Solar Buyer Decision Tree 2026 — Pick System in 10 Questions

Most solar projects fail not at installation but at the decision stage — buyers walk into a quote conversation with a budget figure but no framework, get pitched a kW number that looks reasonable, sign the contract, and discover 18 months later that the system is undersized, the financing was wrong, or the vendor has disappeared. Across roughly 10,000 installations Heaven Green Energy has handled since 2018, the pattern is consistent: about 85% of failed solar projects skipped at least three of the ten decision questions that determine whether a system actually works for the building, the bill, and the next 25 years. This guide names those ten questions, walks through each one with the actual outcome it produces, and gives you a single framework — The Heaven Green Solar Buyer Decision Tree — 10 Questions — that takes 15–20 minutes to run and replaces 8–10 weeks of backtracking.

This is the originality anchor for everything else we publish — every Heaven Green blog post on kW sizing, PM Suryaghar (Pradhan Mantri Suryaghar: Muft Bijli Yojana), OPEX (operating expenditure) vs CAPEX (capital expenditure), and EPC (Engineering, Procurement, Construction) selection eventually ties back to one of these ten branches.

Direct answer. The Heaven Green Solar Buyer Decision Tree is a 10-question framework that maps your buyer type, monthly bill, sanctioned load, roof area, load growth, grid reliability, subsidy eligibility, financing model, vendor tier, and 25-year O&M (operations and maintenance) commitment to a specific outcome — system capacity in kW, finance route (CAPEX, OPEX/PPA, or loan), and vendor archetype. Residential buyers exit at a 3, 5, 7, or 10 kW recommendation with PM Suryaghar subsidy; commercial buyers exit at a CAPEX-with-AD (accelerated depreciation) or OPEX/PPA recommendation; off-grid buyers exit at a hybrid plus lithium battery recommendation.

The questions are sequenced — you cannot answer Q8 (financing) before Q1 (buyer type) and Q2 (bill). The tree is the order. Skip a step and you lose the dependency that makes the next answer correct.

Why Solar Buying Needs a Decision Tree — Not a Calculator

Online solar calculators are useful for one thing: producing a rough payback figure from a single input — the monthly bill. They are not decision tools. They do not ask whether you are residential or commercial, what your sanctioned load is, whether your roof can hold the calculated capacity, what your load growth will look like in three years, whether you need backup, whether OPEX makes more sense than CAPEX given your tax position, or whether the vendor quoting you will still be around in 2031. A calculator gives you a number. A decision tree gives you a system that survives 25 years.

The cost of a wrong decision is asymmetric. Get the kW figure wrong by 30% and you either waste capital on unused generation or undersize the system and continue paying the DISCOM (distribution company) for the shortfall — often the larger of the two errors because grid tariffs escalate 4–6% a year. Get the financing model wrong and a commercial buyer can leave 40% AD on the table that a competitor will capture instead. Get the vendor tier wrong and the inverter that should have lasted 12 years fails in year 4 with no recourse, because the installer who quoted you is no longer trading. Each of these failure modes maps to a specific question in the tree.

The other reason a calculator is insufficient: solar is not a product, it is a 25-year power purchase decision. Whether you build the asset yourself (CAPEX) or rent the output from a developer (OPEX/PPA — Power Purchase Agreement) is a question about your balance sheet, your tax position, and your appetite for asset ownership — none of which a calculator considers. The decision tree forces those questions to surface in the order that matters, before any quote is signed and before any roof drilling starts. We built the tree from 10,000+ install records — every entry on the question list exists because we have seen a project fail when that question was skipped. The framework is empirical, not theoretical, and it is what our consultation team uses on every inbound call. For a deeper breakdown of how sizing alone goes wrong, see our home solar system size guide — the decision tree wraps around that sizing logic and adds the eight other questions that sizing alone cannot answer.

The Heaven Green Solar Buyer Decision Tree — 10 Questions

Below is the sequenced framework. Answer them in this order. Each question’s answer either narrows the next question or terminates the branch with a recommendation. Skip questions only if you have already locked the answer through prior installations or audited consultation. The full ten-question list:

1. Are you residential, commercial, or off-grid?
2. What is your monthly electricity bill?
3. What is your sanctioned load on the bill?
4. How much usable roof or ground area do you have?
5. Will your load grow in the next 3 years (EV — electric vehicle, additional AC — air conditioning, factory expansion)?
6. Is your grid reliable, or do you need backup?
7. Are you eligible for the PM Suryaghar subsidy?
8. Will you finance via CAPEX or OPEX/PPA?
9. Will you go with a Tier-1 branded EPC or a local installer?
10. Who handles 25-year O&M (operations and maintenance)?

Q1: Are You Residential, Commercial, or Off-Grid?

The single biggest determinant of every downstream answer. Residential is a domestic-tariff connection installed at a house or flat, eligible for PM Suryaghar central subsidy of up to ₹78,000, and capped at 10 kW for net metering in most states. Commercial covers shops, offices, hotels, hospitals, factories, and any non-domestic LT (low-tension) or HT (high-tension) connection — these connections are not eligible for the central residential subsidy but qualify for 40% AD under Section 32 of the Income Tax Act, plus GST input credit, plus eligibility for IREDA (Indian Renewable Energy Development Agency) project financing. Off-grid is anything that cannot or should not interconnect with the DISCOM — remote farms, telecom towers, mountain homes, agri-pumping, border outposts.

This first branch immediately determines the next four questions. A residential answer pushes you toward bill-bracket sizing (Q2), PM Suryaghar (Q7), and either CAPEX or a small loan (Q8). A commercial answer pushes you toward AD-driven CAPEX or RESCO/PPA (Renewable Energy Service Company / Power Purchase Agreement) under OPEX (Q8) and Tier-1 EPC (Q9). Off-grid pushes you straight to Q6 (backup) and a hybrid+battery configuration. If you do not classify correctly at Q1, you waste 80% of the rest of the tree.

Q2: What’s Your Monthly Bill?

For residential buyers, the monthly bill is the single best proxy for kW sizing. We use four brackets that map cleanly to PM Suryaghar subsidy tiers and 1,500 kWh/kW/year generation assumptions in most Indian states.

Monthly bill	Recommended kW	Annual kWh need	PM Suryaghar subsidy
₹1,000–₹2,000	2 kW	~3,000	₹60,000
₹2,000–₹4,000	3 kW	~4,500	₹78,000 (max)
₹4,000–₹8,000	5 kW	~7,500	₹78,000
₹8,000–₹15,000	7–10 kW	~10,500–15,000	₹78,000
₹15,000+	10 kW + plan Q5 expansion	15,000+	₹78,000

For commercial buyers, the bill does not map by bracket — it maps by load factor. A ₹2-lakh monthly bill on a 100 kW connection at 0.4 load factor needs roughly 60–80 kWp (kilowatt-peak), but the same ₹2-lakh bill at 0.7 load factor in a hospital needs only 40 kWp and a lot more attention to time-of-use export. Commercial Q2 must be answered alongside the connected load and consumption profile, not bill alone. See our 3 kW vs 5 kW vs 10 kW home solar comparison for the residential bracket walkthrough.

Q3: What’s Your Sanctioned Load?

The number printed as “Sanctioned Load” or “स्वीकृत भार” on your DISCOM bill, expressed in kW. Your rooftop solar capacity in kW cannot exceed this figure under DISCOM net-metering rules in any Indian state. A home with 3 kW sanctioned load cannot install a 5 kW system without first filing a load enhancement application — typically a 15–25 day process with a one-time security deposit increase.

This question terminates the tree early for a meaningful share of buyers. If sanctioned load is 2 kW but the Q2 bracket recommendation is 5 kW, the buyer has two choices: file load enhancement first (then continue Q4 onward), or scale the system back to 2 kW (and lose Q2’s optimum). For commercial connections, the equivalent question is “contract demand” expressed in kVA (kilovolt-ampere); LT consumers up to 100 kW go through net metering, above that goes to gross or net-billing under most SERC (State Electricity Regulatory Commission) frameworks.

Q4: How Much Roof or Ground Area Do You Have?

The physical constraint that overrides everything else. Rooftop solar needs roughly 80–100 sq ft of shade-free, south-facing or south-east facing roof per kW for ALMM (Approved List of Models and Manufacturers — see MNRE ALMM register) Tier-1 mono-PERC panels in 2026. Ground-mount needs ~4–5 acres per MW (megawatt) but with much more flexibility on tilt and orientation. Total roof area is only the starting figure — subtract shadow zones from water tanks, parapets, lift rooms, dish antennas, and adjacent buildings.

For villas and bungalows, roof is rarely the constraint — see our Suryaghar for villa and bungalow guide for the 8–15 kW conversation. For 2-BHK and 3-BHK flats, the constraint flips: the roof is shared, the RWA (Resident Welfare Association) NOC (No Objection Certificate) becomes the gate, and the per-flat share rarely exceeds 1.5 kW. Commercial flat-roof factories and warehouses are the cleanest cases — large continuous areas, easy to ballast or anchor, minimal shading. If Q4 gives you 60% of the area your Q2 sizing demanded, the recommendation downsizes to fit Q4 — there is no other answer.

Q5: Will Load Grow in the Next 3 Years? (EV, AC, expansion)

The most-skipped question and the cause of the most after-the-fact remorse. Buyers size today and forget that in three years they will own an EV, will have added a third or fourth split AC, will have converted a balcony to a study with a fifth ceiling fan, or — in the commercial case — will have added a production line that doubles daytime consumption. The DISCOM bill grows. The solar capacity does not.

The right way to answer Q5 is to write down every load expansion you can foresee in the next 36 months and convert it to kWh per year. A 30 kWh EV charged from home 4 days a week adds roughly 6,000 kWh per year — that is a 4 kW system worth of generation, by itself. A new 1.5-ton split AC in Rajasthan adds 1,800–2,200 kWh of annual summer use. Add those forecast kWh to your current annual kWh, divide by 1,500, and that is your true kW requirement. For homes already considering significant load, our Suryaghar guide for 3-AC homes walks through the calculation for that specific load shape.

Q6: Grid Reliability — Do You Need Backup?

The DISCOM-quality question. If your grid is stable — under 20 hours of outage per year, no daily voltage sags — a straight grid-tied system is the right answer and a battery would only inflate cost and payback. If your grid is unreliable — 50+ outage hours per year, frequent monsoon trips, or any business-critical load (hospital ICU, data centre, cold storage, telecom) — the answer flips to hybrid solar with a lithium-iron-phosphate (LFP) battery.

The cost delta is large. A 5 kW grid-tied system in 2026 lands at ₹2.60–₹2.85 lakh; the same 5 kW with a 5 kWh LFP battery and hybrid inverter lands at ₹4.50–₹5.20 lakh. The right answer is not “battery for everyone” — it is “battery only where outage hours and load criticality justify the 70% cost premium.” Roughly 11% of Heaven Green residential buyers and 18% of commercial buyers in our 2025 data needed the hybrid+battery configuration. Q6 is also the only question with a hard NO branch — answer “grid is reliable” and you save ₹2 lakh on a typical residential install.

Q7: Are You Eligible for PM Suryaghar Subsidy?

Eligibility is narrow but high-value when met. The central PM Suryaghar: Muft Bijli Yojana under MNRE gives ₹30,000 for 1 kW, ₹60,000 for 2 kW, and ₹78,000 for any system 3 kW and above, capped at 3 kW for subsidy calculation. RWAs and group housing societies installing solar for common-area loads get ₹18,000 per kW. You qualify if: you are an individual residential consumer with a domestic-tariff DISCOM connection, the property is in your name (or you have a long lease with NOC), your Aadhaar is bank-linked for DBT (Direct Benefit Transfer), and your installer is empanelled on the pmsuryaghar.gov.in portal.

You do not qualify if you are a commercial consumer, a tenant without ownership papers, a builder pre-handover, or someone whose bank account is not Aadhaar-seeded. For commercial buyers, the equivalent capital incentive is AD (40% accelerated depreciation in year 1 under Section 32) plus GST input credit — financially larger than residential subsidy in absolute terms but only available to entities with taxable profit to depreciate against. For the full subsidy walkthrough across states, read our PM Suryaghar complete guide.

Q8: CAPEX or OPEX/PPA Financing?

The structural finance question. Under CAPEX you buy the system outright (cash, loan, or NMM — National Mission Mode financing), own the asset from day one, claim the subsidy or AD, and keep 100% of the generation. Under OPEX/PPA you sign a 15–25 year Power Purchase Agreement with a developer (the RESCO model), they fund and install the system, you pay only for the units you consume at a discounted ₹/kWh — typically ₹4.50–₹5.00/kWh for commercial PPAs in 2026, well under the ₹8–₹11/kWh commercial DISCOM tariff.

The decision is balance-sheet driven. CAPEX is correct when you have idle cash or cheap debt and a taxable profit (commercial) or a long ownership horizon (residential). OPEX/PPA is correct when you want zero upfront capex, no maintenance liability, and a clean line-item operating cost — typical for commercial tenants on long leases and asset-light businesses. Residential PPAs exist but are uncommon because the cost stack rarely beats the post-subsidy CAPEX route. For the full comparison, see our OPEX vs CAPEX 2026 guide.

Q9: Tier-1 Branded EPC or Local Installer?

The vendor tier question — and the one with the longest tail of regret. A Tier-1 EPC is an MNRE-empanelled, ALMM-using, BIS-certified-inverter integrator with a documented track record, in-house O&M, and a balance sheet that will survive the 25-year warranty window. A local installer is anything from an electrician with a side hustle to a regional outfit with 50 installs to its name. Both can complete a working installation in week 1. The difference shows up in year 4 when an inverter MPPT (Maximum Power Point Tracker) channel fails — the Tier-1 EPC handles the replacement under warranty; the local installer has changed its number.

There is a legitimate role for both. For systems under 3 kW in tier-3 towns where Tier-1 EPCs do not service, a vetted local installer using ALMM-listed panels can be the right answer. For systems above 5 kW, or any commercial installation, or any installation where 25-year warranty enforcement matters (it always does), the Tier-1 EPC is the only safe answer. Heaven Green Energy is empanelled across PM Suryaghar for residential and operates a separate commercial EPC division — that combination is rare and is what Q9 is really asking about.

Q10: 25-Year O&M Commitment — Who Handles It?

The question almost no buyer asks at the quote stage and every buyer asks at year 3. Solar panels carry 25-year linear output warranties and inverters carry 5–12 year product warranties — but warranty is not the same as O&M. Operations and maintenance is the actual work of monitoring generation, cleaning panels quarterly, tightening MC4 connectors annually, replacing fuses, rebooting communication modules, filing warranty claims when components fail, and managing the net-meter calibration when the DISCOM rotates meters. Nobody does this for free, and the vendor who quoted you Year 0 may not be the vendor doing it Year 7.

Three credible models exist: in-house O&M from the EPC (typically ₹800–₹1,500 per kW per year, bundled), third-party O&M (₹600–₹1,200 per kW per year, less integrated), or self-managed (₹0 paid but zero monitoring, which becomes negative ROI inside 4 years). Q10 closes the tree because it forces you to commit to a 25-year operational reality, not just a 0-year capex number. For the math on how O&M cost feeds into 25-year ROI, see our solar ROI calculation guide.

Residential Outcomes — Which System the Tree Recommends

Once you have walked the ten questions, the residential outcome map collapses to four primary configurations. Each carries a recommended kW, financing route, and vendor archetype. The mapping below is what our consultation team produces at the end of a 15–20 minute call.

Bill bracket	Sanctioned load	Load growth (Q5)	Recommended kW	Finance	Subsidy
₹2,000–₹4,000	3+ kW	No	3 kW	CAPEX	₹78,000
₹4,000–₹8,000	5+ kW	No	5 kW	CAPEX or loan	₹78,000
₹8,000–₹15,000	7+ kW	EV planned	7 kW	CAPEX + loan	₹78,000
₹15,000+	10+ kW	Heavy	10 kW	CAPEX + loan	₹78,000
Any bracket	Any	Backup needed	Equivalent kW + 5–10 kWh battery	CAPEX	₹78,000 (solar portion)

The 3 kW PM Suryaghar bracket is the highest-density outcome in our 2025 data — about 41% of residential exits land here because it is the sweet spot of bill, subsidy cap, and roof area. The 5 kW bracket is the next 28% — typical for a 3-BHK home with one or two ACs running 8 hours daily. The 7–10 kW bracket is where EV-owning households end up, and it is the fastest-growing segment in our 2025 vs 2024 data. The hybrid+battery outcome is small in count (11%) but high in average ticket size — these are villas in patchy-grid areas and homes with critical medical equipment.

Get the right outcome from question 1. Heaven Green Energy’s consultation team will walk you through all 10 questions in a 20-minute call and lock the right kW, finance route, and subsidy path before any quote moves. Book a free decision tree consultation →

Commercial Outcomes — Which Model the Tree Recommends

The commercial branch is shorter on the bill-bracket side but longer on the finance side. The two structural exits are CAPEX-with-AD and OPEX/PPA — and the determinant is your tax position and balance-sheet appetite.

Buyer profile	Connection size	Finance recommendation	Tariff outcome	Lock-in
Profitable SME, owned premises	25–100 kW	CAPEX + 40% AD	₹0/kWh marginal	None — full ownership
Profitable SME, leased premises (long lease)	25–100 kW	OPEX/PPA	₹4.50–₹5/kWh	15–20 yrs
Manufacturing plant, owned, profitable	100–500 kW	CAPEX + AD + IREDA loan	₹0/kWh marginal	None
Hospital, hotel, cold storage (uptime critical)	50–200 kW	CAPEX hybrid + battery	₹0.50–₹1/kWh equivalent	None
Asset-light services firm, leased office	25–100 kW	OPEX/PPA	₹4.50–₹5/kWh	15 yrs
Loss-making or low-profit entity	Any	OPEX/PPA	₹4.50–₹5/kWh	15–20 yrs

The CAPEX-with-AD outcome dominates manufacturing and owned-premises buyers because the 40% Section 32 AD plus 100% asset ownership plus zero ongoing tariff produces an internal-rate-of-return (IRR) of 18–24% on a 5-year horizon. The OPEX/PPA route dominates for asset-light businesses and leased-premises buyers — zero capex, zero maintenance, and a contracted ₹/kWh below DISCOM that drops to your bottom line as a clean operating saving. Roughly 38% of our commercial exits in 2025 chose OPEX over CAPEX — the share is growing year-on-year as PPA tariffs compress under IREDA-backed RESCO funding. For the full structural comparison, see OPEX vs CAPEX 2026.

Off-Grid + Hybrid Outcomes

Off-grid buyers exit the tree at a fundamentally different configuration. The recommendation here is always solar + lithium battery + diesel generator backup or solar + lithium battery alone — there is no DISCOM, no net metering, no PM Suryaghar subsidy, and no AD unless the buyer is a commercial entity claiming depreciation. Sizing is driven by daily kWh demand plus 1.5 days of autonomy (battery storage) plus a 20% oversizing margin to cover cloudy days.

Typical off-grid configurations from our 2025 install data: a remote farmhouse with 8 kWh daily demand needs ~3 kW solar + 12 kWh LFP battery + 3 kVA hybrid inverter, landing at ₹4.2–₹4.8 lakh. A telecom tower with 30 kWh daily demand needs 10 kW solar + 40 kWh LFP + 10 kVA hybrid, landing at ₹14–₹16 lakh. An agri-pumping setup with 5 HP (horsepower) submersible pump running 6 hours daily needs 7.5 kW solar with VFD (variable frequency drive) and no battery, landing at ₹4.5–₹5 lakh and often qualifying for the PM-KUSUM (Pradhan Mantri Kisan Urja Suraksha evam Utthaan Mahabhiyan) component-B 30% subsidy.

The hybrid outcome — grid-tied solar with battery backup but still on-grid — sits between residential CAPEX and off-grid. It uses a hybrid inverter that can island the home from a failed DISCOM grid using stored battery energy, then resynchronise when grid returns. This is the right answer for Q6 buyers who answered “grid unreliable” but still have a working DISCOM connection. The cost premium is 50–70% over straight grid-tied, and the recommendation is to size battery for critical loads only — fridge, lights, fans, modem — not the whole house.

Battery chemistry choice also matters at this exit. Lithium-iron-phosphate (LFP) is the 2026 default for residential and small commercial hybrids because of its 6,000+ cycle life, thermal stability in Indian summer conditions, and 10-year warranty windows from credible OEMs. Lead-acid tubular still appears in low-cost off-grid quotes but the 25-year economics rarely beat LFP once you factor in two battery replacement cycles. Off-grid agri buyers should also note that the PM-KUSUM component-B subsidy of 30% central plus 30% state (in eligible states) brings the effective project cost down by 60%, often shifting the decision back toward a battery-free direct-drive pump configuration rather than a battery-buffered one.

Common Mistakes When Skipping the Tree

These are the failure patterns we recover from most often — every one of them traces back to a specific question that was not asked, or was answered without data.

1. 1
   Skipping Q5 (load growth). The most common skip. Buyer sizes for today's bill, adds an EV 18 months later, and the 3 kW system covers 55% of the new demand. The retrofit cost is 30% higher than oversizing at install time.
2. 2
   Answering Q8 before Q1. Choosing OPEX/PPA before confirming the buyer is commercial. Residential PPAs almost never beat post-subsidy CAPEX — running the financing question first sends the buyer down the wrong branch entirely.
3. 3
   Ignoring Q3 (sanctioned load). Installer quotes 5 kW. Sanctioned load is 3 kW. DISCOM rejects the feasibility application. Buyer wastes 4 weeks before realising load enhancement should have come first.
4. 4
   Adding battery without answering Q6. Buyer in a reliable-grid area pays the 70% battery premium because the installer pushed hybrid as default. Payback extends from 4 years to 8+ years for no operational reason.
5. 5
   Choosing Q9 (vendor) on price alone. Local installer quotes 18% under Tier-1 EPC. Buyer signs. Inverter fails in year 4. Vendor unreachable. Replacement cost equals 60% of the original "saving."
6. 6
   Treating Q10 (O&M) as optional. Buyer skips O&M contract to save ₹800/kW/year. Panel soiling reduces generation 12% by year 2; no quarterly clean has happened. Annual revenue loss is double the O&M fee skipped.
7. 7
   Answering Q4 (roof) by eyeball. Buyer assumes "the roof is big." Site survey finds 40% of the area is shaded by an adjacent building between 11 am and 2 pm. Rated capacity has to drop from 5 kW to 3 kW after deposits are paid.

Every one of these maps to a question in the tree. Run the tree at consultation stage and the cost of catching the error is zero; catch it after installation and the cost is in the lakhs.

DIY Decision vs Heaven Green Consultation

You can absolutely walk the tree yourself. The questions are public, the data inputs are on your DISCOM bill, and the framework is reproducible. The trade-off is between time-cost and risk-cost — DIY is free in cash but expensive in the hours and the rework if a question is answered with the wrong data.

Verdict. Use the tree yourself for the first six questions — Q1 through Q6 are answerable from your bill and a rough roof estimate. Bring in a Heaven Green consultation for Q7–Q10 where subsidy eligibility, finance structuring, vendor selection, and 25-year O&M planning need empirical data. The split keeps you in control of the framework while removing the four risk-heavy questions where DIY fails most often.

The hybrid DIY-plus-consultation model is the highest-conversion path in our 2025 data — about 62% of buyers who walked the first six questions on their own before booking a call ended up with a faster contract close and higher post-install satisfaction scores than buyers who outsourced the whole decision. Self-running Q1–Q6 also surfaces the questions where you genuinely need outside help, which makes the consultation call sharper and shorter. The buyers who arrive having done none of the prep tend to want to “be sold” a system rather than diagnose one, and that is the buyer profile most likely to skip Q5 and Q10.

How Heaven Green Energy Walks Buyers Through the Tree

Our consultation process mirrors the ten questions one-to-one. The inbound call begins with Q1 buyer classification and ends with a written recommendation document covering kW, finance, vendor scope, and O&M proposal. The full process runs 20 minutes for residential and 45–60 minutes for commercial.

What we bring to each question: for Q2 and Q3, our team reads your actual DISCOM bill and pulls the sanctioned load and tariff slab directly — no estimates. For Q4, we either run a satellite-imagery roof estimate during the call or schedule a same-week site survey. For Q5, we run the load-growth calculator with your declared EV, AC, and expansion intent. For Q6, we pull the DISCOM outage history for your pincode. For Q7, we verify Aadhaar-bank seeding and ownership documents against the PM Suryaghar portal requirements. For Q8, we run both CAPEX and OPEX models side by side with the 25-year NPV (net present value). For Q9, we transparently scope ourselves as Tier-1 and offer comparison parameters. For Q10, we attach the O&M contract scope to the proposal so it never becomes a year-3 surprise.

The internal commitment we make: our installation success rate sits at 96% on-time vs 78% industry average per our 2024–25 data, because the decision tree is run before the contract is signed, not after. Explore the services that match your branch:

• Residential Solar — 1–10 kW rooftop systems with PM Suryaghar subsidy handled end-to-end and the full 10-question tree run at consultation.
• Commercial Solar — 25 kW–1 MW systems with CAPEX vs OPEX modelling, AD planning, and IREDA financing facilitation.
• Solar Calculator — answer Q1, Q2, Q4 in under a minute and see your indicative kW, subsidy, and payback.
• Free Consultation — book the full 10-question call.

For the question of how to map kW size to your specific bill, the most-read companion piece is our home solar system size guide. For the PM Suryaghar walkthrough that Q7 leads into, see the PM Suryaghar complete guide.

Frequently Asked Questions

How long does the Heaven Green Solar Buyer Decision Tree take to run?

Residential buyers complete all ten questions in 15–20 minutes when working with a consultation team that already has the data inputs ready. Commercial buyers run 45–60 minutes because Q2 (consumption profile), Q8 (CAPEX vs OPEX with AD modelling), and Q10 (multi-year O&M scoping) require more depth. Compared to the 8–10 week backtrack cycle that follows a wrong sizing decision, the time investment is trivial.

Can I skip questions if I already know I want a specific kW system?

You can, but you take the risk that the answers you already locked are inconsistent with the rest of the tree. The most common failure mode is buyers who arrive committed to 3 kW PM Suryaghar without running Q3 (sanctioned load) or Q5 (load growth) — and either get DISCOM-rejected or end up undersized within two years. Running the full tree even when you have a strong prior takes 15 minutes and validates your prior.

Does the decision tree apply to commercial buyers the same way as residential?

The ten questions apply, but the weighting changes. Q1 immediately diverges into a commercial branch with different subsidy logic (no PM Suryaghar; instead 40% AD and GST input credit), different financing (CAPEX vs OPEX/PPA both viable), and different vendor archetypes (always Tier-1 EPC for any system above 25 kW). Q2 in commercial is read as consumption profile, not bill bracket. Q8 carries the most weight in commercial because the financing structure determines the 25-year economics more than the kW size does.

What if my answers to two questions conflict — say Q3 sanctioned load says 3 kW but Q2 bill bracket says 5 kW?

The conflict is the answer. The tree is designed to surface exactly these conflicts so you can resolve them before contracting. The resolution is one of: file a DISCOM load enhancement first (15–25 days, then proceed with 5 kW), accept a 3 kW system (and lose Q2’s optimum), or split the install into 3 kW grid-tied plus 2 kW off-grid (rare but viable for some buyers). The point of the tree is that you make the call with full information, not that the installer makes it after the contract is signed.

Is the decision tree biased toward Heaven Green Energy’s products?

The framework is vendor-neutral — Q1 through Q8 do not reference any installer. Q9 asks the structural question of Tier-1 EPC vs local installer, and Q10 asks who handles O&M; in both we identify ourselves as a Tier-1 candidate but the tree explicitly invites comparison. We published the framework because we believe well-informed buyers make better long-term solar decisions, and well-informed buyers turn out to choose Tier-1 EPCs at higher rates anyway. The tree wins for us because better buyers stay better customers.

Does the tree change if I want batteries or off-grid?

Q6 is the branch point. Answer “grid unreliable” or “off-grid” at Q6 and the tree pushes you toward hybrid + battery (still-on-grid) or pure off-grid (battery + optional diesel backup). The downstream questions then shift: Q7 (PM Suryaghar) still applies to the solar portion of a hybrid system but not to the battery; Q8 (CAPEX vs OPEX) defaults to CAPEX for off-grid because PPAs require grid interconnection in most cases. The other questions — sizing, vendor, O&M — remain the same.

How often should I re-run the decision tree after the first install?

Re-run Q5 (load growth) every 18–24 months, especially after any major load change — EV purchase, factory expansion, new AC. If Q5 has shifted by more than 30%, run Q2 again and consider a phase-2 add-on installation. The other questions are relatively stable: Q1, Q3, Q4 do not change unless you move premises; Q7, Q8, Q9, Q10 are locked at the first install. Q6 (grid reliability) is worth rechecking if the DISCOM outage profile has shifted in your pincode.

What is the single most-skipped question — and why?

Q5 — load growth in the next three years. The skip happens because buyers underestimate their own load trajectory. They are looking at the current bill, not the EV they will buy in 18 months, the third AC they will add next summer, or the second floor they will build out in 2027. We see undersized systems in 34% of audited installs where the buyer did not work with a tree-running consultant. Future-proofing with an additional 1–2 kW headroom is almost always cheaper than retrofitting later.