Got a call from Lachlan yesterday around this time - they’d had a cancellation I think, and they could come today if we wanted. Sure, that works for me! I quickly went out last night to move all the crap from around where the inverter would go, and made sure everything was teed up… as it turned out, I worked a bit last night and the night before, and had to go in early this morning for a meeting, so I had some extra time so I could jet early if they had to turn the power off.
They got here around 7:30 and started unloading things, and by about 10 they were in full swing putting the racking up on the side of the house. A friend had mentioned Fronius’ research some time ago about putting a single string on different facing roofs working out fine as long as both sides were the same number of panels, but we ended up not being able to do that anyway - the number of panels would not have been equal and I would have to give up some. So instead we stuck with the plan - one string on the east facing roof, another on the south. When we eventually get rid of all the cooling systems and replace them with a single refrigerated ducted AC, we’ll be able to put double that number of panels on (and then some, there’s some space on the south roof avoided solely because of shadows), but for now the roof shape is terribly inconvenient with shadows everywhere to make that happen.
Anyway, I clocked off work at about 2pm, expecting the power to be off soon. They turned it off about 3pm, and it was off for just short of an hour as there was quite a bit to do in our switchboard (which is an absolute mess, and Baz will clean it up at some point and replace the single RCD with individual ones, as well as cover the lights in RCDs as well). The UPS handled about what I thought it would, it got down to about 40% battery in about 45 minutes before I shut down both servers to preserve internet access.
Everything came back on, and they started setting up the inverter. We must wait for the inspector to come out before we’re allowed to connect it, but in just the 20 minutes or so that it was on to get configured, it generated (but eventually dumped, I think) about 1.8kWh, or right around 15c AUD at our current feed-in rates. Not too shabby, particularly for about 6pm with mostly east-facing panels!
So in the end, including the old 2kW system, we’ve got a Fronius Primo inverter, and Suntech STP-370s panels, giving us around 10kW of inverter and about 11 or so kW of panels in optimal conditions. Naturally about half that will not be doing much for a good portion of the year in winter, but I’m optimistic that in the summer months we can rack up a good credit to carry us through the winter months, particularly with not running electric heating any more.
Now to just wait for the inspector to OK connecting it to the grid, and then we can start observing the data and see how we’ll end up.
Update: 2022-03-07: The installer specifically left the DC turned off, but the AC supply turned on so the inverter would be present in our home network and I could look at monitoring it. The smart-meter it’s connected to in our switchboard is also functional, and I was able to take a look at setting up monitoring for it and… oh my god do Fronius make this easy!
It has an unauthenticated (the browser sends auth, but it’s not required) endpoint at
/solar_api/v1/GetPowerFlowRealtimeData.fcgi which returns a nice JSON dict. I went to see what my options were for having collectd poll it, and sure enough there’s a
curl_json module which is purpose-built for exactly what I want. Why, it took longer to add the
curl modules to my collectd container than it took to configure it and start pulling data!
To have a complete picture I still need to figure out how to monitor the old inverter because at the moment there’s up to 2kW of noise between what we’re generating and what we sell/consume, that’s simply the variable amount the old array is generating that’s currently unknown. But that’s a problem for another day.
Update: 2022-03-09: Electrical inspector’s been and gone, signed off on it, and activated the DC side. We started out immediately banging up against the export limits at about 10am, not coming down off the export limiter (except for minor periods during cloud cover) until just before 4:30pm, meaning that for most of today just about anything I turned on will be completely free… so I’m pretty happy with it so far! Today was an uncharacteristically clear day, but what I’m super impressed with is that even when there was some very heavy cloud cover (as in, my office got quite dark and I went outside to inspect it) we were still selling electricity and not buying any, so depending on what effect a low angle of the sun has on the whole setup, this winter could be interesting to say the least.
I did remember that I’m supposed to notify our electricity retailer of any changes to the PV system - doubly concerning because before we switched to them I mentioned that we were going to upgrade the system, and they agreed to waive the 5kW system limit. I remember when I signed up they’d changed the limit to 100kW (for some reason) but I can’t find any record of that, only in the email that they agreed that my quoted 6.6kW system would be fine. That last bit’s problematic, because the new installed capacity is over 10kW, and I couldn’t find any proof that they’d changed it to 100kW, so we might be in some grief.
So I was sweating bullets that we’d have to find a new retailer (and thus lose about 20% of our feed-in rate) but they wrote back some hours later giving me the OK, and apparently they raised that limit some time ago anyway. So all good, let’s see how it performs over the coming year!