Multi-Tenant Office Parks Face Electricity Cost Pressure from Every Direction
Office park owners and body corporates face a dual challenge: common-area electricity costs charged to the landlord, and tenant electricity costs that affect tenant satisfaction and lease competitiveness. With Eskom tariff increases year on year, Crestway's operating costs were rising while tenants became increasingly cost-conscious.
Specific considerations:
- Flat commercial roofs required a ballasted mounting solution — no penetrations
- Multi-inverter design needed to handle multiple roof sections with varying orientations
- Tenant submetering and allocation needed to be considered in the design
- Building's structural loading limits required careful engineering
121 kWp Ballasted Grid-Tie — Zero Penetration, Maximum Output
Gentricity designed a 121 kWp system using ballasted racking — ideal for flat commercial roofs:
System specifications:
- 121 kWp solar panel array on ballasted mounting structures
- No roof penetrations — system weighted down, preserving roof integrity and waterproofing warranty
- Grid-tie inverter configuration optimised for the office building's consumption profile
- Generation fed into the building's main distribution board, reducing common and tenant consumption
- Real-time monitoring with tenant-visible production data
Why ballasted mounting:
- Flat commercial roofs cannot always be penetrated without voiding waterproofing warranties
- Ballasted systems are faster to install with less structural interface
- The system can be removed and reinstated if roof maintenance is required
- Load calculations confirmed the roof could support the ballasted racking safely
Results (Estimated based on system specifications and industry benchmarks)
| Metric | Estimated Value |
|---|---|
| Common-area electricity cost reduction | 40–55% |
| Estimated annual savings | R400,000 – R550,000 |
| Tenant electricity cost impact | Reduced through shared consumption offset |
| Payback period | 3–4 years |
| Roof integrity | Maintained — zero penetrations |
Note: Figures are estimates based on system size and SA commercial solar benchmarks. Actual results may vary.
What This Project Demonstrates
For office parks, business parks, and commercial buildings with flat roofs:
- Ballasted mounting resolves the waterproofing penetration concern common on flat roofs
- 121 kWp represents a substantial saving for a mid-size commercial office park
- Solar reduces the building's electricity cost, which can be passed to tenants or retained as margin
- Office buildings operating Monday–Friday during daylight hours are ideal solar candidates
Relevant solutions: