For tower companies, power is the largest operating cost on most off-grid or weak-grid sites. Solar-hybrid systems are now common, but the decision should be based on a calculation, not a brochure. Here is the method we use.
Step 1: Establish the true cost of diesel
The cost of diesel power is more than the pump price. For each site, add up:
- Fuel: litres per month × delivered price per litre (including haulage)
- Losses: pilferage and reconciliation gaps — often significant on remote sites
- Maintenance: servicing every few hundred run-hours, plus overhauls
- Replacement: generator life shortened by long daily run-hours
Divide the monthly total by the energy delivered (kWh) to get your cost per kWh. This number is the benchmark everything else must beat.
Step 2: Model the alternatives
Compare three scenarios over 10 years:
- Diesel only — today's cost, escalated for fuel price changes.
- Grid + diesel — grid supply for available hours, generator for the rest. Requires a grid connection (see our grid connection guide).
- Solar-hybrid — PV and batteries carry most of the load; the generator (and grid, if present) fill gaps.
Step 3: A worked example (illustrative numbers)
The figures below are illustrative only — replace them with your own site data.
- Site load: 3 kW continuous ≈ 72 kWh/day
- Diesel-only cost: if the all-in cost is equivalent to $0.60/kWh → about $43/day, or roughly $15,800/year
- Solar-hybrid design covers 70% of energy; the generator covers 30% → diesel cost falls to about $4,700/year, plus maintenance on the solar system
- If the hybrid system costs $35,000 installed and saves around $10,000/year after maintenance, simple payback is about 3.5 years
Battery replacement during the system's life must be included, and grid availability changes the result substantially: a site with good grid hours may get a faster payback from a grid connection alone.
Step 4: Check the non-financial factors
- Uptime: fewer generator failures means fewer outages and SLA penalties.
- Security: less fuel on site means less theft risk.
- Emissions reporting: increasingly required by international investors and tower-company shareholders.
The practical answer
On many sites the best result is not one technology but a sequence: connect to the grid where a feeder is available, add solar and storage to cover grid gaps, and keep the generator as last-resort backup. We model all three for you from your site data. Request a site assessment.
