Monthly Archives: October 2025

Outbuildings: Week 34, Day 5

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Outbuildings: Week 34, Day 5

Close to zero progress on the Groundworks, after concluding the precast concrete headwall delivered yesterday – with a much larger pipe aperture and protective grating than specified – can’t be used, so needs to be replaced.

The team from Carbon Legacy were back on site to complete the installation of the Tesla PowerWall 3 system, which was finished by lunchtime. All of that seems to be working well – including the 90m Current Transformer clamp connection back to the House, to let the PowerWall monitor the generation from the existing AC-connected solar PV system – and the temporary hook-up of a wired network connection for the PowerWall (which happily connected at 1Gbit/s).

For now the PowerWall monitoring is purely a ‘real time’ display via the Tesla smartphone App; I need to investigate the options for API access and integration into Home Assistant.

The outdoor unit for the air-to-air heat pump was due to be delivered today, but that will now arrive tomorrow. The team from Chellaston Renewables dropped off the three indoor units which they had previously collected from the distributor, ready for installation to start over the weekend.

Outbuildings: Week 34, Day 4

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Outbuildings: Week 34, Day 4

The main event today was the start of the installation of the Tesla PowerWall 3 solar inverter and battery storage system, to connect to the solar panels which were installed in August. Much of the work was in the outdoor GRP cabinet, which houses the Backup Gateway that is responsible for taking the site “off grid” in the event of a mains supply outage – so it pretty much has to be installed adjacent to the main meter. Earlier measurements had confirmed there was just enough room for it inside the cabinet.

The main PowerWall 3 unit, which is a combined inverter and battery storage unit, was always destined for installation in the Plant Room, which is (intentionally) the nearest part of the building to the GRP cabinet. In order to add further storage capacity there will be two battery expansion packs – although only one was installed today, due to space and weight limitations on the installers’ van.

Tesla “Backup Gateway” installed adjacent to the DNO cut-out and SMETS2 meter
The main Tesla PowerWall3 unit (on the right) and one of two battery expansion packs (on the left)

While installing the Backup Gateway, mains power was disconnected from the House for almost 5 hours, which was far too long for the Uninterruptible Power Supply in the House to continue powering the IT network equipment and CCTV cameras, resulting in the 12:00 webcam snapshot which is normally automatically uploaded as the daily overview image being missed – so the 11:00 snapshot was manually uploaded instead.

There was also further progress with the groundworks – although somewhat delayed by the mains power being off, meaning that the pump that was going to be used to clear the water from the drainage trenches couldn’t be cleared until power was back on after 3pm.

The long-awaited concrete headwall – the replacement for the one that was due yesterday but got damaged in transit – was delivered, although with some difficulty using the small-ish digger on site. It turns out this was far from a direct replacement for the one that was ordered, since it is sized for a 450mm diameter pipe, not a 150mm diameter pipe – and it has the wrong specification of protective grid on the outlet.