SU-KAM FOUNDER SERIES · PART 08

Su-Kam 1KVA/24V Solar PCU PCU1K24 — India’s first Solar Power Conditioning Unit under Kunwer Sachdev

India’s First Solar PCU Was Built by Su-Kam — Under Kunwer Sachdev

When almost no one in India was focusing on solar, Su-Kam built the country’s first Solar Power Conditioning Unit under Kunwer Sachdev — filed the first technology patents under his leadership, started with PWM-based designs, moved to MPPT-based Solar PCUs, learned from every installation, scaled to 100 kVA three-phase, and exported the highest volume of solar PCUs from India from 2009 to 2018.

By Kunwer Sachdev · Su-Kam Founder Series, Part 08 · हिंदी: इस लेख का हिंदी संस्करण · Archive: 1KVA Solar PCU R&D deck (Tarkeshwer Gautam) · Related: Part 02 — TFT Touchscreen Solar PCU · Part 06 — India’s First MPPT · Part 07 — India’s First BMS

A Solar PCU is not an inverter with a solar sticker. It is the box that decides when to run from PV and battery, when to lean on the grid or DG, how to protect the pack, and how to prove what the plant produced. Under Kunwer Sachdev, Su-Kam became the first company in India to develop the Solar Power Conditioning Unit when the industry’s attention was still elsewhere — then protected the technology with patents filed under his leadership.

First Solar PCU in India — then patented, then scaled: Su-Kam designed PWM-based Solar PCUs first, then MPPT-based Solar PCUs as charge-controller technology advanced (see Part 06 — India’s First MPPT). Every installation fed the next revision. Capacity climbed from small single-phase units such as the 1KVA / 24V PCU1K24 in this R&D deck up to 100 kVA three-phase technology — and from 2009 to 2018 Su-Kam exported the highest volume of solar PCUs from India.

Archive video: Su-Kam kept increasing Solar PCU capacity — eventually to 100 kVA three-phase technology.

Su-Kam PCU1K24 tentative look — white front panel, LCD, sinewave Solar PCU
From the R&D deck: tentative look of PCU1K24 — LCD welcome screen, power key, sinewave Solar PCU.

1. What India’s First Solar PCU Had to Be

The 1KVA/24V block diagram is the product definition in miniature. Outside the dashed box: Solar PV Array, Grid/DG supply, Battery Bank, Load, and Remote Monitoring hardware. Inside: Solar Charge Controller (DC-DC), inverter-cum-grid charger, change-over relay, main control unit with RTC, LCD, RS-232 / comm interface, output power monitoring, and a manual rotary bypass.

Su-Kam 1KVA Solar PCU basic block diagram — PV, SCC, inverter, battery, LCD, RS-232, remote monitoring
Basic block diagram: blue callouts mark what an earlier Suntechnics-era supply lacked — RTC, O/P power monitoring, and the communication path for remote monitoring.
General line diagram — Solar PCU as inverter cum solar charge controller with remote monitoring
Line diagram: solar + grid in, battery bank bi-directional, AC distribution to loads, and a remote monitoring device on the PCU.
Su-Kam — first Solar PCU in India under Kunwer Sachdev
Patents filed under his leadership
PWM-based Solar PCU → MPPT-based Solar PCU
Learn from every installation → improve
1KVA class → up to 100 kVA 3-phase
Highest solar PCU exports from India, 2009–2018

2. Solar-First Operation, Indian Mains Reality

Power usage priority was explicit: Solar PV Array / Battery first. Mains was a recovery path. The system switched to mains only after a predefined low battery voltage, stayed on mains until the battery was fully charged (mains plus PV if available), then returned to battery/solar.

  • WW (Wide Window) mode: mains working range 160V to 280V ± 10V
  • NW (Narrow Window) mode: 185V to 265V ± 10V

Those windows are Indian grid engineering: accept ugly voltage when the site needs it, or tighten the window when the load demands cleaner mains — the same worst-case discipline that runs through the Founder Series.

PCU operation — solar/battery priority and WW/NW mains voltage windows
Operation logic: solar/battery priority; WW 160–280V and NW 185–265V mains windows (±10V).
Tentative rear panel — Batt/PV/O/P/I/P MCBs, RS-232, PV and battery terminals
Rear panel intent: separate MCBs for battery, PV, output, and input — plus RS-232 — the field face of a serviceable PCU.

3. From Local Logging to Remote Monitoring — Then to 100 kVA

The old 1KVA/24 BOM was lean: control card, solar charge controller card, LCD, RS-232, software CD + cable. Enough for a technician with a laptop on site. An earlier version supplied to Suntechnics had no onboard data logging; remote monitoring sat outside Su-Kam’s box.

The new BOM changed the product category:

  • Control card + SCC card with onboard data logging
  • LCD, RS-232, software CD + cable
  • GSM card or RS-232 / Ethernet card for remote monitoring

That was one node on a longer curve: keep learning after every installation, keep increasing capacity, and take three-phase Solar PCU technology to 100 kVA — while winning India’s export race in solar PCUs for nearly a decade.

BOM — old 1KVA/24 PCU without onboard data logging
Old BOM: local PC interface only — no onboard log, no GSM/Ethernet line item.
BOM — new 1KVA/24 PCU with onboard data logging and GSM or Ethernet
New BOM: onboard data logging on the control/SCC stack, plus GSM or RS-232/Ethernet for remote reach.
Why that mattered under Kunwer Sachdev: Su-Kam was not content to ship a black box and hope the integrator kept a PC nearby. Logging moved onto the board. Monitoring moved onto the network. Capacity moved from 1KVA-class single-phase to 100 kVA three-phase. The PCU became a plant instrument — and an export product.

4. GUI Parameters: From Live Values to Cumulative kWh

Old GUI (local PC monitoring): PV voltage, PV current, battery voltage, AC output, load % — the live vitals.

New GUI (remote monitoring + data logging): the same vitals plus solar cumulative kWh, and an explicitly different interface for the new version. Energy yield stopped being a guess from a technician’s notebook.

GUI parameters — old PCU local PC monitoring of PV, battery, AC output, load
Old GUI: local PC monitoring of instantaneous electrical parameters.
GUI parameters — new PCU remote monitoring with solar cumulative kWh
New GUI: remote path + cumulative solar kWh — performance you can audit from afar.
Kunwer Sachdev’s Su-Kam · India’s first Solar PCU
PWM → MPPT Solar PCU path
1KVA/24V PCU1K24 · solar-first · WW/NW windows
Onboard data logging + GSM/Ethernet
Scale to 100 kVA 3-phase · export leadership 2009–2018

Conclusion

India’s first Solar PCU was not a late import of a foreign category name. It was engineered at Su-Kam under Kunwer Sachdev when solar was still a niche, protected by patents under his leadership, iterated from PWM to MPPT, hardened by field installations, scaled to 100 kVA three-phase, and shipped abroad in numbers no other Indian maker matched from 2009 to 2018. The 1KVA R&D deck is one clear frame of that longer film — the moment the PCU learned to condition, log, and phone home.

Kunwer Sachdev

Kunwer Sachdev

Founder & MD, Su-Kam Power Systems (1988–2019) and Kunwwer.ai — writing on manufacturing, insolvency, and civilizational memory. Read his story →

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Disclaimer: Kunwer Sachdev exited Su-Kam in 2019 and is not responsible for any activity of the company since. Anyone dealing with Su-Kam does so solely with its current management. Full disclaimer →
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