Solar Panel ROI in Indonesia: Real Payback Math 2026

"When does it pay back?" is the first question 9 out of 10 Indonesian homeowners ask about solar. But if your only goal is payback, you're probably reading the decision wrong. Solar is an independence investment first and a financial investment second. What you're buying is a home that's resistant to PLN tariff swings and grid hiccups for the next 25 years. The payback math happens to work out too, and this article gives you real numbers with transparent assumptions so you can weigh both sides for the residential market here.

This goes much deeper than "payback in 7 years." We cover 25-year ROI math, NPV and IRR calculations, worked examples per PLN tier, ROI variation by city, eight variables that move the number, battery vs no-battery comparison, PLN tariff sensitivity analysis, and five scenarios where ROI can go negative. Lots of numbers, all with open assumptions. If you want to check the numbers for your specific home first, use the solar panel calculator before reading further.

Reading this in Bahasa Indonesia? Switch to the Indonesian version.

TL;DR

• Average financial payback in Indonesia, 2026: 5 to 9 years, depending on profile.
• Short (4 to 6 years): high-irradiance city + large PLN bill (Surabaya, Bali, South Jakarta with bills above Rp 2 million).
• Moderate (6 to 8 years): average city + moderate bill.
• Long (8 to 12 years): low-irradiance city (Bandung, Yogyakarta) with bills under Rp 1 million, or low self-consumption.
• After payback: panels keep working for 15 to 17 more years. Net lifetime production is 2 to 3x the initial investment, plus your home is no longer 100% dependent on PLN throughout that time.
• Effective IRR: 12 to 18%, well above bank deposits and conservative fixed income.

The basic payback formula

Payback (years) = Investment / Annual savings
Annual savings = kWp x Monthly output per kWp x 12 x Offset rate x PLN tariff per kWh

Variables:

• kWp: system size (kilowatt-peak of installed panels)
• Monthly output per kWp: 90 to 130 kWh, depending on city irradiance
• Offset rate: % of household usage met by panels, 40 to 80% depending on usage pattern
• PLN tariff per kWh: R-1 small connection Rp 1,444; R-1 large connection Rp 1,699

Worked examples per profile

Profile A: Single-family home, 2200 VA, Surabaya, Rp 1.2 million/month bill

• 2.5 kWp system
• Output: 2.5 x 120 kWh x 12 = 3,600 kWh/year
• Offset 60% (moderate use, nighttime-dominant)
• Savings: 3,600 x 0.6 x 1,444 = Rp 3.12 million/year
• Investment: Rp 40 million
• Payback: 12.8 years (pessimistic)

Hold on, isn't payback usually 5 to 7 years? It is, when:

• Offset hits 75% (daytime-dominant: WFH plus daytime AC). Savings rise to Rp 3.9 million/year, payback drops to 10 years.
• PLN tariff escalates 5% per year on average. Present-value-adjusted payback drops to about 8 years.
• Panel productivity exceeds 120 kWh/kWp/month (good irradiance). Payback drops to 7 to 8 years.

The "5 to 7 years" payback most installers market assumes the best case. Realistic moderate cases run 7 to 10 years for this profile.

Profile B: Single-family home, 5500 VA, South Jakarta, Rp 2.8 million/month bill

• 5 kWp system
• Output: 5 x 115 kWh x 12 = 6,900 kWh/year
• Offset 70% (daytime AC plus dual WFH)
• R-1 non-subsidized tariff Rp 1,699
• Savings: 6,900 x 0.7 x 1,699 = Rp 8.2 million/year
• Investment: Rp 70 million
• Payback: 8.5 years (conservative)

With 5%/year tariff escalation, present-value payback drops to about 7 years.

Profile C: 7.5 kWp Bali villa, Rp 3.5 million/month bill

• Output: 7.5 x 130 kWh x 12 = 11,700 kWh/year (Bali irradiance is high)
• Offset 80% (consistent hospitality use)
• Savings: 11,700 x 0.8 x 1,699 = Rp 15.9 million/year
• Investment: Rp 110 million
• Payback: 7 years

Short-term-rental Bali villas (Airbnb, Booking.com) often see even shorter payback because offset can hit 85%.

25-year ROI math: payback is just one point on a 25-year curve

Most solar discussions in Indonesia stop at payback, which is the point where your initial investment is recovered. This is not the right way to evaluate a 25-year asset. Payback is one data point. The full 25-year ROI curve tells a much more interesting story.

Simple payback vs NPV vs IRR: three different numbers

Simple Payback is the easiest to calculate and the most commonly quoted. The formula is: investment divided by year-one annual savings. The problem is that simple payback ignores the time value of money, ignores PLN tariff escalation, and ignores replacement costs for inverters or batteries along the way.

NPV (Net Present Value) is more rigorous. NPV calculates the present value of all future cash flows (savings minus costs) minus the initial investment. A positive NPV means the investment is worthwhile. A negative NPV means it doesn't meet your required return. NPV uses a discount rate (typically 8 to 10% for Indonesian household investment decisions) to convert future rupiah into today's rupiah.

IRR (Internal Rate of Return) is the discount rate that makes NPV equal to zero. In plain language, IRR is the "effective interest rate" your solar investment generates. If IRR exceeds the return on a bank deposit or mutual fund you're comparing against, solar is mathematically the better choice.

Why ROI does not equal payback

Suppose you invest Rp 40 million in a 2.5 kWp system in Surabaya. Simple payback is 8 years (using moderate assumptions with 5% PLN escalation). But the 25-year ROI is far larger.

After payback in year 8, you still have 17 years of useful panel life running at zero incremental cost. Annual savings in year 8 are not still Rp 3.9 million (year-one figure) because PLN tariffs have been escalating for 8 years. At 5% annual escalation, the effective tariff by year 8 is already 1.48x the 2026 baseline, meaning annual savings have grown to around Rp 5.8 million.

By year 15, PLN tariffs are roughly double the 2026 level, and annual savings from that same 2.5 kWp system approach Rp 8 million. By year 25, savings exceed Rp 13 million per year, from a system you bought for Rp 40 million.

Sample 25-year run: Rp 40 million capex, 8-year payback, 17 years of free production after

Assumptions: 2.5 kWp system, Surabaya, 70% offset, 5% annual PLN escalation, 0.5% annual panel degradation, Rp 1 million/year maintenance, inverter replacement Rp 8 million at year 12.

Year	Annual Savings (Rp)	Cost Events	Cumulative Net (Rp)
1	3,900,000		-36,100,000
3	4,306,000		-27,300,000
5	4,757,000		-16,900,000
8 (payback)	5,767,000		+2,100,000
10	6,376,000		+14,800,000
12	7,049,000	Inverter -Rp 8M	+22,600,000
15	8,231,000		+45,700,000
20	10,506,000		+99,100,000
25	13,402,000		+164,300,000

Total net return over 25 years: roughly Rp 164 million from a Rp 40 million initial investment. That is 4.1x the initial outlay, or an effective IRR of around 14%. These are not marketing numbers. This is a conservative calculation with fully transparent assumptions that already accounts for panel degradation, annual maintenance, and inverter replacement.

For a larger system (5 kWp, Rp 75 million investment), the scale of savings is proportionally larger. 25-year net return can reach Rp 250 to 350 million depending on usage profile and city.

Bank deposit at 5% vs solar IRR 12 to 18%

This is a question we hear regularly. If you have Rp 40 million, is it better in a bank deposit or on your roof?

Bank deposit at 5% per year for 25 years:

• Initial capital: Rp 40 million
• After 25 years (compound): Rp 40 million x (1.05)^25 = Rp 135.5 million
• Gain: Rp 95.5 million

Solar panels (effective IRR 14%, conservative):

• Initial investment: Rp 40 million
• Net return over 25 years: Rp 164 million (from the table above)
• Gain: Rp 164 million in savings avoided

One caveat worth noting: bank deposits generate new cash, while solar generates savings (economically equivalent but different in terms of liquidity and tax treatment). Deposits are more liquid. You can withdraw any time. Solar is a fixed asset tied to a property. If you need liquidity, deposits win. If you own a home you plan to occupy for 10 or more years, solar is mathematically more profitable.

One more factor that favors solar: PLN tariffs will likely keep rising. If tariffs climb 7% per year (not 5%), solar IRR rises to 17 to 19%. The deposit remains at 5%. The gap widens every time PLN raises rates more aggressively.

Use the solar panel calculator to input your actual bill and location, then compare the resulting payback and estimated savings against what your current savings account or deposit earns.

ROI per PLN connection tier (1300/2200/3500/5500 VA)

Your PLN bill is the single most important input in the ROI calculation. Higher bill means higher potential savings, which means faster payback. Here are worked examples for the most common PLN residential tiers in Indonesia.

Shared assumptions across all examples

• Location: South Jakarta (PSH 4.8 hours/day, moderate)
• Offset rate: 65% (mix of WFH daytime plus evening usage)
• R-1 non-subsidized tariff: Rp 1,699/kWh (2026 rate)
• System price: Rp 17 million per kWp (on-grid, mid-tier)
• PLN tariff escalation: 5% per year (conservative assumption)
• Panel degradation: 0.5% per year (tier-1)
• Maintenance: Rp 1 million/year, inverter replacement Rp 10 million at year 12

PLN Tier	Monthly Bill	System (kWp)	Capex	Year-1 Savings	Simple Payback	Payback (5% escalation)	25-Year Net
1300 VA	Rp 500,000	1.5 kWp	Rp 25.5M	Rp 2.0M	12.8 yrs	9.5 yrs	Rp 65M
2200 VA	Rp 1,200,000	2.5 kWp	Rp 42.5M	Rp 4.8M	8.9 yrs	7.0 yrs	Rp 130M
3500 VA	Rp 2,000,000	4 kWp	Rp 68M	Rp 7.6M	9.0 yrs	7.2 yrs	Rp 210M
5500 VA	Rp 3,200,000	6 kWp	Rp 102M	Rp 12.1M	8.4 yrs	6.8 yrs	Rp 335M

Detail by tier

1300 VA (Rp 500,000/month): This is the thinnest profile. At 9.5-year payback with escalation, the investment is technically positive but with a narrow safety margin. If your usage pattern is night-dominant or there's any roof shading, payback can stretch to 12 or more years. For bills under Rp 600,000, solar rarely makes sense as a pure financial decision, though the energy independence argument still stands. See the "When ROI goes negative" section below.

2200 VA (Rp 1,200,000/month): The entry-level sweet spot. Payback at 7 years with escalation is reasonable for a 25-year commitment. Net 25-year return of Rp 130 million from a Rp 42.5 million investment is 3x. This is the most common profile in our database, and the ROI is solid when daytime usage exists (WFH, daytime AC, morning laundry).

3500 VA (Rp 2,000,000/month): ROI becomes compelling. A Rp 2 million monthly bill with a 4 kWp system generates Rp 7.6 million in year-one savings. Payback at 7.2 years, 25-year net Rp 210 million. For families with 2 or 3 ACs running during the day, the offset rate can exceed the 65% assumption above, shortening payback further.

5500 VA (Rp 3,200,000/month): The ROI case here is clearest. Large bills mean large savings potential. Net 25-year return of Rp 335 million from a Rp 102 million investment is 3.3x. Payback at 6.8 years in the moderate profile. With daytime-dominant usage (domestic staff, WFH, pool pump), payback can reach 5.5 to 6 years.

Note: the table above uses South Jakarta assumptions. Different cities with different irradiance produce different numbers. Jump to the "ROI by city" section to see how irradiance changes these figures.

For detailed capex breakdown per tier, solar panel cost in Indonesia 2026 covers the component-by-component pricing in depth.

ROI by city: why Bali beats Banjarmasin on payback speed

Solar irradiance (PSH, Peak Sun Hours) is one of the biggest determinants of how much electricity your panels produce per day. Indonesia has significant PSH variation from west to east, and this directly affects ROI.

What PSH is and why it matters for ROI

PSH is the number of equivalent hours per day when solar irradiance is at 1,000 W/m2 (the standard test condition panels are rated against). A 1 kWp panel in a city with PSH 5.0 produces 5.0 kWh per day. A city with PSH 4.0 produces 4.0 kWh per day from the same panel. A difference of 1 PSH equals 20% more annual electricity production, which directly translates into a proportionally larger annual savings figure and a faster payback.

ROI by city: 5 kWp system, Rp 2.5 million/month bill

Assumptions: 5 kWp on-grid system, Rp 85 million capex, 70% offset, Rp 1,699/kWh tariff, Rp 1 million/year maintenance, 5% annual PLN escalation.

City	PSH (hours/day)	Annual Output (kWh)	Year-1 Savings (Rp)	Payback	25-Year Net (Rp)
Kupang, NTT	5.6	10,220	12.2M	7.0 yrs	330M
Denpasar, Bali	5.2	9,490	11.3M	7.5 yrs	305M
Surabaya	5.0	9,125	10.9M	7.8 yrs	292M
South Jakarta	4.8	8,760	10.4M	8.2 yrs	278M
Semarang	4.7	8,578	10.2M	8.3 yrs	271M
Medan	4.5	8,213	9.8M	8.7 yrs	257M
Pontianak	4.4	8,030	9.6M	8.9 yrs	250M
Banjarmasin	4.3	7,848	9.4M	9.1 yrs	243M
Bandung	4.2	7,665	9.1M	9.3 yrs	236M
Yogyakarta	4.2	7,665	9.1M	9.3 yrs	236M

Why Bali beats Banjarmasin

The PSH gap between Bali (5.2) and Banjarmasin (4.3) is 0.9 hours per day. For a 5 kWp system, that's 1,642 additional kWh per year. At Rp 1,699 with 70% offset, the annual savings difference is around Rp 1.95 million per year. Over 25 years, cumulative gap exceeds Rp 65 to 70 million. Payback is also 1.5 to 2 years faster.

Banjarmasin is not a bad choice for solar, but expectations need calibration. Cities in central and east Kalimantan have lower PSH than Bali and NTT due to higher cloud cover. Solar is still financially viable, but payback is longer and 25-year net return is lower.

Cities in NTT like Kupang, Labuan Bajo, and Bima actually have some of the best solar irradiance in Indonesia (PSH 5.3 to 5.8 hours/day), making solar ROI there potentially very attractive when installation infrastructure is available. For detailed city-specific context, see the solar panel in Banjarmasin and solar panel in Kupang articles.

Eight variables that affect your solar ROI

Payback and ROI are not single numbers. Eight variables can each shift the final figure significantly. Understanding these eight matters more than memorizing an average payback number, because your home's profile may differ substantially from the "average home."

Variable 1: PLN tariff escalation at 5% per year (compounding effect)

This is the factor most commonly ignored in simple calculations. PLN Indonesia residential tariffs have historically risen 3 to 7% per year, averaging around 5%. The compounding effect over 25 years is substantial.

If PLN tariff starts at Rp 1,699/kWh today and rises 5% per year:

• Year 5: Rp 2,168/kWh
• Year 10: Rp 2,767/kWh
• Year 15: Rp 3,531/kWh
• Year 20: Rp 4,507/kWh
• Year 25: Rp 5,750/kWh

Your solar system produces the same kWh (minus degradation), but each kWh you save is worth more every year. This is a built-in inflation hedge that a bank deposit does not offer.

Variable 2: Local irradiance (PSH)

Covered in the city section above. PSH varies from 4.0 to 5.8 across Indonesia. Enter your specific city in the solar panel calculator for accurate output figures.

Variable 3: Cover percentage (full backup vs 50% vs daytime-only)

How much of your PLN bill solar can displace depends heavily on your usage pattern.

• Daytime-dominant (WFH, daytime AC, morning laundry): offset rate 70 to 80%. Faster payback.
• Mixed (daytime AC plus moderate evening use): offset rate 55 to 70%. Moderate payback.
• Night-dominant (everyone out during the day, main usage in the evening): offset rate 30 to 50%. Longer payback. Solar may not be optimal without a battery.

If your profile is night-dominant, a hybrid system with battery is worth considering, even at higher upfront cost. The LiFePO4 vs lead-acid battery comparison covers battery technology relevant to the Indonesian climate.

Variable 4: Panel brand and degradation rate

Tier-1 panels (Jinko Tiger Neo, LONGi Hi-MO 6, Canadian Solar) have guaranteed degradation rates of 0.45 to 0.55% per year, with 25-year power warranties (minimum output 80 to 87% at year 25). Tier-2 or unknown brands often degrade at 0.6 to 0.8% per year with weaker warranty support.

The difference between 0.5% and 0.7% degradation looks small, but over 25 years it means you receive 87.5% of original output versus 83.5%. On a 5 kWp system, that's roughly 175 kWh per year of lost production at end of life. More critically, fast-degrading panels can lose 20 or more percent of output by year 15, well before warranty claims can be easily processed. The solar panel tier-1 vs tier-2 guide covers brand selection in detail.

Variable 5: Inverter efficiency loss over time

A new inverter operates at 96 to 98% efficiency. After 5 to 7 years, efficiency can drop to 93 to 95% as electronic components age. A 3 to 4% efficiency loss means proportionally less production, even if panels are still generating at full output. The article on inverters: Deye vs Growatt vs Luxpower covers which brands maintain efficiency better over time.

Variable 6: Battery cycle life (LFP 6,000 cycles vs lead-acid 800 cycles)

If you install a hybrid system with a battery, battery lifespan directly affects total cost of ownership and ROI. LFP (LiFePO4) has a cycle life of 6,000 to 8,000 cycles, meaning in Indonesia (roughly one full cycle per day) the battery lasts 16 to 22 years before it needs replacing. Lead-acid lasts 800 to 1,200 cycles, which translates to replacement every 2 to 3 years. The cost difference over 25 years between replacing lead-acid 3 to 4 times versus LFP once is enormous. See LiFePO4 vs lead-acid for Bali villa for the full financial comparison.

Variable 7: Maintenance cost (Rp 500,000 to 2 million per year)

Solar maintenance is not zero. Panel cleaning 1 to 2 times per year (Rp 200,000 to 500,000 per visit), annual inspection (Rp 200,000 to 500,000), and minor repairs if needed. Realistic total: Rp 700,000 to 2 million per year depending on system size and location. Include this in your ROI calculation; do not assume zero maintenance.

Variable 8: Tariff escalation rate assumption (sensitivity analysis)

The assumed PLN tariff escalation rate directly changes both payback and 25-year net return. Summary table:

PLN Escalation Assumption	Payback (2.5 kWp, 65% offset)	25-Year Net	Effective IRR
0% (flat)	11.0 years	Rp 62M	10.5%
3% per year	9.5 years	Rp 98M	12.5%
5% per year	8.2 years	Rp 130M	14.0%
7% per year	7.1 years	Rp 178M	16.5%

Even with completely flat PLN tariffs for 25 years (a very conservative assumption that has never happened historically), solar ROI is still 10.5% IRR. Bank deposits cannot offer 10.5% in any current conditions.

ROI with battery vs without battery

The "battery or no battery" question is one we get often. The answer depends on your primary motivation and usage profile.

On-grid (no battery): pure financial ROI

On-grid is the most cost-efficient option in pure financial terms. No battery means lower capex and faster payback on paper.

Worked example: 5 kWp on-grid in Surabaya, capex Rp 85 million.

• Annual output: 5 x 120 x 12 = 7,200 kWh
• Offset 65%: savings of 4,680 kWh x Rp 1,699 = Rp 7.95 million/year
• Payback: 85 / 7.95 = 10.7 years (flat), 8.7 years (5% escalation)
• 25-year net: approximately Rp 170 to 195 million

Limitation of on-grid: when PLN has an outage, your panels shut off too (safety anti-islanding regulation). No backup power. And if you produce more than you consume during the day (surplus), that surplus goes into PLN's grid and earns credit at roughly 65% of the retail tariff via net metering, not 100%.

Hybrid (with LFP battery): comprehensive ROI

A hybrid system adds a battery to store daytime surplus for evening use. This increases offset rate significantly for night-dominant usage profiles, and provides backup during PLN outages.

Worked example: 5 kWp + 5 kWh LFP battery, capex Rp 130 million (Rp 85M solar + Rp 45M battery).

• Annual output: 7,200 kWh
• Offset rises to 80% because daytime surplus is stored: savings of 5,760 kWh x Rp 1,699 = Rp 9.78 million/year
• Payback: 130 / 9.78 = 13.3 years (flat), 10.5 years (5% escalation)
• Battery replacement at year 15 (LFP 6,000 cycles): subtract Rp 40 to 50 million
• 25-year net: approximately Rp 155 to 180 million (after battery replacement)

On pure financial ROI, on-grid wins. But hybrid delivers value that's hard to price in monthly bill savings: backup power during outages, higher independence from PLN, and genuine evening electricity from stored solar energy. If you live in a city with frequent outages (outside Java, parts of Central Java, NTT), backup power is very real value.

Side-by-side comparison

Metric	On-Grid (5 kWp)	Hybrid (5 kWp + 5 kWh LFP)
Capex	Rp 85 million	Rp 130 million
Offset rate	65%	80%
Year-1 savings	Rp 7.95 million	Rp 9.78 million
Payback (5% escalation)	8.7 years	10.5 years
25-year net	Rp 195 million	Rp 165 million
Backup during PLN outage	No	Yes
Best for	Large bills, daytime-dominant	Night-dominant or frequent outages

Battery replacement at year 15 does eat into returns, but LFP's cycle life means one replacement in 25 years is the realistic scenario, not the 2 to 3 times required for lead-acid. If battery prices continue their downward trend (down roughly 60% from 2020 to 2026), the year-15 replacement will likely cost less than current estimates suggest.

ROI vs alternative investments (deposits, mutual funds, stocks, property)

You need context, not just solar numbers in isolation. How does solar ROI compare to other uses of the same capital?

Bank deposits

Indonesian national bank deposits currently offer 4.5 to 6% per year, with 5% being a reasonable planning figure for 25 years. Deposits compound: Rp 85 million at 5% for 25 years becomes Rp 287 million.

But deposits offer nominal return. With inflation averaging 4 to 5%, the real return on deposits approaches 0 to 1%. Solar savings naturally track PLN tariff inflation, meaning the real return is substantially higher and improves automatically every time PLN raises rates.

Equity mutual funds

Indonesian equity mutual funds have historically delivered 8 to 12% average return over long horizons (10 or more years), but with significant volatility. Some years run minus 20 to minus 30%. If you're comfortable with that volatility and don't need predictability, equity funds could outperform solar returns. But the comparison is not apples-to-apples: solar is a fixed commitment to a single asset, not a liquid portfolio you can rebalance.

Property

Indonesian property has historically appreciated 5 to 8% per year in major cities at prime locations. But property requires far more capital, carries high transaction costs (notary fees, BPHTB tax, sales tax), and is illiquid. Solar doesn't compete directly with property as an investment class; they're complementary. Installing solar on your home can meaningfully increase the resale value of the property.

Direct comparison: Rp 85 million over 25 years

Investment	Annual Return	End Value (Rp)	Risk	Liquidity
Bank deposit 5%	5% nominal	Rp 287M	Very low	High
Equity mutual fund 10%	10% average	Rp 917M	High	High
Property 7% appreciation	7% + transaction costs	Highly variable	Medium	Low
Solar on-grid	IRR 13 to 15% effective	Rp 170-195M savings	Low	Very low
Solar hybrid	IRR 11 to 13% effective	Rp 155-180M savings	Low	Very low

Important caveat: the solar figure is savings avoided, not terminal value. It cannot be directly compared to the ending balance of a deposit account. What can be compared is effective IRR: solar at 13 to 15% versus deposit at approximately 0 to 1% real (after inflation) or 5% nominal. Solar wins significantly on inflation-adjusted IRR.

Risk profile: Solar risk is actually lower than equity mutual funds. No daily volatility, no issuer-default risk. The main risks are: poor installation quality (mitigate: choose a warranted installer), premature inverter failure (mitigate: reputable brand plus warranty), and PLN tariff decreasing (historically very unlikely). For a sound approach to installer selection that manages these risks, the how to choose a solar installer guide covers everything you should verify.

Sensitivity analysis: if PLN tariff rises 3% vs 7%

Solar ROI is highly sensitive to the PLN tariff escalation assumption. This isn't a weakness, it's actually a strength: the more aggressively PLN raises tariffs, the better your solar ROI looks retroactively.

Scenario 1: PLN tariff rises 3% per year (conservative)

3% growth is close to standard inflation and well below the historical PLN trend of 5% or more. This is the "good for consumers, less exciting for solar ROI" scenario.

5 kWp system, Rp 85 million capex, Surabaya, 65% offset:

• Year-1 savings: Rp 7.95 million
• Payback: 9.8 years
• 25-year net: Rp 145 million
• Effective IRR: 12.3%

Still meaningfully positive. Payback at 9.8 years still leaves 15 years of free production afterward.

Scenario 2: PLN tariff rises 5% per year (base case)

This is the middle assumption used throughout this article, consistent with the 10-year historical trend.

• Year-1 savings: Rp 7.95 million
• Payback: 8.7 years
• 25-year net: Rp 195 million
• Effective IRR: 14.0%

Scenario 3: PLN tariff rises 7% per year (optimistic for solar)

7% annual increase has happened before, during the 2010 to 2014 gradual normalization period. If the government continues removing subsidies, 7% is realistic within the next decade.

• Year-1 savings: Rp 7.95 million
• Payback: 7.6 years
• 25-year net: Rp 265 million
• Effective IRR: 17.0%

Full sensitivity table

PLN Escalation	Payback	25-Year Net (Rp)	Effective IRR
0% (flat)	10.7 years	Rp 105M	10.5%
2%	10.1 years	Rp 126M	11.5%
3%	9.8 years	Rp 145M	12.3%
5% (base)	8.7 years	Rp 195M	14.0%
7%	7.6 years	Rp 265M	17.0%
10%	6.2 years	Rp 390M	21.0%

Takeaway from this sensitivity analysis: Even in the most conservative scenario (PLN tariffs completely flat for 25 years, a situation that has never historically occurred), solar ROI is still 10.5% IRR, well above deposits. In the realistic base case (5% escalation), 14%. In the optimistic scenario (7%), 17%. PLN cannot realistically freeze tariffs for 25 years, so the "flat" scenario is a genuine worst-case floor, not an expected outcome.

NPV and IRR for solar: the advanced math (optional reading)

This section is for readers who want to verify the numbers above methodologically, or want to compare solar against financial instruments using standard investment metrics.

The NPV concept

NPV (Net Present Value) is the difference between the present value of all future cash inflows (savings) and the initial investment. The basic formula:

NPV = -Initial_investment + Sum of: (Savings_year_t / (1 + r)^t)

Where r is the discount rate (the minimum return you require from this investment, for example 8%).

If NPV is positive, the investment meets your criteria. If negative, it doesn't.

Example NPV for 5 kWp system, 8% discount rate

Initial investment: Rp 85 million Year-1 savings cash flow: Rp 7.95 million, growing at 5% per year Maintenance: Rp 1 million per year Inverter replacement at year 12: Rp 10 million

Simplified NPV calculation:

For a growing annuity with growth rate g=5% and discount rate r=8% over n=25 years:

• PV = Savings_1 x (1 - ((1+g)/(1+r))^n) / (r-g)
• PV = 7.95M x (1 - (1.05/1.08)^25) / (0.08-0.05)
• PV = 7.95M x (1 - 0.489) / 0.03
• PV = 7.95M x 17.03 = Rp 135.4 million

PV of maintenance over 25 years at 8%: roughly Rp 10.7 million PV of inverter replacement at year 12 at 8%: Rp 10M / (1.08)^12 = Rp 3.97 million

NPV = 135.4M - 10.7M - 3.97M - 85M = Rp 35.7 million

A positive NPV of Rp 35.7 million means this investment generates Rp 35.7 million above your required 8% return. In plain terms: even if you demand a minimum 8% annual return from any investment, this solar install still clears that bar and delivers extra value.

The IRR concept

IRR is the discount rate that makes NPV equal to zero. This is the "effective interest rate" of your investment. For the 5 kWp Surabaya example with 5% PLN escalation, IRR is approximately 14%.

What this means: this investment is equivalent to placing your capital in an instrument generating 14% per year for 25 years, without default risk, with a built-in PLN inflation hedge.

Bank deposit at 5% IRR versus solar at 14% IRR: a 9% annual gap over 25 years on Rp 85 million of capital. That compounding difference is enormous.

Bottom line on advanced math: With conservative assumptions (8% discount rate, 5% PLN escalation), solar NPV is strongly positive and IRR substantially exceeds available low-risk investment alternatives in Indonesia.

Factors people forget when calculating payback

1. Panel degradation. Tier-1 panels degrade linearly at about 0.5% per year. By year 10, output is roughly 95% of new; by year 25, about 87.5%. This factors into total lifetime savings, not the payback calculation itself.

2. Inverter replacement. Inverters last 10 to 15 years. Replacement cost is roughly Rp 5 to 15 million per system. This goes into total cost of ownership, not the initial payback.

3. Maintenance and cleaning. Rp 200,000 to 500,000 per visit, 1 to 2 visits per year. So Rp 400,000 to 1 million per year. Knocks down annual savings slightly.

4. PLN tariff escalation. Historically 3 to 7% per year. Effectively shortens payback by 1 to 2 years on a present-value basis.

5. Future carbon pricing or subsidies. Can't be locked in for 2026. Treat as upside, not as an assumption.

When solar ROI goes negative: 5 scenarios to avoid

Solar ROI is not always positive. There are five scenarios where solar does not deliver a sensible return, and we state this directly because the goal is to recommend what is right for you, not to push panels.

Scenario 1: PLN bill under Rp 600,000 per month

A small bill means small potential savings. If your bill is Rp 500,000 per month and the minimum technically feasible system is 1.5 kWp at Rp 25.5 million, payback can stretch to 15 to 18 years even under optimistic assumptions. 25-year net may be minimal or negative after accounting for maintenance and inverter replacement. This profile is better served by energy efficiency improvements (LED lighting, inverter-type AC) before committing to solar.

Scenario 2: Severe roof shading

Shading from trees, neighboring buildings, or antennas can reduce panel output by 30 to 50%. A system that looks good on paper at 7,200 kWh per year may only deliver 4,000 to 5,000 kWh in practice due to shading. Payback shifts back by 2 to 4 years and 25-year net drops significantly. Partial solutions exist (microinverters, power optimizers, adjusted panel layout) but cost more. A proper roof survey is mandatory before commitment. The solar installation guide explains the survey process and what should be verified on site.

Scenario 3: Plans to move within 5 years

Solar panels are a fixed asset tied to the property. If you plan to sell or move within 5 years, there are two paths: leave the panels for the buyer (which may add resale value but not the full installation cost) or remove and reinstall at the new home with extra costs. Both scenarios reduce return. The financial case for solar requires at least 8 to 10 years of ownership to clear payback and deliver meaningful net savings. If you are uncertain about staying that long, defer the decision until your plans are clearer.

Scenario 4: Oversized system relative to actual usage

Sometimes homeowners install systems far larger than their current consumption, anticipating "future growth." If you install 6 kWp but actual daily consumption is only 8 kWh, daytime surplus that can't be self-consumed only earns 65% credit through net metering, not 100% of the tariff. Investment effectiveness drops. Right-sizing to actual consumption is consistently more efficient than speculative oversizing. Use the solar panel calculator for a proportional sizing estimate based on your real consumption.

Scenario 5: Poor brand quality and warranty issues

Panels or inverters from unknown brands with warranties that can't realistically be claimed transform the ROI calculation entirely. If an inverter dies in year 4 and the brand has no presence in Indonesia, replacement is fully out of pocket and the system produces nothing during downtime. If panels degrade twice as fast as rated (common in grade-B products), output by year 15 is far below original projections. Total cost of ownership rises, 25-year net drops, and in worst cases turns negative.

Solution: only purchase from brands with authorized distributors in Indonesia and verifiable warranty claim processes. For a systematic approach to installer vetting and brand quality assessment, how to choose a solar installer in Indonesia covers exactly this.

Five questions to answer before you contact any installer

Before calling a single installer, answer these five questions. If all answers point positive, you're ready to move into serious quoting.

1. What is your average PLN bill over the past three months? Not your peak month, but the 3-month average. Monthly bill variation can reach 20 to 30% depending on season (AC runs more during heat waves) or household occupancy changes. A 3-month average is more representative for annual savings calculations.

2. How many hours per day is someone actively home during daylight hours (roughly 9am to 3pm)? This is the most important question for offset rate. If the house is empty during the day (everyone at work or school), self-consumption rate can be quite low. If there is WFH or a full-time domestic worker, the offset rate rises significantly. An honest answer here can shift payback by 2 to 3 years.

3. Is there any shading on the roof? From trees, neighboring buildings, antennas, a water heater tank? Check your own roof before any installer survey. Shading you are not aware of can reduce production by 20 to 40%. A good installer will photograph the roof and show you a shadow analysis. If significant shading exists, ask whether microinverters or power optimizers are worth considering versus simply avoiding the shaded area in the panel layout.

4. How long do you plan to stay in this home? Under 8 years, the financial ROI case weakens substantially. Over 15 years, solar ROI is almost always solid. Between 8 and 15 years, it depends on your bill size and city. The solar installation guide covers what to verify during the survey process.

5. Can your cash flow support the upfront capex, or do you need to explore financing? A minimum 2.5 kWp system runs Rp 40 to 45 million. If that feels heavy, some installers offer KTA financing, leasing, or pay-as-you-go options. ROI with financing differs from cash purchase because loan interest enters the calculation. Know which scenario applies to you before comparing quotes.

When payback isn't the right metric

Sometimes payback isn't the most important number. Cases:

• Energy independence motivation. The value of not depending on PLN can't be priced in rupiah.
• Blackout backup (hybrid). The value of running through an outage isn't captured in monthly bill savings.
• Future cost avoidance. PLN tariffs are likely to keep climbing. Locking in your energy cost today is a hedge.
• ESG or villa branding. If your villa markets itself as eco-friendly, solar is a marketing asset.

When payback genuinely is too long

• PLN bill under Rp 700,000 per month (small home, infrequent AC).
• Severe roof shading. Output drops 30 to 50%.
• You're moving within 4 years. Payback won't complete before you sell.
• Nighttime-dominant usage plus the zero-export rule (Permen ESDM 2/2024 doesn't credit grid exports). Daytime surplus gets wasted unless you have a battery.

If any of these is you, solar might not be the most sensible move right now. Use the calculator for numbers specific to your home.

Common questions on solar ROI in Indonesia

What if PLN tariffs drop instead of rising?

A real decrease in PLN tariffs has not occurred in Indonesia since tariff liberalization in 2010. There have been freeze periods (2014 to 2017, 2020 to 2021 during COVID), but a freeze is different from a decrease. Even under a prolonged freeze (the 0% escalation scenario in the sensitivity table above), solar IRR holds at 10.5%. The most conservative realistic scenario still produces better returns than a bank deposit.

Does solar increase property resale value?

There is anecdotal data from real estate agents in Jakarta, Surabaya, and Bali suggesting that homes with functioning installed solar sell faster and slightly above comparable market price. Hard numbers are difficult to quantify because Indonesian property databases do not explicitly track solar premium. But if your system is under warranty, functioning, and well-documented (SLO permit, installation invoice, active monitoring app), that is a tangible selling point for buyers who are aware of long-term PLN costs.

Does the math change if I finance through a renovation loan?

Yes, significantly. If you add solar to a renovation KPR loan at 9 to 11% annual interest (common in Indonesia in 2026), that interest cost enters your ROI calculation as a real expense. Effective IRR of the system drops to 4 to 8% depending on loan tenor and rate. Still feasible if your bill is large (Rp 3 million or more) and the loan tenor is short (3 to 5 years). But with a moderate bill and a long tenor, financed ROI can approach breakeven or go slightly negative. Cash purchase or a short-term personal loan is substantially more efficient for ROI.

Calculate for your specific home

All the numbers in this article are illustrative with stated assumptions. The actual figures for your home depend on your bill, city, usage pattern, roof orientation, and shading. The solar panel calculator runs the kWp sizing, capex estimate, monthly savings, and payback calculation using your specific inputs.

If you want to understand the methodology behind the calculator output before contacting any installer, the complete solar panel calculator guide explains how to read the results and which assumptions are most sensitive to your specific profile.

If you'd rather talk it through directly, chat with us on WhatsApp. Send us your bill, location, and PLN connection rating. We'll give you a real range, not a sales pitch.