DC Microgrid Demonstration Panel with Solar and Battery Inputs

Most modern loads are natively DC — LED lighting, electronics, chargers, battery storage — and rooftop solar generates DC as well, which is why DC microgrids are moving from research papers into real buildings and rural electrification. But a microgrid is more than solar plus battery: it must decide which source serves the load at each moment, keep the bus voltage stable during changeovers, protect the battery from over-discharge, and make all of this measurable. This panel is a bench-scale 12 V DC microgrid that does exactly that on copper bus bars — solar through a PWM charge controller, a sealed lead-acid battery, and a mains-derived DC backup — with selector switches, branch meters and a load bank that turn every power flow into something the student can see and measure.

1. The solar panel feeds the PWM charge controller, which charges the 12 V battery and supplies its load output with overcharge and deep-discharge protection.
2. The battery, the controller's load output and the mains-derived DC adapter each connect to the positive and negative copper bus bars through selector switches wired for priority.
3. With good sun, the solar branch carries the load and charges the battery; the branch meters show the solar current dominating.
4. When the panel is shaded or disconnected, the battery automatically becomes the source, and its meter shows the discharge current.
5. If battery voltage falls toward the disconnect level, the mains-derived adapter takes over so the load bank never goes dark.
6. Switching the lamp loads in and out shows how bus voltage responds to loading, and the meters quantify each source's share through every transition.

Tech stack:

• 12 V solar panel, approx. 20 W (demo size)
• 12 V 7 Ah sealed lead-acid battery
• 20 A PWM solar charge controller
• 2× digital DC voltmeter/ammeter panel meters
• Copper bus bars with brass terminals
• Selector toggle switches and 12 V lamp load bank
• 12 V 2 A AC-DC adapter (mains backup)

• [Three-source 12 V bus] Solar panel, 12 V 7 Ah battery and mains-derived DC adapter meet on copper bus bars — the physical analogue of a microgrid's common DC link.
• [Source-priority switching] Selector wiring implements a priority order: solar first, battery when solar fades, mains backup if the battery runs low — the core microgrid dispatch decision in hardware.
• [Solar charge controller] A 20 A PWM charge controller manages battery charging with overcharge protection, the same device family used in real solar-home systems.
• [Per-source metering] Digital V/A meters on the solar and battery branches show live voltage, current and implied power, so the contribution of each source is always visible.
• [Switched load bank] Three lamp loads switch individually, letting learners vary bus loading and observe voltage behaviour under light and heavy load.
• [Battery low-voltage disconnect] The controller's load management protects the battery from deep discharge, demonstrating storage protection.
• [Live changeover demo] Shading the solar panel triggers a visible source transition on the meters — the microgrid's defining moment, shown on demand.

• Fully wired demonstration panel (solar panel, battery, controller, bus bars, meters, load bank)
• Source-priority wiring and configuration guide
• Battery care and charge-controller setup notes
• Test procedure (sun/shade transitions, load steps, changeover timing)
• Complete wiring diagram and schematic
• Project report PDF (background, microgrid theory, methodology, observations)
• PPT presentation for final review
• Viva Q&A preparation document (MPPT vs PWM, bus stability, battery protection, dispatch priority)

• The panel is a low-voltage demonstration microgrid; it does not export power to the AC grid and has no grid-tie inverter.
• Changeover is switch/relay-based at demo scale — seamless solid-state transfer and bus-holdup design are future scope.
• The PWM controller is less efficient than MPPT; the documentation compares the two honestly and lists MPPT as an upgrade path.
• Battery runtime at full load is limited by the 7 Ah capacity — load-bank experiments are sized accordingly in the test procedure.
• Outdoor solar measurements depend on actual sunlight; the procedure includes a lamp-based indoor alternative for repeatable demos.