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Fantasy Solar League, money no object

  • 18-08-2023 7:49pm
    #1
    tonysopprano
    Registered Users, Registered Users 2 Posts: 841 ✭✭✭


    Anyone interested in contributing, as I believe that a lot of my questions should be in sticky's.


    1) Can a single inverter handle 3 strings, if I have roof space for panels on 3 (or 4) aspects, if I keep the panel count down to 22 or 24 (that I believe to be the max eg 7 or 8 panels on an E/W/S aspect?

    2) If answer above is no, can a single/multiple/series/parallel battery system be supplied by multiple inverters

    3) Is it better to have 1 x10 Kw battery or 2 x 5Kw batteries in serial/parallel

    4) Which inverter offers the best charge/discharge rate (my research says Givenergy or Sunsynk)

    5) For powercut or off-grid should I go for Low Voltage or High Voltage systems

    6) Should I get Solar Thermal (best return/value option I believe) or EDDY

    7) Can you mix batteries eg LiFEPo4, LeadAcid and Lithium (if you happened to have access to all)

    8) Should you go for an AC or DC battery system (TESLA, Powerwalls and any newer entrants including Solar tiles etc)


    As stated in the heading, this is not about money or quotes but just about aiming for best and designing the best possible systems and letting people then pick and choose those elements that suit them


    Would love for the experts to chip in, stating their reasons and collate results.

    Apologies, if in the wrong place

    If you can do the job, do it. If you can't do the job, just teach it. If you really suck at it, just become a union executive or politician.



Comments

  • #2
    TerraSolis
    Registered Users, Registered Users 2 Posts: 129 ✭✭TerraSolis


    1) Yes, there are inverters that have three MPPT inputs but they are usually large 20 kW+ three phase inverters. Another option is to use optimisers and string combiners to allow a dual MPPT inverter to handle additional orientations.


    2) Yes, two or more compatible hybrid inverters (typically same make and model) can communicate to operate in parallel and share a battery bank.


    3) Swings and roundabouts. 10 kWh battery extremely heavy to move into place. 2 5 kWh means more cabling and needs busbars to combine them in parallel if it doesn't have additional terminals for paralleing. Etc. Etc.


    4) Your research is well informed. Some SOFAR hybrids have decent charge and discharge too but the Deye/Sunsynk offer higher. However there's only so much power you can/want to draw from e.g. 1 10KWh battery. For very high charge and discharge, build a larger battery bank.


    5) HV systems are more efficient (less "round-trip" losses than LV). LV are more compatible with different ranges of equipment if you want to add more in the future as they tend to be a common voltage (48V (well, 52V in reality)) whereas the HV setups can be 96, 200, 300 V etc. depending on the kit. I like LV because it's more Hackable, but the high currents at LV can be problematic if you get too ambitious.


    6) Solar thermal is a cool and underrated tech IMO, but economically speaking it gets its ass kicked by PV these days. If you get Solar thermal, do so as an interested hobbyist. If you just want max bang per buck, go with PV. The Eddi gets bashed on here for the cost quite a lot, but I like it. The export payment will collapse in the future and the eddi will be very useful then.


    7) NO. Not wired in parallel. They can be connected separately to separate non-paralleled inverters, but you cannot mix them together as part of the same battery bank. Frankly, forget lead-acid.


    8) I like DC because it can absorb power even when your inverters are maxed out on an AC basis so you can connect more solar than ESBN want you to connect on an AC basis. Additionally, the inverter on an AC battery will take up some of your NC6/NC7 allowable inverter capacity. But AC battery can be easier to integrate/talk to other power equipment using a CT clamp. However, the keen nerds amongst us can manage that using MODBUS style controls anyway.



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