Earth Notes: 16WW Energy Systems Diagrams

Updated 2025-03-01.
Energy subsystem diagrams including microgeneration and storage at 16WW. #energy #microgen #storage
A central location for schematics of current (and former) energy systems at EOU Towers.

Not in this page:

Note that extensive logging and processing of real-time and historic data from all energy subsystems is performed on Raspberry Pis.

Some current energy system settings are made available automatically.

Grid-tie Solar PV System

Summary: current capacity ~5kWp(e), ~4.5kWp(e) G83 inverters, AC-coupled, half east-facing, half west-facing, slope ~23° in each case.

Read more on the (first round of the) installation.

The electrical schematic (circuit diagram) for first 1.29kWp (2008).

The electrical schematic (circuit diagram) at expansion to 3.87kWp (2009).

The electrical schematic (circuit diagram) at expansion to 5.16kWp (2010).

20100415 3rd round schematic 5p16kWp excerpt
Solar PV 5.16kWp generation system as of 2010-04-15.

Merit order

As of there is a 'merit order' of grid-tied PV generation use, best first:

  1. Direct consumption in the house.
  2. Absorption by the Enphase AC-coupled battery up to kW/kWh capacity (~1/~5).
  3. Power-limited spill to grid (up to ~400W).
  4. Diversion via myenergi Eddi:
    1. To the Sunamp Thermino heat battery up to kW/kWh capacity (~3/~7).
    2. To the DHW cylinder up to kW/kWh capacity (~3/~6). Takes priority over Thermino when a pasteurisation cycle is pending.
  5. Spill to grid. G83 limit / G59 was waived by DNO, so nominally unlimited but in practice ~4kW maximum.

Essentially nothing is spilled to grid or diverted during the winter.

Enphase Storage System

Summary: current capacity ~5kWh(e)/~1kW(e), AC-coupled.

Read about the Enphase AC Battery Grid-connected Storage in Our UK Home then Enphase AC Battery #2 then #3 and #4.

Enphase Energy Storage Diagram
Generic Enphase (UK) installation schematic, courtesy of Enphase via Eco Partners. Note that 16WW for example has two separate PV subsystems with their own meters for separate Feed-in-Tariffs; the Enphase solar monitoring clamp fits on after the circuits merge after the meters to be able to measure aggregate generation. As of the end of 2021, 4x AC Batteries to ~1kW/5kWh are installed on the storage branch.

See also PDF original, courtesy of Enphase via Eco Partners.

Heat-pump, Eddi PV Diverter and Thermino Heat Battery

Summary: Thermino capacity ~7kWh(h) down to 50°C, ~10kWh(h) total to cold ~10°C, heat pump DHW cylinder capacity likely ~6kWh, 3kW(e) peak charge rate.

See the heat pump configuration.

20250121 plumbing schematic hand drawn on whiteboard
Plumbing schematic hand-drawn by engineer (thank you!) TRV = temperature relief valve, PRV = pressure relief value, CYL = DHW cylinder, vertical dotted black line is the corner at back right of cupboard, ABY = automatic bypass, AAV is automatic air valve, C (black) and H (red) are cold from mains and hot to taps (DHW), green is radiator loop cold/return side and red is warm/flow, Rad F and Rad R are radiator flow and return to upstairs, Ra F and Ra R are radiator flow and return downstairs, Pri F and Pri R are primary flow and return from external unit, Volu is volumiser, Exp V is expansion vessel, Mag Filter is the magnetic debris filter in the radiator circuit. Click to expand image.
20250121 radiator circuit isolator valve 1 at back of cupboard 20250121 radiator circuit isolator valve 2 at right of cupboard
Images in order (click to expand): (1) first radiator circuit isolator valve (back); (2) second radiator circuit isolator valve (right).
DHW schematic v3
Pending heat-pump and heat-battery integration (v3). The thin pipes are the vanilla heat-pump only DHW system before the heat battery is re-integrated. X is a closed valve, O is an open valve. I1 is the immersion heater driven from the Eddi output 1 (connected as of ), I2 from Eddi output 2, and HP is the heat input coil from the heat pump. Non-return valves, expansion vessels, etc, omitted for simplicity. As of the Thermino/Intasol is not reconnected.
20250226 Thermino pipework landscape DM
Thermino heat battery DHW pipework schematic (by DM ). Bottom left box is the Thermino. Tall DHW cylinder on the right. Mini expansion vessel (and pressure relief valve, not shown) top middle. Intasol in the middle half-way up. See original PDF. Also see the Thermino and heat pump systems diagrams.

The Eddi has an external current clamp deployed at our meter tails to measure total flow in and out of the building, connected to CT1 terminals. As of the CT2 clamp is on the heat pump supply.

Read more on the Thermino heat battery installation including the older DHW system schematic.

See the Eddi Solar PV Diverter Top-up Dataset.

Note that the Eddi and Thermino are partly managed remotely as of to via Raspberry Pis to:

As of the Eddi controls the DHW cylinder immersion heater to perform pasteurisation cycles.

: see Reconnecting the Heat Battery.

Off-grid Solar PV System

Summary: current capacity ~1kWh(e) usable, ~0.7kWp(e) PV, DC-coupled.

main changes made; 510Wp 30Vmp in place
Off-grid PV system with storage as of 2016-08-05. [PDF]

Off-grid system notes:

Note that the Internet router is powered from the mains via a (12V) adaptor, which also has a 5V USB output. The adaptor also has a 12V-nominal input from the off-grid system, but preferentially uses 240V mains. When the off-grid system is in a good state, a 'dump' signal from the RPi disconnects mains from the adaptor with a relay, forcing the adaptor to draw from off-grid and act as a dump load. Thus the off-grid system acts as a huge UPS for the router too. The adaptor has at times driven more/other loads than the router. All recent 16WW routers have been 12V supply at ~1A; far more power-hungry than my MacBook Air as of 2023.

See Expanding and Optimising Off-grid PV for Mid-winter.