Solar vs Diesel in The Bahamas
The real 20-year cost of a generator, set against solar and battery storage.
A generator never pays you back. Every year it demands fuel, maintenance and eventually a full replacement. Solar pays for itself in under two and a half years, then puts money back in your pocket.
20kW Diesel Generator
Typical standby genset, installed in The Bahamas
13kW Solar + 20.5kWh Battery
22-panel system, fully installed by My Energy
20-Year Cumulative Cost and Savings
Two generator scenarios: Out Islands (360 hrs/yr, reflecting frequent outages) and New Providence (150 hrs/yr, a more reliable grid). Both include full unit replacement at year 12 and averaged maintenance. Solar includes $100/yr maintenance throughout, and its savings are valued at the marginal grid rate of $0.39/kWh, which is what each self-generated unit actually displaces above 800 kWh a month.
Where Every Dollar Goes Over 20 Years
Generator figures use the Out Islands scenario. New Providence fuel costs are lower, around -$41,000 over 20 years, but the pattern is the same: relentless outflow.
| Cost item | Amount |
|---|---|
| Initial purchase + install | -$22,000 |
| Diesel fuel (360 hrs/yr x 20 yrs) | -$70,560 |
| Maintenance (~$900/yr x 20 yrs) | -$18,000 |
| Replacement unit at Year 12 | -$22,000 |
| 20-Year Total | -$132,560 |
| Cost item | Amount |
|---|---|
| System fully installed | $16,733 |
| Maintenance ($100/yr x 20 yrs) | $2,000 |
| Fuel cost (20 years) | $0 |
| Replacement needed | No |
| 20-Year Total | $18,733 |
Realistic Maintenance Schedule
Generator maintenance is not the same every year. Early years are lighter, later years demand more. Here is the honest breakdown by lifecycle phase.
| Lifecycle phase | Annual cost |
|---|---|
| Years 1-3, new systemOil changes, basic filters, inspection | ~$400/yr |
| Years 4-8, moderate wearPlus coolant, belts, hoses, fuel filter, battery | ~$900/yr |
| Years 9-12, aging systemPlus injectors, valves, tank overhaul, electrical | ~$1,500/yr |
| Years 13-20, after replacementCycle repeats from the Year 1 phase | ~$400-900/yr |
| Blended Average | ~$900/yr |
| Maintenance item | Annual cost |
|---|---|
| Panel cleaning, optionalRain handles most of it in The Bahamas | $100/yr |
| Oil changes | None ever |
| Filters, coolant, belts | None ever |
| Fuel | $0 forever |
| Moving parts | Zero |
| Noise, fumes, vibration | Zero |
| Every Year, Same Cost | $100/yr |
Warranty and Lifespan
| Typical manufacturer warranty | 2-5 years |
|---|---|
| Realistic coastal lifespan | 10-12 years |
| Replacement cost | -$22,000 |
| Panel performance warranty | 30 years |
|---|---|
| Inverter warranty | 10-15 years |
| Battery warranty | 10-15 years |
| Moving parts that can fail | None |
Assumptions. Bahamas diesel at $7.00/gallon (June 2026). 20kW generator at 75% load burning 1.4 gal/hr. Out Islands runtime 360 hrs/year, based on frequent extended outages on the Family Islands. New Providence runtime 150 hrs/year. Maintenance averaged at $900/year based on phased lifecycle costs with Bahamas parts and labour pricing. Generator replacement at year 12 based on 10,000+ operating hours in a coastal salt-air environment. Solar savings are valued at the marginal grid rate of $0.39/kWh, being the published residential tariff above 800 kWh a month ($0.1495 energy plus $0.2140 fuel, plus 10% VAT), which is the rate each self-generated unit actually displaces. Households below that threshold pay less per unit and will save proportionately less. Solar production 19,012 kWh/year. Panel warranty 30 years, inverter and battery warranty 10-15 years. Diesel price assumed constant, which historically trends upward and therefore makes the generator figures conservative. All figures BSD/USD at the 1:1 peg.
Solar vs diesel: common questions
Is solar cheaper than a generator in The Bahamas?
Yes, and the gap is large. Over 20 years a 20kW standby diesel generator costs roughly $132,560 in the Out Islands once fuel, maintenance and a year-12 replacement are counted. A 13kW solar system with 20.5 kWh of battery storage costs about $18,733 in total, and avoids roughly $148,000 of grid charges along the way. That is a net position of about $129,561 in your favour.
How long before a solar system pays for itself?
Around 2.3 years for the system modelled here, valuing the power it generates at the marginal grid rate of $0.39/kWh. After that point the system has returned its full cost and every year of generation afterwards is money kept rather than money spent.
Why do generators need replacing after 12 years?
Caribbean coastal conditions are hard on machinery. Salt air, humidity and sand corrode enclosures, degrade fuel lines and destroy control electronics. Most gensets reach the end of practical life somewhere between year 10 and year 12, which means a second purchase of about $22,000 inside a 20-year window.
What maintenance does a solar and battery system need?
Very little. Budget roughly $100 a year for optional panel cleaning, though rainfall handles most of it here. There are no oil changes, filters, coolant, belts or fuel. There are no moving parts to wear out.
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