The Initial Request

The client reached out to Callidus Trade while converting shipping containers at Avon Valley Nursery. Located on a remote site without a mains grid connection, the nursery required a dependable power supply to run day-to-day operations.

The site layout comprises two 40ft shipping containers joined together, alongside a separate toilet block. Power demands on site included:

• Up to 32 LED lights and power for laptops and low-wattage equipment.
• Space heating and cooling: either four electric panel heaters or an air conditioning unit.
• Two electric water heaters and two LED lights in the toilet block.

With no prior experience in solar design, the client initially enquired about combining rooftop and ground-mounted solar panels to top up batteries for day and night use. Callidus Trade stepped in to design an off-grid setup tailored to the site’s actual energy consumption and physical layout.

The Callidus Trade Solution

To deliver consistent off-grid electricity without taking up nursery ground space, Callidus Trade designed a dual-container power system. The complete equipment specification includes:

Solar Array

• 16 x 470W N-type Double Glass Solar Panels: Providing 7.52 kWp of total solar capacity, installed directly on the container roof in an East-West orientation across two strings of eight panels.
• Roof Cabling & Isolation: Single-string DC cables transition on the roof to an 8-metre run of 4-core armoured PV cable, fitted with a 32A 1000V DC isolator for safety.

Power Board & Inverter Infrastructure

• 15kVA Single-Phase Board Build: Built around a Victron MultiPlus-II 48/15000/200-100 inverter-charger installed inside a dedicated plant container.
• Solar Charge Controller: Victron SmartSolar MPPT RS 450/100-MC high-voltage charge controller.
• Underground Interconnection: Connected between containers via 4-core armoured cable routed through a client-dug ground trench.

Battery Storage & Control

• Battery Bank: Two Pytes V16 Lithium-Ion battery modules providing daily power storage.
• System Monitoring: Victron Cerbo GX MK2 monitoring unit paired with a wall-mounted GX Touch 50 display screen for live power tracking on-site.
• DC Distribution & Protection: Two Victron Lynx Distributor 1000A busbars, a Jean Muller Keto-1 fuse switch disconnector with 250A NH fuses, and 400A MEGA fuses.

Why These Technical Decisions Were Made

1. Roof-Mounted East-West Solar Array

Rather than placing panels on the ground where they would take up nursery operational space or risk shading and damage, all 16 solar panels were mounted on the roof of the 40ft container. Orienting the panels East-West in two 8-panel strings smooths solar generation throughout the day, providing a steady power curve from morning to late afternoon that fits typical nursery working hours.

2. Dedicated Plant Container & Armoured Trenching

Power electronics perform best when housed separately from active workspaces. Callidus Trade placed the 15kVA inverter board and battery bank inside a separate spare container. Connecting the rooftop array to the plant room via 4-core armoured cable in an underground trench keeps heat and operational noise out of the nursery space while protecting cabling from site traffic and weather.

3. High-Capacity 15kVA MultiPlus-II Inverter

Running water heaters alongside four panel heaters or an air conditioner demands high continuous power and creates heavy start-up surges. The 15kVA Victron MultiPlus-II provides ample capacity to manage peak loads without tripping, while the high-voltage MPPT RS 450/100 charge controller minimizes cable losses over the run from the panels.

4. Integrated Battery Management & Live Visibility

The Pytes V16 lithium batteries communicate directly with the Victron Cerbo GX system over CAN-bus. This enables intelligent charge management to protect battery health. Meanwhile, the wall-mounted GX Touch 50 touchscreen gives staff clear, real-time visibility of solar generation, battery charge level, and energy consumption.

Summary

The Avon Valley Nursery installation shows how a well-planned off-grid solar and battery system can transform converted shipping containers into a practical, fully powered workplace. By combining rooftop solar generation with Victron power management and Pytes lithium storage, the site operates independently without needing an expensive grid connection.

Need power where the grid doesn’t reach? Get in touch with Callidus Trade to discuss off-grid power solutions for your business.