Nano Power Inverter - Roll Your Own Style

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Joined: 21/06/2018
Location: Australia
Posts: 951
Posted: 12:58pm 30 Mar 2023      

  Murphy's friend said  Mike, you might want to think about that all on one a single trolley idea.

Klaus, let me assure you I have thought (agonised?) about the trolley idea a lot !

My application and direction is rather specific at the moment for at least the next year or two.

I have the Sirius 3.6kWH storage unit which weighs ~ 65kG & will be on the bottom shelf, it measures 55cm x 65cm x 20cm.

Next shelf up will be the Battery Charger and some other "stuff".

In my application all the items will be wired together and the trolley location can be easily changed.

The GTI will be mounted vertically at one end of the trolley and the nano inverter will be on the top shelf.

The trolley frame which is being currently built will be ~ 800mm high ~600 deep and ~ 650mm wide

It is just for proof of concept at this stage and my intention is not to disconnect from the grid yet as I can still get a return for my excess power. Today at around noon we were only generating ~ 8.5kW and we were consuming a whole ~450W.

I intend to AC couple my battery storage to feed my house requirement if the roof solar is offline or not generating enough for our needs (think night or heavy cloud) but not to feed any of the battery storage to the street grid at all.  When solar resumes before feeding 1W back to the grid I will fully recharge the Battery unit first.

I estimate the total weight will be ~ 150kG + the trolley weight.  I already have some surplus castors that should easily handle that weight.

  Murphy's friend said  Your other (over complicated ) idea of switching two cores in parallel, or not as power demands, is something I would not consider at all.

For a start, you need two heavy primaries to be switched as well, which complexity and expense would surely negate any saving from miniscule idle current gains.

13.5W from 7pm until 10am is ~ 200WH not much for 20kwH (~1%) but for 3.6kWH (~6%)

If I use a second inverter power stage driven by the same controller there is no need to switch the second primary I just enable the second power stage drive, but that needs to first have the second transformer degaussed before connecting it directly in parallel with the mains output of first transformer. Piece of cake!

Making this work is quite straightforward for me but I wont rush into it, I tend to play devils advocate in my head for quite a while before starting something.
Also for now, I am only planning to use the nano inverter if the grid actually fails as it will need a few switches to be thrown first (disconnect grid join L1,L2,L3 in parallel etc.

The conserving power is more academic at this stage and if and when I get some bulk storage and disconnect from the grid (and gas) then I may not care as much anymore, I just like stuff running as efficient as possible if its just a matter of a bit of time and a few more bits when I already have probably 95% of what I need in my "stuff".  The real fun will begin when I use the nano inverter to commutate the GTI's and toss the grid for good - when I start to receive power bills again which with the reducing tariff is probably not too far off, I will get more incentive to finally disconnect.  I haven't had to pay a cent for power since Dec 1999, for an initial outlay of ~ $9K.

In summer on a typical day we generate ~ 85kWH/day, 13.5KW of panels & 10kWGTI. It paid for itself ~ 1 year ago.