Redundant Xantrex PV system

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  • Joe_B
    Joe_B Solar Expert Posts: 318 ✭✭✭✭✭✭
    #32
    Re: Redundant Xantrex PV system
    stephendv wrote: »
    Crazy? It sounds awesome :D For off-grid systems I think an intelligent brain type system could make a few clever decisions like managing optional loads and generator starting. The kinds of functions I'd like to see in a such a device would be:
    • If the generator is on, and the load is less than 50%, then turn my well pump on.
    • If the batteries are at 60% State of charge and the weather forecast is for clouds all day, then turn the generator on early in the morning.
    • If the batteries are in float and there's surplus solar power, turn the well pump on
    • Reprogram my morningstar MPPT to perform a short charge to reach 2.65V for 5 minutes after being in absorb for 3 hours, every 2 days.

    For the SMA kit, they've released an open source API for windows and linux called YASDI, which can be downloaded from http://www.sma.de/en/products/software/yasdi.html with it, you can talk to every SMA device.

    Hopefully the management of S is listening :roll:
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  • Dr. Strangelove
    Dr. Strangelove Solar Expert Posts: 49 ✭
    #33
    Re: Redundant Xantrex PV system
    stephendv wrote: »
    Crazy? It sounds awesome :D For off-grid systems I think an intelligent brain type system could make a few clever decisions like managing optional loads and generator starting. The kinds of functions I'd like to see in a such a device would be:
    • If the generator is on, and the load is less than 50%, then turn my well pump on.
    • If the batteries are at 60% State of charge and the weather forecast is for clouds all day, then turn the generator on early in the morning.
    • If the batteries are in float and there's surplus solar power, turn the well pump on
    • Reprogram my morningstar MPPT to perform a short charge to reach 2.65V for 5 minutes after being in absorb for 3 hours, every 2 days.

    Wow, you don't ask for much! I suppose these kind of criteria are easily expressed in PLC terms. Some framework like this would necessarily underly the automated transitions between modes of operation based on measured parameters.
    For the SMA kit, they've released an open source API for windows and linux called YASDI, which can be downloaded from http://www.sma.de/en/products/software/yasdi.html with it, you can talk to every SMA device.

    Thanks for pointing that out. Unfortunately it looks like the unfinished work of an intern - it resembles the code I wrote when I was a junior. Possibly two interns, over two different Summers (I hope for their sake, it is not SMA's engineers' paid work product). It is a "kind of" userland driver stack, with no information about the devices to be controlled. The only other information I have found is the "SUNNY WEBBOX MODBUS-Interface User Manual" and "SUNNY WEBBOX MODBUS Interface Technical Description" which are interesting but I think incomplete - is there a better reference? The Xantrex Gateway has (or was to have) similar functionality (I think its utility was crippled by the pathetic choice of user interface). Interestingly, they both seem to support ModbusTCP through proxying, but I can't determine if they might limit access to the devices on the Modbus side. However, each device costs as much as a good PV panel or two. When will manufacturers' pointy-haired bosses realize that the "system glue" is NOT a profit center? If they were to virtually give away these devices, then resellers could more easily sell complete systems and customers could maximize the utility of their purchase. It's not like they could be used for anything else. But no, management sees these interface boxes as low volume and high development cost - hence low priority options - making it a self-fulfilling prophecy.
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