optimum. Best fit for good sun is around 16volts at near max current. However this varies with the amount of sunshine. So in low sun shine it might decide that best power comes at a lower voltage and lower current.
As an aside... I did try a buck boost regulator on a small solar panel thinking that it would do the same job ie produce 14.2 volts from whatever the panel gave. The battery being low took lots of current at that voltage and the buck boost tried to provide it. What happens is that the boost regulator sucks more current when voltage falls to get the same output. But as the voltage falls because current rises the voltage of the panel falls even more so that the buck boost converter quickly dragged the panel down to low voltage high current so low/no power. So the MPPT controls the buck boost converter in it to rather than simply try to provide what the battery will take it accepts that it can't provide full power then makes the most of what it can do. Given best input from the panel.
Now if you decide to feed the DC from the wind gen in parallel with the solar panel. You will get a lower voltage at low wind speed and less current but this will likely over power or be overpowered by the solar. So you will get automatic changeover from solar to wind as a source but not often both at once.
So ideally an MPPT controller for both. Only then at full batteries will you get anything less than max power from each.
That is my theory. Perhaps you can get one controller for both but it seems to me the guts of the converter will have to be duplicated for both sources. Not likely. That is my theory anyway. olewill

PS a Buck boost regulator is a clever device switching DC into a transformer to give an output of the desired voltage 14.2
regardless of the input voltage ie between about 6v and 40v input. The output current to the load reflects in more current in if voltage is boosted or less in if voltage is bucked. So same power volts x amps less an inefficiency around 90%.
I use one actually just a buck regulator as a solar regulator from a fairly large panel, small battery such that it does not often drag panel voltage down
but this is not very efficient. But it stops over charging the battery. All very tricky.

 

[dunedin]

Very helpful thanks

The Marlec HRDi does indeed appear to be a single unit to combine solar and wind charge controller. However
- it is not clear how sophisticated the solar controller is - eg is it a full MPPT controller ? The links I found did not clarify this.
- it appears to work only with Rutland wind generators - and they are pretty heavy so unlikely to work on a demon table basis.

Thanks also William_H for your comprehensive post - though I fear much of it goes over my electrical understanding.
My rough thinking would not be to have both solar and wind connected simultaneously. For reasons of avoiding lots of fixed clutter I was toying with a demountable system where either a solar panel Or a small / light wind turbine is slotted in when needed, and choosing one to suit the weather. May be mad but seems to be the only way whilst keeping cockpit clear and windage low

 

[duncan99210]

As I understand it, solar regulators (whatever their flavour, MPPT, PWM etc) have a similar working method in that they look at the voltage of the batteries and, if the battery voltage is at maximum, they turn to solar panels off, because it doesn't damage the panels simply being turned off.
Wind regulators also look at the battery voltage and, when it is at the selected maximum value, they divert the incoming electricity to a dump load to protect the batteries. This is because if you simply turn a wind turbine output off, it removes the load from the turbine and it will rotate faster and faster until something breaks.
Now, I know that's not true for all turbines, some have a switch which turns off the output but also brakes the turbine to prevent damage but turbines like that tend to have proprietary controllers which come as part of the turbine kit you buy when you get the turbine.
So, unless you're looking at a proprietary system like Marlecs's Rutland turbines which also have a solar regulator built into the system, you're probably looking at separate controllers: wind and solar.
If you're determined to go down the route you outline, then you could use the same wiring from turbine/solar panels to near your battery bank and then have a two way switch to select the correct circuit for the regulators. The regulators themselves are fairly small, so it needn't take up a lot of room nor will it add much complexity to your system.

 

[VicS]

Very helpful thanks

The Marlec HRDi does indeed appear to be a single unit to combine solar and wind charge controller. However
- it is not clear how sophisticated the solar controller is - eg is it a full MPPT controller ? The links I found did not clarify this.
- it appears to work only with Rutland wind generators - and they are pretty heavy so unlikely to work on a demon table basis.

Thanks also William_H for your comprehensive post - though I fear much of it goes over my electrical understanding.
My rough thinking would not be to have both solar and wind connected simultaneously. For reasons of avoiding lots of fixed clutter I was toying with a demountable system where either a solar panel Or a small / light wind turbine is slotted in when needed, and choosing one to suit the weather. May be mad but seems to be the only way whilst keeping cockpit clear and windage low

You are right the HRDi is not an MPPT controller

I don't think MPPT is necessary for controlling a wind gen.
It's object is to get the most out of a solar panel because a solar panel in effect ( although it's not plain and simple ) has internal resistance and the power output rises to very distinct peak when the panel is controlled at its max power point. I think the same effect will be negligible with a wind turbine.

The HRDI controls the battery charging aspect by PWM and I believe a multistage charging regime.

 

[William_H]

You are right the HRDi is not an MPPT controller

I don't think MPPT is necessary for controlling a wind gen.
It's object is to get the most out of a solar panel because a solar panel in effect ( although it's not plain and simple ) has internal resistance and the power output rises to very distinct peak when the panel is controlled at its max power point. I think the same effect will be negligible with a wind turbine.

The HRDI controls the battery charging aspect by PWM and I believe a multistage charging regime.

Hi Vic I am going to stick my neck out and disagree with you. I think an MPPT concept would be ideal for a wind turbine for charging a 12v battery. The turbine would collectively have a similar apparent internal resistance to that of a solar panel. So in a given strong wind you would have a high voltage out if you load it up by trying to suck a large current you would slow the turbine down. (good for strong winds) Like wise a light loading gives a high voltage. So for any given wind strength there will be a max power point for taking the power out of the turbine.
Now a simple turbine with just rectifiers in the "controller" as I have seen Chinese ones will generate a high voltage at strong winds. if connected directly to a battery the current will drag the voltage down to that of the battery. Some power being lost in the internal resistance (windings ) of the turbine.
Now the turbine might only have light winds so low speed. This results in a lower no load voltage. If this does not exceed the battery voltage then you get no current in. So you have to design the alternator in the turbine to give enough voltage at low wind speed to get some charge into the battery. This design however being contra indicated for strong winds high turbine speed.
So the MPPT concept could be used to boost voltage to get some charge at low speed. While converting high voltage for high speed into more current at correct voltage for high speed strong winds.
Now I don't know enough about wind turbines on the market. Perhaps they do this but I doubt it. It is all theory on my part. Probably just like solar. Design the source for high voltage so that at mediocre conditions you still get some charge. But at the expense of less than ideal efficiency most of the time.
An interesting concept occurs to me that the wind turbine alternator could have tapped or selectable windings to automatically select a lot of turns for high voltage at low speed or less turns connected for more current still at adequate voltage for strong winds. And of course a short circuit to load the turbine in a gale.
olewill