Earth Notes: On Website Technicals (2026-07)

I want to do some quick proof-of-concept testing around plug-in solar PV now that 16WW's FiT administrator is OK with it.

As part of the test set-up today I have set up the Local Bytes smart socket both to allow disconnecting a microinverter under server control, but also to monitor the power flows.

Power flow through the Local Bytes device shows as positive, whether to or from the mains, which will complicate things a little.

As measured by the Maplin N67HH, the Local Bytes device itself seems to draw <0.1W with the relay off, and ~1.3W with the relay on. Consuming this power only when the microinverter is likely to be able to supply it seems reasonable. And manually turning everything off at the (mains) plug when excess power seems unlikely, eg in gloomy mid-winter, also seems easy and sensible.

Naturally the day that I play with this it has been overcast all morning, with direct sunshine breaking through around noon.

A small test with the better-lit (further from the apple tree) 255Wp panel via a test microinverter has ~110W (with power factor 1.0) reported by LB, with the off-grid Morningstar pulling over 50W from the other, cf ~3.4kW being generated by the grid-tied system. The sun is fairly high in the sky. Nominally that energy is helping cook my lunch pasta on the induction hob!

2026-07-14T11:38:18Z {"StatusSNS":{"Time":"2026-07-14T12:38:17","ENERGY":{"TotalStartTime":"2022-10-05T19:17:26","Total":3.085,"Yesterday":0.003,"Today":0.055,"Power":110.3,"ApparentPower":110.3,"ReactivePower":0.0,"Factor":1.00,"Voltage":245,"Current":0.451}}}

The microinverter was in direct sunshine and the red 'heat' light came on, and was probably limiting power output, though the fan was barely audible. ~12:30Z I moved it to shade.

See the raw data.

% gzip -d < img/LocalBytes-monitoring-plug/2026-07-14-microinverter-PoC/LBplug-2026-07-14.log.gz | \
    sh script/LBPowerExtract.sh
2026-07-14T08:09:02Z 0.0
2026-07-14T08:10:01Z 0.0
2026-07-14T08:11:01Z 0.0
...
2026-07-14T14:26:18Z 54.9
2026-07-14T14:27:01Z 12.5
2026-07-14T14:28:01Z 45.1
% gzip -d < img/LocalBytes-monitoring-plug/2026-07-14-microinverter-PoC/LBplug-2026-07-14.log.gz | \
    sh script/LBPowerExtract.sh | \
    awk '{s+=$2}END{print s/60}'
225.418

Thus ~200Wh was generated by the microinverter.

% gzip -d < img/LocalBytes-monitoring-plug/2026-07-14-microinverter-PoC/LBplug-2026-07-14.log.gz | \
    sh script/LBPowerExtract.sh > input.dat
% gnuplot graphing/gnuplot-LB-power-plot-v2p1.txt
% svgo -i output.raw.svg -o output.svg img/LocalBytes-monitoring-plug/2026-07-14-microinverter-PoC/LBplug-2026-07-14.svg

I have added a SUPERDUMPING output flag for powermng to signal that dumping to a larger load or transfer to grid is requested.

Super-dumping is enabled only when normal dumping is allowed, and there is PV generation (not dark), and with one of a few triggers (but no ride-through): F, V, u, E. All but E indicate strong generation that may not be fully captured by off-grid storage, thus use/transfer it or lose it.

There is a special case for 'T' to super-dump providing that the battery level is at least VHIGH.

A super-dump of ~30W would be 5Wh (about a mobile phone battery capacity) per 10 minute slot, and at ~2.5A would likely not overtax the 12V wiring.

I tweaked 'V' to be quicker to start, for the more aggressive non-LESS_DoD case in use.