Belenus (the celtic sun god) provides a closed loop solar capture, solar time shifting, energy storage and un-interrupted run use case.
As shown in the context diagram, the system consists of a number of distinct components and interconnections.
- Solar Panels capturing solar energy.
- Maximium Power Point Tracking(MPPT) Solar Charge Controller
- Lithium Iron Phosphate Battery and accompanying Battery Management System(BMS)
- Electrical Grid power
- Inverter/Battery Charger/AC Passthrough
- AC loads comsuming power
The Solar Panels/Charge Controller harvests solar energy used to charge the battery or if the battery is a 100% state of charge, feeds the inverter to power the AC loads.
The AC passthrough function may (if Electrical grid power is availalbe) feed this power to the AC loads without using any of the stored battery power.
The AC charger function may ( if Electrical grid power is available) charge the battery.
A monitoring system captures telemery or measurements of power generation, usage and storage at various points in the system. These measurements are used to provide real time monitoring dashboards and also are an input into the control functionality of the system.
The monitoring capabilities include:
- Telemetry from the MPPT charge controller that provides solar power generation metrics.
- Data from the BMS, which provides battery characteristics such as charge/discharge state, state of charge, battery voltage, current sink or draw.
- Invertor/Charger/Passthrough operating metrics
- Non invasive coil based measurement of AC circuits providing Voltage, Power, Frequency metrics.
Currently a single control point is provided in the form of an intelligent AC switch which allows for the engagement or disengagement of the Electrical grid power. With this switch it is possible to switch to using the stored battery power to feed the AC loads instead of the Grid power, this allowing for time shifting of power harvested either through solar capture or stored at a time of day with the cheaper time of day.
Sensor data from the monitoring processes is stored in an influxdb timeseries databased and is then presented using the graphana dashboarding system.
In the first Dashboard we see operation for the last three hours. The board presents the key instaneous and historic operating metrics. These include
- The last measured (instaneous) values for battery voltage and current as measured. Power calculations indicating the power either being provided from the battery or being injected (as charging) into the battery.
- battery state of charge.
- operating parameters (voltage, current, power) for the solar array and solar charge controller.
- daily and cumulative yield figures
The 7 day timescale on the dashboard shows the operating cycle of the system where the system has been charging during daytime/sunlight hours and then using that energy (currently by manual operation of AC power switch) when the battery has reached 100% state of charge or by configured control of the AC power switch from 4pm to 9pm ( future high cost time of date cost period from utility provider)