Su-Kam 6.25KVA/96V Off-Grid Solar PCU: How India's Smartest Rooftop Solar System Worked

A Solar PCU — Solar Power Conditioning Unit — is an independent, integrated off-grid solar system. In a single box it combines three things: a solar charge controller, an inverter, and a grid charger. You connect solar panels on one side, a battery bank and your home load on the other, and it manages everything automatically — prioritising solar, protecting your batteries, and giving you 230V AC just like a normal wall socket.

The 6.25KVA/96V model was one of Su-Kam's flagship rooftop systems. This blog breaks down exactly how it worked, based on the original product demonstration.

Watch: The Full System Walkthrough

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Solar Panel Wiring: How to Connect 6kW at 96V

The 6.25KVA system is designed to work with 24 panels of 250W each — totalling 6kW of solar capacity. Wiring them correctly to achieve 96V requires a specific series-parallel arrangement.

Start by connecting 4 panels in series. Each 250W panel produces 24V, so 4 in series gives 1kW at 96V. That's one array. Repeat this to make six identical arrays, then connect all six arrays in parallel. Parallel connections add current but keep voltage constant — so you end up with 6kW at 96V, which is exactly what the Solar PCU needs.

Battery Bank: 8 Batteries in Series

The 6.25KVA/96V Solar PCU connects to a 96V battery bank — built from eight 12V/150Ah batteries wired in series. Series wiring adds voltages while keeping capacity the same, giving you a 96V/150Ah bank. For more backup time, you can use 300Ah batteries instead.

Inside the Solar PCU is a 45A MPPT solar charge controller that efficiently charges the 96V battery bank from solar panels, plus a separate 30A grid charger that charges from mains when needed.

What Can You Run on 6.25KVA?

A 6.25KVA system can power a substantial home or small business load simultaneously:

India's First Solar PCU with Solar kWh Display

The LCD display on the front panel showed system parameters in real time: output voltage, load percentage, PV voltage, and battery voltage. But what made this unit distinctive was one additional feature: it displayed solar energy generated in kWh and PV current in amps.

This was India's first Solar PCU to do this. It meant any homeowner could track their solar panels' daily performance and calculate their monthly electricity bill savings directly from the display — without any external meter or app.

Two Priority Modes: Choose How Your Load Runs

A DIP switch on the back panel (Switch #3) lets you choose between two priority sequences. Both always give solar the highest priority — what differs is the fallback order.

To illustrate Mode 1 in action: suppose your load is 4kW and panels are generating 6kW. The system runs the 4kW load from solar and charges the battery with the remaining 2kW. If panels drop to 3kW, the system takes 3kW from solar and pulls the remaining 1kW from the battery — it does not reach for the grid yet. Only when the battery reaches its lower threshold (89.6V) does mains connect.

Day Mode and Night Mode

The Solar PCU automatically switches between Day and Night mode based on PV voltage. When PV drops below 50V, it enters Night Mode and runs the load from battery or mains. When PV rises above 50V and exceeds battery voltage, it enters Day Mode and switches back to solar — running the load and charging the battery simultaneously.

Wide and Narrow Mains Window

DIP switch #2 sets the mains input voltage window:

• Wide window (160–280V): For ordinary appliances — fans, lights, bulbs. Tolerates more grid voltage fluctuation.
• Narrow window (180–260V): For sensitive equipment like laptops and printers. Tighter range means faster changeover from mains to inverter, which is better for IT loads.

No-Load Shutdown: Protecting Battery at Night

DIP switch #1 enables a No-Load Shutdown feature. If the connected load drops below 40W for more than 5 minutes — say, late at night when most lights are off — the Solar PCU shuts off its output automatically. This prevents the inverter's own internal circuits from draining the battery overnight through idle power consumption.

If you need to run loads smaller than 40W (a small charger, a night lamp), you can disable this feature by switching DIP #1 to the left position.

What Made This System Stand Apart

In one integrated box, the 6.25KVA Solar PCU delivered: MPPT charging, genuine off-grid operation, user-selectable priority modes, automatic Day/Night switching, mains window selection, no-load shutdown, and a real-time display showing solar kWh generated. No separate charge controller, no external monitoring device, no switches to flip manually.

It was, at the time, the most complete off-grid solar product available in India for residential rooftop use — designed to work in any Indian power environment, from areas with stable 24-hour supply to those with eight-hour daily outages.