Difference betweek Windy boy and Sunny bBoy inverters

[jotec]

Hi,
I need a GTI got the CHP project. I am hoping to get something second hand.

Q - What is the difference between the sunny boy and windy boy inverters. Both seem to have maximum DC input of 600V and both start tot function around 240v DC.

Ideally i would like to be confident that I can buy either and connect it to a (rectified) PMA for grid tie.

Dick

[Outtasight]

Can't speak for all the SB/WB range but when I was looking at getting a SB1100LV they said they were discontinuing it as a model but that I could have a WB1100LV and just have the firmware tweaked to use it on solar. 

They are in fact the exact same model. Only at the factory they set the WB to "wind" mode and the SB to "solar MPPT" mode and put a different label on the front of the unit.  The two units even share the same firmware.  It's just a setting in the software that is read at start-up.  For some reason though it's not a user configurable setting and the dealer wanted to charge £50 to connect the service computer and toggle the setting.

Wind mode has a set voltage-current profile curve (you can user edit this profile to suit different generators).  The solar mode uses automatic MPPT and is only suitable for PV.

[jotec]

Thanks for that Outtasight

I am still not sure.
The MPPT,as I understand it sorted, 'sorts' the voltage and current to suit the panel voltages. (I thought just for battery charging)

If tmy generator is at a steady voltage then the MPPT would just alter the voltage to what it wants then again to mains? (or am I miss understanding this?)

My main concern was what difference was in the hardware. If there is no difference that is good.
Dick

[Outtasight]

The MPPT software will periodically scan the I-V curve of the generator from no load to short circuit (as that's how it figures out the maximum power point of a PV panel).  Generators don't like running with no load.

MPPT acts like a transformer (in fact it is a DC-DC converter working at high frequency with a small transformer). 

Inverters also have an ideal working voltage (same as batteries) and so the MPPT transforms the varying input DC voltage to a fixed output DC voltage that the inverter section works most efficiently at.  It also allows the input DC voltage to match the working voltage of the PV modules.

Generators have very different I-V curves from PV panels and will just confuse the scanning MPPT software into latching on to some weird input voltage.  Their output also changes too quickly for the MPPT software to scan (especially wind machines) so in the wind mode it uses a pre-programmed I-V map that the user inputs with data for the specific generator being used.

[jotec]

Now it makes sense. Thanks.

Where did you get the £50 quote to change from SB to WB? (or would it have to go back to Germany?)

Dick

[Ivan]

You can change from WB to SB configuration simply by using the free SMA software and a communications lead (or powerline modem, or wireless etc).

You'd be better off with 'Konstant' voltage mode for your generator, I think (this is another option you can configure via the software)

[jotec]

Thanks Ivan,
I hoped it would be something like that.
How is your CHP progressing?
D ick