Most solar installers in Nigeria quote a “2-year payback” like it is a fact. It is a sales line. Nobody runs your numbers before they say it.
This guide gives you the actual formula. Use your own fuel price, your own generator habits, your own NEPA bill. The math below never goes stale, because you are the one plugging in today’s numbers.
Want the shortcut? Jump to the worked example or download the free spreadsheet and plug in your own numbers.
The Four-Step ROI Formula
Solar ROI comes down to four numbers. No calculator app required, just a notes app and five minutes.
- Monthly generator + grid cost — what you are spending right now
- Amortised monthly solar cost — your solar system’s cost spread across its lifespan, including battery replacements
- Monthly savings — step 1 minus step 2
- Payback period — system cost divided by monthly savings
That is it. Everything below just fills in these four numbers with your real figures.
Step 1: What You Are Actually Spending Now
Add up three things:
- Generator fuel cost = fuel units per day × today’s price per unit × days per month you run it
- Check today’s pump price before you calculate. NNPC’s site or your local station both work. As of August 2026, petrol ranges from ₦1,270 to ₦1,400 per litre depending on your state and proximity to the Dangote refinery. Diesel runs higher, typically ₦1,400 to ₦1,600 per litre.
- CNG users: Compressed natural gas currently costs roughly ₦200 to ₦300 per kg at conversion stations. A typical 5KVA generator consumes 2–3 kg per hour, so a CNG user running 5 hours daily burns 10–15 kg per day. CNG is far cheaper than liquid fuel, which is good for your wallet now but means solar payback takes longer.
- This is the one number in this whole article that changes daily, so never trust an old figure, including any you saw in a solar sales pitch last month.
- Generator maintenance = monthly average for oil changes, servicing, and repairs
- Be honest here. Most people undercount this by half. Budget at least ₦10,000–₦20,000/month for a 5KVA generator used regularly. CNG generators have lower maintenance costs — no spark plug fouling, cleaner combustion — but still need regular service.
- NEPA/DisCo bill = your actual monthly bill, not the estimated one if you are on a fixed-rate meter that does not reflect real usage
- Note: Your DisCo’s tariff band affects this directly. EKEDC (Lagos), AEDC (Abuja), and Enugu DisCo all operate on different band structures.
Add all three together. That is your true monthly energy cost today.
Step 2: What Solar Actually Costs (Not Just the Sticker Price)
Installers quote system costs. They rarely lead with the number that actually determines your ROI: battery replacement.
Installed system cost — get this from a written quote, not a Jumia listing. Installed cost includes labour, cabling, and site work. Component-only solar prices you see advertised are not what you will pay. If you are not sure how to evaluate quotes, read our solar installer vetting checklist first.
Battery replacement is the hidden cost most quotes skip:
| Battery type | Typical lifespan | Replacements over 15 years | Total 15-year battery cost* | What this means for ROI |
|---|---|---|---|---|
| Lithium (LiFePO4) | 8–10 years | 1–2 | ₦500,000–₦1,000,000 | Highest upfront cost, fewest replacements, best total cost of ownership |
| AGM | 4–5 years | 2–3 | ₦1,000,000–₦1,500,000 | Mid-range cost, frequent replacements, heat-sensitive |
| Flooded lead-acid | 3–4 years | 3–4 | ₦1,200,000–₦1,600,000 | Lowest upfront cost, most frequent replacements, Nigerian heat shortens lifespan further |
*Based on ₦500,000 per AGM replacement; lithium replacements at ₦750,000–₦1,000,000. Prices vary by brand and Naira exchange rate at time of replacement.
Nigerian heat degrades batteries faster than the manufacturer’s rated lifespan assumes. Budget on the shorter end of any range you are quoted. For a deeper dive into which battery actually survives Nigerian heat, see our battery chemistry comparison.
Amortised monthly solar cost = (installed system cost + total battery replacement cost over the system’s lifespan) ÷ (lifespan in months)
This is the number that actually competes against your generator’s monthly cost. Not the upfront price tag.
Step 3 & 4: A Full Worked Example
Here is the formula run end to end. The fuel price below is ₦1,350/litre — the approximate national average as of August 2026. Swap in today’s price and the math does not change.
Inputs:
- Generator: 5 litres/day at ₦1,350/litre, 25 days/month
- Generator maintenance: ₦15,000/month
- NEPA bill: ₦25,000/month
- Installed system cost: ₦3,650,000 (5KVA hybrid)
- Battery: AGM, ₦500,000 replacement, every 5 years
- System lifespan: 15 years
Step 1 — Current monthly cost:
(5 × 1,350 × 25) + 15,000 + 25,000 = 168,750 + 15,000 + 25,000 = ₦208,750/month
Step 2 — Amortised solar cost:
Battery replacements over 15 years at 5-year intervals = 2 replacements
Total solar cost = 3,650,000 + (2 × 500,000) = ₦4,650,000
Amortised monthly = 4,650,000 ÷ (15 × 12) = ₦25,833/month
Step 3 — Monthly savings:
208,750 − 25,833 = ₦182,917/month
Step 4 — Payback period:
3,650,000 ÷ 182,917 = 19.9 months, roughly 1 year 8 months
At today’s fuel prices for this usage pattern, this system pays for itself in under two years. Every month after that is money staying in your pocket instead of going to a fuel station.
Run this exact sequence with your own numbers. If your generator use is lighter or your NEPA supply is more stable, your payback period will be longer, possibly much longer.
CNG User Example
If you run a CNG generator instead, the math changes because your fuel cost is lower:
- CNG consumption: 12 kg/day at ₦250/kg, 25 days/month = ₦75,000/month
- Maintenance: ₦10,000/month (CNG generators need less servicing)
- NEPA bill: ₦25,000/month
- Total current monthly cost: ₦110,000
Using the same ₦3,650,000 solar system with AGM batteries:
Monthly savings: 110,000 − 25,833 = ₦84,167/month
Payback period: 3,650,000 ÷ 84,167 = 43.4 months, roughly 3 years 7 months
Solar still wins over 15 years, but the payback is nearly twice as long. CNG users should consider lithium batteries to reduce replacement costs and shorten payback, or size a smaller system that covers only essential loads.
Download the Free Solar ROI Spreadsheet
Plug in your own numbers and get instant results — works offline, no internet needed. Includes a CNG calculator tab.
Solar vs Generator vs Grid-Only: The Honest Comparison
| Upfront cost | Monthly cost | 5-year total | 10-year total | Best for | |
|---|---|---|---|---|---|
| Solar (5KVA hybrid) | High (₦3.5M–₦4.5M) | Low, mostly fixed | Installed cost + 0–1 battery swap | Installed cost + 1–2 battery swaps | Households running generators most days, especially where fuel + maintenance exceeds ₦100,000/month |
| Generator + NEPA | Low to none | High, fuel-dependent | Fuel + maintenance × 60 months | Fuel + maintenance × 120 months, rises with fuel prices | Areas with decent grid supply (12+ hours/day) and occasional generator backup |
| CNG Generator + NEPA | Low to moderate (conversion kit if needed) | Moderate, CNG price stable | CNG + maintenance × 60 months | CNG + maintenance × 120 months | Households near a CNG station with moderate generator use. Solar payback is longer but still positive over 10+ years |
| Grid-only (no generator) | Lowest | Lowest, but unreliable | NEPA bills only | NEPA bills only, no protection from outages | Locations with genuinely stable 20–24 hour grid supply |
Solar wins on total cost of ownership when generator use is heavy and fuel is expensive. CNG narrows the gap because your running cost is lower. Grid-only wins on upfront simplicity when supply is stable and generator use is minimal. There is no universal winner, only a winner for your specific usage pattern.
Solar ROI in Nigerian Conditions: 3 Real Scenarios
Your payback period depends heavily on where you live and how reliable your DisCo is. Here are three realistic profiles:
Scenario A: Lagos Apartment (EKEDC, Moderate Generator Use)
Scenario B: Abuja Estate (AEDC, Heavy Generator Use)
Scenario C: Northern Nigeria (Low Grid, Diesel Generator)
Scenario D: Lagos Household with CNG Generator
Note: These are estimates. Run the 4-step formula above with your exact numbers before making a decision.
What Happens to Your ROI When Fuel Prices Jump
Your payback period is not fixed. Every time petrol, diesel, or CNG rises, your generator cost rises with it — but your amortised solar cost stays exactly where it was the day you installed. This is why solar becomes a better investment over time, not a worse one.
If you calculated your payback at ₦1,350/litre and petrol moves to ₦1,600/litre, rerun Step 1 with the new figure. Your monthly savings increase, and your payback period shrinks. The formula above never goes stale because you update it with today’s price, not last year’s.
Rule of thumb: A ₦200 increase per litre typically shortens payback by 3–6 months for households burning 5+ litres daily. CNG prices have been more stable, but any CNG price increase works the same way — your payback shortens.
Financing Solar in Nigeria: Beyond the Upfront Cash Payment
Most Nigerians do not have ₦3.5 million sitting in a savings account. Here are the real financing options that change your ROI maths:
Pay-As-You-Go (PAYG) Solar
Companies like Lumos and Daystar offer solar systems on a monthly subscription model. You pay a setup fee (₦50,000–₦150,000) then monthly fees (₦15,000–₦30,000) for 3–5 years. At the end, you own the system.
Best for: Renters, first-time solar users, or households with monthly energy costs below ₦50,000
Bank Solar Loans
Several Nigerian banks now offer solar-specific loans:
- Sterling Bank: Solar financing at competitive rates for homes and SMEs
- Union Bank: Green energy loans with extended tenures
- BoI (Bank of Industry): Solar loans for manufacturers and businesses
Best for: Homeowners with steady income who want a full-sized system
Rent-to-Own (Installer Financing)
Some installers offer in-house financing where you pay 30–50% upfront and spread the balance over 12–24 months.
Best for: Buyers who trust their installer and want quick deployment
How financing changes your ROI:
If you take a bank loan at 20% interest on a ₦3.5M system, your total repayment might be ₦4.2M over 3 years. Add that to your battery replacement costs, then run the amortised monthly formula. Financing can push a 3-year payback to 5+ years — still often better than generator costs, but the margin is thinner.
Solar ROI for Small Businesses in Nigeria
The same four-step formula applies to shops, cold rooms, and small offices — but the numbers scale differently. A business running a 10KVA diesel generator 12 hours a day at ₦1,400/litre can see payback in under 18 months, not 3–5 years. The higher your current energy cost, the faster solar pays for itself.
If you run a business, factor in:
- Diesel vs petrol vs CNG: Diesel generators are more efficient per kWh but diesel prices track differently from petrol. CNG is cheapest but requires conversion kit investment. Use your actual fuel type in Step 1.
- Revenue protection: Unlike a home, every hour of power outage can mean lost sales. Solar’s value includes revenue you did not lose, not just fuel you did not buy.
- Tax treatment: Some business solar installations qualify for capital allowances. Speak to your accountant before finalising your ROI numbers.
Why Your Payback Might Be Longer Than an Installer Promised
Three things installers routinely leave out of their pitch:
Currency exposure on imported parts. Inverters and batteries are priced against dollar-equivalent costs. If the naira weakens before your battery replacement is due, that replacement costs more than your original quote assumed.
Optimistic generator-hour assumptions. Some installers calculate your “savings” against a generator running 24/7, when your real usage might be 8–10 hours a day. This inflates the promised payback period.
Oversized systems. A bigger system means a bigger loan or bigger upfront cost, which pushes your payback period out, even if it “future-proofs” you for appliances you do not currently run.
None of these make solar a bad investment. They make a sales-pitch payback number unreliable. Your own calculation, using your own habits, is the only number worth trusting.
Who Should Skip Solar Right Now
If your generator use is already light — say once or twice a week — and your NEPA supply is genuinely stable, your current monthly energy cost may already sit below what an amortised solar system would cost you. Run the four-step formula above before you commit. If step 3 comes out negative or close to zero, solar is not the right move yet.
CNG users with moderate generator use and decent grid supply should be particularly careful. Your running cost is already low. Solar may still make sense over 15 years, but the payback is longer and the monthly savings are thinner. Run the numbers with your actual CNG consumption before committing.
A portable power station may serve you better for occasional outages or lighter loads such as routers, laptops, and fans, without the installation cost or the battery-replacement math. It will not run a fridge or an AC unit, so it is not a substitute for a full system if your loads are heavy.
Our Verdict
Solar makes clear financial sense in Nigeria when generator use is frequent and fuel costs are the bulk of your current energy spend. It makes less sense when NEPA supply is already reliable and generator use is occasional. CNG users see a longer payback but still benefit over the full system lifetime. The formula above tells you which category you are in, using your own numbers, not an installer’s assumptions.
Best for: households and small businesses running a generator most days, especially where fuel + maintenance costs already exceed ₦100,000/month. CNG users should verify payback exceeds 5 years before committing.
Skip or wait if: your generator use is occasional and your NEPA bill is your main energy cost already, or if you are a CNG user with payback stretching beyond 8 years.
Get Your Numbers Right Before You Buy
Use the calculator above, then request itemised quotes from at least three installers. Our installer vetting checklist shows you exactly what to ask for before you hand over a deposit.
Download the Free Vetting Checklist →
Want the full deep dive? Power Without the Panic covers system sizing, brand reviews, and the complete installer red-flag checklist.
FAQ
What is a good solar payback period in Nigeria?
Anywhere from 2 to 5 years is generally considered strong for petrol and diesel users. CNG users typically see 5 to 8 years. Anything beyond 8 to 10 years starts to compete with the system’s own lifespan, which weakens the case for solar.
Does solar ROI change with fuel price increases?
Yes, and usually in solar’s favour. Every fuel price increase shortens your payback period further, since your generator cost rises while your amortised solar cost stays fixed. This is why the formula in this guide uses today’s price rather than a fixed one.
How much does battery replacement affect solar ROI?
Significantly. Battery replacement is often the single largest cost that most buyers don’t account for upfront. An AGM battery costing ₦500,000 and needing replacement twice over a 15-year system adds ₦1,000,000 to total cost of ownership, money a sticker-price comparison never shows.
Is solar worth it if I have stable NEPA supply?
Not always. If your generator use is already light, your current monthly energy cost may be lower than the amortised cost of a full solar system. Run the four-step formula in this guide before assuming solar is the right move.
What is the difference between solar payback period and solar ROI?
Payback period is how long until the system pays for itself. ROI is the ongoing return after that point, meaning the savings that continue every month once the system has already paid off its own cost.
Can I calculate solar ROI without an installer’s quote?
You can estimate it using rough per-KVA cost ranges, but a real quote gives you the installed cost, which is what actually determines your amortised monthly figure. Estimate first to see if it is worth pursuing quotes, then confirm with real numbers.
Does system lifespan matter more than upfront cost?
Both matter, but lifespan determines how many battery replacements you’ll pay for. A 15-year system needing two AGM battery swaps at ₦500,000 each often has a bigger impact on total cost of ownership than a few hundred thousand naira difference in the initial system price.
Can I finance a solar system in Nigeria?
Yes. Options include PAYG subscriptions (Lumos, Daystar), bank solar loans (Sterling, Union Bank, BoI), and installer rent-to-own plans. Each changes your ROI maths — factor interest or subscription costs into your amortised monthly calculation.
I use CNG for my generator. Does solar still make sense?
CNG is significantly cheaper than petrol or diesel, so your current monthly energy cost is lower. This means your solar payback period will be longer — often 5 to 8 years instead of 2 to 4. Run the formula with your actual CNG price per kg to see if solar still beats your generator cost over the system’s lifetime. Over 15 years, it usually still does, but the margin is thinner.