Overview

In many parts of the word, OFF-THE_GRID solar home installations are usually crude and unreliable. Solar setup depended on the skills and knowledge of DIY installers or hobbyists. Usually, homes who have solar panel setup have to manually switch to other sources of energy – such as battery or gas generator, when the sun goes down. For users who requires an uninterrupted supply of energy day or night, rain or shine; solar becomes an unattractive option.

Enter the EM100 Solar Management System. The purpose of the EM100 is to provide and uninterruptible supply of energy to a load by managing a solar source and backup sources. The goal of its design is an adaptable and easily configurable solution for off-the-grid solar installations.

The EM100 can be setup to respond to specific thresholds so that it can anticipate when the solar supply is in decline and turn on a backup source to continue to support a specific load. When sources are controlled automatically, energy management is optimized such that the solar energy utilization is maximized and non-renewable source utilization (such as gas generator) is minimized.

Threshold Threshold is the minimum power level of a source to sustain a load.

Example. Load requires 100KW 6 Panels with Max output 50KW each.

Total max output: 6 x 50 = 300KW Threshold = 300KW / 100KW (load) = 33.3%

Note: Threshold can be lower if battery is configured parallel to solar (combined) to supply output. As long as battery in-rush current is accounted for.

System Design Requirements:

1. Reliable – Must run for years error free.

2. Configurable – Solar and battery thresholds must be configurable, must have provisions to define 4th source.

3. Smooth Operation – No glitches that will damage sensitive loads.

Constraints:

1. Total power consumption must be less 150mA at Vin=5V.

2. Source switching must respond with in 500mS.

TEST CASES and Validation

Group 1 – Functionality

Solar as main Source – switches to solar in all conditions if solar > SOLAR_THRESHOLD and STAT=RUNNING and not faulted.

Battery is secondary source – switches to battery if solar < SOLAR_THRESHOLD && battery > BATTERY_THRESHOLD.

Generator pin on when solar + battery (source1, source2) are below their thresholds.

RESET – System = OFF

START (UP Joystick) – Starts system running

STOP (DOWN Joystick) – Stops system

Group 2 – Indicators and displays

LED1 – Blinks (running)

LED2 - SOLAR (Source1)

LED3 – BATTERY (Source2)

LED4 – GENERATOR (Source3)

LCD Must display source levels at all times.

LCD must display Status and source at all times.

LCD must display time since source have started.