Summary: capacity ~7kWh(h) down to 50°C, ~10kWh(h) total to cold ~10°C, 3kW(e) peak charge rate. Generic schematic for (myenergi eddi) diverter, Sunamp Thermino and gas combi boiler in correct configuration for 16WW. (Extract from Sunamp PDF, with permission.) This autonomously deals with PV diversion when the system is spilling 'excess' PV generation to the grid. Some static adjustment of eddi parameters helps maximise grid-friendliness while reducing gas use in summer. Note that a dedicated RPi requests the eddi to provide boosts from the mains when carbon intensity is low enough and the Thermino is empty enough. This helps reduce gas use in winter while reducing the carbon emissions for DHW. The opportunistic use of 'excess' PV and low-carbon grid electricity to displace some gas use for DHW makes this a 'hybrid' or 'cross-vector' system.
The Eddi has one external current clamp deployed at our meter tails to measure total flow in and out of the building, connected to CT1 terminals. As of there is a spare/unused external current clamp connection, CT2.
Note that the Eddi and Thermino are partly managed remotely as of 2022-08 via Raspberry Pis to:
Provide overnight boost to the Thermino when grid intensity is low.
Pause diversion/boost in any minute when grid frequency is low.
Current Off-grid Solar PV System
Summary: current capacity ~1kWh(e) usable, ~0.7kWp(e) PV, DC-coupled. Off-grid PV system with storage as of 2016-08-05. [PDF]
Off-grid system notes:
The top set of panels at the west of house may be missing ~40W amorphous, ie should be 2Wp (amorphous) + 40Wp (amorphous) + 60Wp (multijunction).
The RPi2 is powered via an efficient hard-wired car USB adaptor (previously a stand-alone switching regulator), stepping the 12V down to 5V, with short leads to help handle demand spikes.
2022-09-09: 13:00Z: 100Wp panel was connected to the PWM side via a Schottky blocking diode.
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.