You installed a 3 kW (kilowatt) rooftop system in 2022, took the PM Suryaghar subsidy, and watched your monthly bill collapse from ₹4,200 to ₹600. Three years later the situation has shifted — a second AC went up in the bedroom, your daughter is back from college and runs a desktop workstation, and last month you took delivery of a Tata Punch EV with a home charger sitting in the box waiting for someone to wire it. The first 100 watts (W) of new load are easy. The next 1,500 watts are the problem — and the question that lands in our Jaipur office almost every working day is, “Can we just add panels to what I already have?” Sometimes yes, often no, and the path you pick depends on four factors most homeowners don’t think to check.
Direct answer. Existing solar systems can be upgraded along four paths: (1) add more panels within the inverter’s DC oversizing headroom (~130%) at ₹50,000–₹80,000 per kW (kilowatt); (2) replace the inverter with a higher-rated or hybrid unit at ₹30,000–₹70,000 for 5–10 kW; (3) add a lithium battery for backup or self-consumption at ₹1–₹2 lakh for 5–10 kWh (kilowatt-hour); (4) add an EV (electric vehicle) charger at ₹15,000–₹40,000 for a 3.3 kW AC (alternating current) wallbox or ₹50,000–₹1 lakh for a 7.2 kW unit. Net Metering (NMM) residential cap remains 10 kW.
If you fall into the third path or the fourth, batteries and EV chargers are now the dominant upgrade reason we see in Rajasthan — about 35% of our 2021–2023 customers come back within five years. The rest of this guide walks each path, the cost and ROI maths, and the four constraints (inverter headroom, NMM cap, structure load, subsidy eligibility) that decide which path you actually qualify for.
Why Solar Owners Upgrade Within 3-5 Years
The standard sales pitch in 2020–2022 was “size for current consumption” — and almost every installer including us sold 2 kW and 3 kW systems because that’s what the PM Suryaghar subsidy capped at and what fit most monthly bills. The arithmetic was right for the moment, wrong for the trajectory.
What changed between then and now: household load profiles shifted. Average urban electricity consumption in tier-1 Indian cities has grown roughly 6–8% per year through 2024–25, driven by a second or third AC, an induction cooktop replacing the LPG stove, a clothes dryer in monsoon months, and an EV in the driveway. A home that consumed 350 kWh per month in 2022 is consuming 550–650 kWh per month today. The 3 kW system that covered 90% of the bill now covers 50%.
Across Heaven Green’s residential portfolio, roughly 35% of 2020–2022 installations request an upgrade quote within 5 years. Half of those go through with the expansion. The trigger is almost always a single event — an EV booking, a baby on the way, a third AC, or a parent moving in. The upgrade decision then comes down to which of the four paths the existing system can support without expensive rip-and-replace work.
The 4-Path Solar System Upgrade Decision Tree
Every upgrade conversation we run starts with the same four-way fork. Each branch has its own qualifying check, its own cost band, and its own subsidy and net-metering implication. We call this The 4-Path Solar System Upgrade Decision Tree — name it, work through it, and you’ll know within ten minutes which path your existing system supports.
| Path | When to pick it | Cost range (2026) | Key constraint |
|---|---|---|---|
| 1. Add more panels | Bill rose 30–60%, existing inverter has DC headroom | ₹50,000–₹80,000 per kW | Inverter DC input rating, roof space, NMM cap |
| 2. Replace inverter | Old inverter near end-of-life, going hybrid, system size jumping >2 kW | ₹30,000–₹70,000 for 5–10 kW | String compatibility, MPPT count, BIS certification |
| 3. Add battery | Frequent outages, time-of-day tariff arriving, want self-consumption | ₹1–₹2 lakh for 5–10 kWh | Needs hybrid inverter; replace if on-grid only |
| 4. Add EV charger | New EV in household, daytime charging possible | ₹15,000–₹40,000 (3.3 kW) / ₹50,000–₹1 lakh (7.2 kW) | Sanctioned load, single vs three-phase, AC vs DC |
The first three paths interact — adding panels often forces an inverter swap, adding a battery almost always forces a hybrid inverter swap, and stacking all three is a complete system overhaul that’s typically cheaper to engineer in one visit. The fourth path is independent — an EV charger talks to the grid through a separate breaker and only loosely couples to your solar generation.
For the underlying sizing maths behind each path, the home solar system size guide and the 3 kW vs 5 kW vs 10 kW home solar 2026 comparison cover the per-kW economics that decide which target capacity makes sense after the upgrade.
Path 1 quick check: Add More Panels
Look at your existing inverter’s nameplate. If it reads “5 kW” output with a DC input rating of 6.5 kWp (kilowatt-peak), you have 1.5 kWp of headroom — that’s three to four extra 450W panels. Roof space available? Path 1 is open.
Path 2 quick check: Replace Inverter
If the new target system size exceeds the existing inverter’s DC oversizing limit (typically 130% of AC output), the inverter must be replaced. Also a trigger: any move to a battery (requires hybrid) or any move past a 10 kW boundary that re-classes you into net-billing.
Path 3 quick check: Add Battery
A battery only makes financial sense if your DISCOM has time-of-day tariffs, you face frequent outages, or you want to maximise self-consumption because export tariffs are low. In Rajasthan that’s most JVVNL/JdVVNL residential consumers — but the payback is still 7–10 years, not 3–4. Read it as resilience, not pure savings.
Path 4 quick check: Add EV Charger
EV charger sits on your existing sanctioned load. A 3.3 kW slow charger (L1) is fine on a standard 5 kW single-phase connection. A 7.2 kW fast charger (L2) usually needs a load enhancement to 8–10 kW or a three-phase upgrade. Solar coupling is logical (charge during the day from your own panels) but mechanically the charger is a load like any other.
Path 1: Adding More Panels — Inverter Headroom + DC Oversizing
Adding panels is the cheapest path per incremental kWh because you reuse the inverter, the AC cable, the meter, and the existing net-metering paperwork. The question is whether your inverter has the DC input headroom to accept the new panels.
DC oversizing rule. Modern string inverters specify two ratings: AC output (what they push to the grid, e.g., 5,000 W) and DC input window (the maximum kWp of panels they accept, often 130% of AC). A 5 kW inverter with a 130% DC oversizing limit accepts up to 6.5 kWp of panels — anything beyond is clipped during peak sun hours. The clipping loss is small (typically 2–4% of annual generation) because peak DC output occurs only in narrow midday windows.
Inverter headroom check. Pull out the inverter datasheet. Look for “Max PV Input Power” or “Max DC Input”. Subtract your existing installed kWp. The remainder is your headroom. A 3 kW system on a 3.3 kW inverter has ~0.3 kWp headroom — barely one panel. A 3 kW system on a 5 kW inverter has 2.5 kWp of headroom (eight more 415W panels). The latter customer is who Path 1 was built for.
Roof structure load check. Each additional panel adds ~22 kg (panel + frame). A row of 8 panels adds ~180 kg distributed across the existing MMS (Module Mounting Structure). Most galvanised-steel MMS installed since 2020 are rated for 25–30% additional load without re-engineering. If your installer used aluminium-only rails or skipped corrosion treatment, get a load review before adding.
NMM impact. Adding panels usually does not require a net-meter change — the meter is bi-directional and rated for the inverter’s AC output, which has not changed. You do need to file an upgrade declaration with your DISCOM so their feasibility database reflects the new installed kWp. This is paperwork, not new hardware. If the upgrade pushes total capacity above the 10 kW NMM cap, the system reclassifies into net-billing — at which point the economics of the extra capacity weaken substantially.
| Existing inverter | Headroom (130% DC) | Extra panels possible | Extra annual generation |
|---|---|---|---|
| 3 kW (with 3 kWp installed) | 0.9 kWp | 2 panels (450W) | ~1,400 kWh |
| 5 kW (with 3 kWp installed) | 3.5 kWp | 7–8 panels (450W) | ~5,100 kWh |
| 5 kW (with 4 kWp installed) | 2.5 kWp | 5–6 panels (450W) | ~3,700 kWh |
| 8 kW (with 5 kWp installed) | 5.4 kWp | 12 panels (450W) | ~7,900 kWh |
| 10 kW (with 7 kWp installed) | 6 kWp | 13 panels (450W) | ~8,800 kWh |
Subsidy note. PM Suryaghar central subsidy was claimed on the original commissioning. Capacity additions do not qualify for a fresh subsidy under MNRE’s 2024 clarification — the subsidy is a one-time household benefit, not a per-kW rolling credit confirmed via the PM Suryaghar portal FAQ. Plan Path 1 upgrades on the un-subsidised price.
Path 2: Upgrading Inverter — When to Replace vs Add
There are four triggers that force an inverter replacement: end-of-life (8–10 years for older transformer-based units), insufficient DC input window for your target capacity, moving to a hybrid for battery integration, or moving to a three-phase output for an EV charger. The first is age-driven, the next three are upgrade-driven.
End-of-life signal. String inverters carry a 5–10 year manufacturer warranty. After year 8, capacitor degradation becomes the dominant failure mode — you’ll see efficiency drop 2–4 percentage points, occasional under-voltage trips, and elevated cabinet temperature. If your inverter is past warranty and showing any of these signs, plan the replacement before it fails outright. A planned swap is a 4-hour job; an emergency swap is two weeks of zero generation.
On-grid vs hybrid decision. If you’re going to add a battery anytime in the next three years, replace once with a hybrid (battery-ready) inverter — not twice. Hybrid inverters carry a 15–25% price premium over on-grid units of the same kW rating but eliminate the second visit and the second commissioning cycle. The full sizing logic is in our solar inverter replacement guide.
MPPT count and string compatibility. A 5 kW inverter typically has 2 MPPTs (Maximum Power Point Trackers); a 10 kW unit has 2–3. If your roof has multiple orientations (east + west, or front + back), each orientation should land on its own MPPT for highest yield. When upgrading, verify the new inverter’s MPPT count matches or exceeds your roof string layout.
BIS and ALMM compliance. Replacement inverters must carry the BIS (Bureau of Indian Standards) safety certification and be on the MNRE ALMM list for the system to retain net-metering eligibility. The ALMM list itself is maintained on the ALMM portal at mnre.gov.in/almm and is refreshed quarterly. Off-list inverters work technically but invalidate your DISCOM agreement.
| Inverter swap scenario | Recommended new inverter | Indicative price (2026) | Reason |
|---|---|---|---|
| 3 kW on-grid → 5 kW on-grid | 5 kW string, 2 MPPT | ₹30,000–₹40,000 | Capacity expansion only |
| 5 kW on-grid → 5 kW hybrid | 5 kW hybrid, battery port | ₹50,000–₹65,000 | Battery integration |
| 5 kW on-grid → 10 kW hybrid | 10 kW hybrid, 3 MPPT | ₹70,000–₹95,000 | Capacity + battery + EV |
| Single-phase → three-phase 10 kW | 10 kW three-phase | ₹65,000–₹90,000 | EV fast charger / large AC load |
Pause and price the next 5 years first. Before you swap an inverter to support battery + EV later, get a written upgrade roadmap. Heaven Green’s residential team builds a 5-year capacity, battery, and EV plan tied to your bill trajectory so you don’t pay twice for the same wiring. Get your free roadmap →
Path 3: Adding Battery Storage to a Grid-Tied System
Battery additions are the upgrade we get most asked about and most often talk customers down from. The honest answer in 2026 is that a battery makes financial sense for fewer than 30% of Indian residential solar owners — and even where it makes sense, it’s a resilience purchase, not a savings multiplier.
Why most existing systems can’t take a battery directly. A grid-tied (on-grid) inverter has no battery port and no logic for charging or discharging a DC storage block. Adding a battery means either replacing the inverter with a hybrid unit (the cleaner answer) or adding an AC-coupled battery system with its own dedicated inverter (more expensive, more components, slightly less efficient). The hybrid replacement is the recommended path for systems under 10 kW.
Battery chemistry choice. Lithium iron phosphate (LFP) batteries dominate 2026 residential installations — 6,000+ cycle life, 90% depth of discharge, 10-year warranties from Indian and global brands. Lead-acid (tubular) costs roughly 40% less upfront but lasts 4–5 years against LFP’s 10–12, so per-kWh-delivered it’s more expensive. The deep comparison is in our lithium vs lead-acid 2026 guide.
Sizing the battery. Two questions: how much backup do you need during an outage (resilience sizing), and how much surplus solar do you want to time-shift to evening loads (self-consumption sizing). Most homes settle on 5 kWh (covers fridge + fans + lighting + Wi-Fi for 8–10 hours) or 10 kWh (adds 1–2 hours of AC). Going beyond 10 kWh on a residential system rarely pays back.
Subsidy and NMM impact. PM Suryaghar does not subsidise batteries. The battery sits on the DC side of the hybrid inverter and is invisible to the DISCOM’s net meter — no fresh NMM application required as long as the inverter AC output rating is unchanged. If the inverter rating goes up at the same time, file the upgrade declaration.
| Battery option | Usable capacity | Indicative price | Best use case |
|---|---|---|---|
| 5 kWh LFP (lithium) | 4.5 kWh | ₹1.0–₹1.4 lakh | Frequent short outages, essential loads only |
| 10 kWh LFP (lithium) | 9 kWh | ₹1.8–₹2.4 lakh | Long outages or evening AC self-consumption |
| 5 kWh lead-acid tubular | 3 kWh | ₹55,000–₹75,000 | Tight budget; accept 4–5 year replacement cycle |
| AC-coupled retrofit (5 kWh) | 4.5 kWh | ₹1.4–₹1.8 lakh | Keeps existing on-grid inverter; higher complexity |
Path 4: Adding EV Charger — DC vs AC, Home Wallbox
EV charging is the fastest-growing upgrade category for us in 2026 — driven directly by the Tata Nexon EV, MG Comet, and Mahindra XUV400 deliveries through 2024–25. Charger choice is determined by daily kilometres driven, battery size, and whether you charge overnight or during solar peak hours.
AC vs DC charging. Home chargers are almost always AC — the car’s onboard charger does the AC-to-DC conversion. DC fast chargers (50 kW+) are highway / public infrastructure, prohibitively expensive for home (₹5–₹15 lakh installed) and require a dedicated transformer. For residential, the choice is between AC Level 1 (3.3 kW slow) and AC Level 2 (7.2 kW or 11 kW fast).
3.3 kW (L1) wallbox. Adds ~15 km of range per hour. A car driven 40–50 km daily fully recharges overnight (8 hours). Runs on single-phase and a standard 16A breaker. No load enhancement typically needed for homes with 5 kW or higher sanctioned load. Install cost ₹15,000–₹40,000 depending on wallbox brand and cable run.
7.2 kW (L2) wallbox. Adds ~35 km of range per hour. A 50 kWh EV charges from 20% to 80% in ~5 hours. Runs on single-phase but draws 32A — most installations need a load enhancement to 8–10 kW sanctioned. Install cost ₹50,000–₹1 lakh including wallbox, MCB, and cable.
Solar-coupled charging. The cleanest match: charge during 10 AM–4 PM when your solar panels are generating peak, so the kWh going into the EV is free at the margin (no grid import). Smart wallboxes (Hesla, Exicom, ABB) modulate charging speed to match excess solar generation in real time — a feature called “solar mode” or “solar-only charging”. Worth the extra ₹8,000–₹15,000 if the EV is parked at home during daytime hours. The integration patterns are covered in detail in our Suryaghar with EV charging guide and the EV charger plus solar guide.
Sanctioned load and three-phase. The single largest mistake homeowners make is installing a 7.2 kW charger on a 3 kW sanctioned-load connection. The DISCOM’s meter trips, repeatedly. File a load enhancement first; expect 15–25 days for JVVNL/JdVVNL/AVVNL territory.
Costs and ROI for Each Upgrade Path
Capacity additions pay back faster than battery additions and battery additions almost never out-pay capacity additions in pure rupee terms. EV chargers don’t have an ROI in the savings sense — they’re an enabler for the EV, and the underlying economic question is fuel cost replacement (petrol → electricity).
| Upgrade path | Capex (typical) | Annual savings / value | Payback | Notes |
|---|---|---|---|---|
| Add 2 kW panels (Path 1) | ₹1.0–₹1.6 lakh | ₹28,000–₹35,000 | 3.5–5 yrs | No fresh subsidy; cheapest per kWh |
| Replace 5 kW inverter (Path 2) | ₹50,000–₹65,000 | Marginal — enables Paths 1 / 3 | n/a alone | Counts as enabling capex |
| Add 5 kWh LFP battery (Path 3) | ₹1.0–₹1.4 lakh | ₹6,000–₹12,000 + resilience | 8–12 yrs | Resilience purchase, not pure ROI |
| Add 3.3 kW EV charger (Path 4) | ₹15,000–₹40,000 | ₹40,000–₹70,000 fuel replaced | <1 yr | Vs petrol at ₹105 + 15 km/L |
| Full stack: 2 kW + hybrid + 5 kWh + 7.2 kW EV | ₹3.5–₹4.5 lakh | ₹80,000–₹1.2 lakh combined | 3.5–5 yrs | Single mobilisation cheaper than four visits |
For the per-kW economics that anchor these numbers, run your bill through the Heaven Green solar calculator — it accounts for your existing system and quotes the marginal upgrade only.
Common Upgrade Mistakes
The five mistakes below show up in roughly 80% of failed or sub-optimal upgrades we’ve audited. None of them are technical hard problems — all are 10-minute pre-check failures.
-
1
Adding panels without checking inverter DC input. Buys panels that get clipped 8–12% of the year because the inverter caps DC input below installed kWp. Always confirm headroom against the inverter datasheet before quoting panel addition.
-
2
Assuming PM Suryaghar applies to the upgrade. It doesn't — the subsidy is a one-time household benefit. Budget the capacity addition at the un-subsidised price; otherwise the ROI maths will be off by 30–40%.
-
3
Adding a battery to an on-grid inverter via cheap AC-coupling. Works in principle, fails in resale value, warranty terms, and round-trip efficiency. Replace with a hybrid inverter once — cheaper net-net than the AC-coupled retrofit plus eventual replacement.
-
4
Installing a 7.2 kW EV charger without load enhancement. The DISCOM meter trips every time you charge in the evening. File the load enhancement first — 15–25 days, well worth it.
-
5
Crossing the 10 kW NMM cap without re-paperwork. Above 10 kW residential reclassifies to gross or net-billing depending on state. Surplus export tariff drops sharply. Re-apply through the DISCOM portal before going past 10 kW total installed.
⚠️ Watch out
Vendors who sold you the original system in 2020–2022 may not be active in 2026, and the AMC paperwork often expires after the warranty period. Before upgrading, get a written confirmation of the existing inverter model, panel ALMM tier, and MMS structural rating from any qualified installer — Heaven Green does this free as part of the upgrade audit.
Capacity Add vs Battery Add — Which Wins
Eight out of ten upgrade quotes we run end in capacity addition winning the spreadsheet. The exceptions are homes with poor grid reliability (load-shedding 3+ hours/day), homes in states with time-of-day residential tariffs (Maharashtra, parts of Gujarat from 2025), and homes where the owner explicitly values energy resilience over rupee payback.
- Pro 3.5–5 year payback on every added kW
- Pro Lower per-kWh cost than any storage option
- Pro No new battery replacement cycle to fund
- Con No backup during grid outage
- Con Roof space and inverter headroom constrained
- Pro Backup during outages, no diesel generator needed
- Pro Higher self-consumption ratio (80–95%)
- Pro Hedges against future ToD tariffs
- Con 8–12 year payback on rupee basis
- Con Battery replacement at year 10–12 adds capex
Verdict. Pick capacity add first if your bill is still above ₹2,000 post-existing-solar — every kW you add pays back inside 5 years. Add a battery only when grid reliability is bad enough that you’d otherwise buy a diesel generator, or when your state moves to time-of-day residential tariffs. EV charger sits on a different decision branch — install whenever the EV arrives, sized to the sanctioned load you can reach in 30 days.
How Heaven Green Energy Handles Solar Upgrades
Heaven Green Energy runs a dedicated upgrade audit team for existing solar systems — yours or someone else’s. The audit takes 90 minutes on-site (or 30 minutes via WhatsApp photo handoff for simpler cases) and produces a written 5-year upgrade roadmap with quoted capex bands for each path.
- Inverter datasheet pull — we identify your installed inverter model and pull the DC input window, MPPT count, and warranty status from the manufacturer database.
- DC oversizing headroom calculation — exact kWp of panels addable without inverter swap.
- MMS structural review — confirm the existing module mounting structure can take the added panel weight, or quote a reinforcement.
- Net-metering filing — handle the DISCOM paperwork for the upgrade declaration; coordinate with JVVNL / JdVVNL / AVVNL renewable energy cells.
- Hybrid inverter + battery design — sized to your outage profile and evening load curve, not to a salesperson’s stock list.
- EV charger + load enhancement — co-filed with the DISCOM so the wallbox commissions on the same week as load enhancement approval.
- Single-mobilisation pricing — when you’re doing two or three paths together, we price the combined visit instead of stacking three site fees.
Useful next steps:
- Residential Solar — full residential service page covering new installs and upgrades.
- Solar Calculator — quote your upgrade marginal cost in 60 seconds.
- Contact Us — book a free upgrade audit with the Heaven Green Jaipur team.
Frequently Asked Questions
Can I add panels to my existing solar system without changing the inverter?
Yes, if your inverter has DC input headroom. Modern string inverters typically accept up to 130% of their AC output rating in DC panel capacity — so a 5 kW inverter can take up to 6.5 kWp of panels. Subtract the kWp already installed; the remainder is your headroom. A 3 kWp system on a 5 kW inverter has 3.5 kWp of room — that’s seven to eight more 450W panels. Always confirm the exact DC input rating from the inverter datasheet before quoting.
Does PM Suryaghar subsidy apply when I upgrade my existing solar system?
No. PM Suryaghar central subsidy is a one-time benefit per household, claimed at the original commissioning. Capacity additions, inverter replacements, and battery additions do not qualify for a fresh subsidy under MNRE’s 2024 clarification. Plan all upgrade economics on the un-subsidised price. The only scenario where a fresh subsidy applies is if the original installation was below 3 kW and never claimed the maximum — but even then, the portal requires a new application that most existing customers cannot file.
How much does it cost to upgrade a 3 kW solar system to 5 kW?
For a 3 kW system being expanded to 5 kW, expect ₹1.0–₹1.6 lakh — ₹50,000–₹80,000 per added kW for panels and structure, plus ₹0–₹65,000 if the existing inverter needs replacement. If your existing inverter is a 5 kW unit with DC headroom, no inverter swap is needed and the cost stays near the lower end. If you have a 3 kW inverter, plan on a full inverter replacement bringing the upgrade closer to ₹2 lakh.
Do I need to re-apply for net metering when I upgrade my solar system?
You file an upgrade declaration with your DISCOM so their database reflects the new installed kWp. This is paperwork, not new hardware — the bi-directional meter usually does not change because the inverter AC output rating governs metering, not panel capacity. If you cross the 10 kW residential NMM cap, you must re-apply because the system reclassifies to gross-metering or net-billing rules with different export tariffs.
Can I add a battery to my existing on-grid solar inverter?
Not cleanly. On-grid (grid-tied) inverters lack a battery port and battery management logic. The two options are: (a) replace the inverter with a hybrid unit that natively supports battery — cleaner, single point of failure, ₹50,000–₹95,000 for the inverter; or (b) add an AC-coupled battery system with its own dedicated battery inverter — more components, slightly lower round-trip efficiency, ₹1.4–₹1.8 lakh for a 5 kWh setup. Hybrid replacement is the recommended path for residential systems.
Which EV charger should I install if I have a 3 kW solar system?
A 3.3 kW AC Level 1 (L1) wallbox is the right starting point. It draws 16A on single-phase, fits within most 5 kW sanctioned residential loads without enhancement, and refills 15 km of range per hour — enough to top up an average commuter EV overnight. If your daily driving is above 80 km or you have two EVs, step up to a 7.2 kW AC Level 2 (L2) wallbox and file for a sanctioned-load enhancement to 8–10 kW. Solar coupling works best on the L1 charger because its draw matches typical residential daytime solar generation.
How long does the entire upgrade process take from quote to commissioning?
For Path 1 (panels only, no inverter change), 5–7 working days including DISCOM upgrade declaration. For Path 2 (inverter replacement), 3–5 working days because the swap is a 4–6 hour job plus paperwork. For Path 3 (battery + hybrid inverter), 7–10 working days because of inverter procurement lead time. For Path 4 (EV charger), 1–3 days if no load enhancement is needed, 18–28 days if a load enhancement is required. A combined upgrade (all paths in one visit) runs 12–18 days end-to-end.
Will my existing solar warranty stay valid if I upgrade with a different installer?
The panel warranty (typically 25–30 years performance, 10–12 years product) stays with the panel manufacturer and is not affected by a different installer. The inverter warranty stays with the inverter manufacturer if the inverter is unchanged. The installation workmanship warranty from your original installer usually voids if a third party works on the system — read the original AMC carefully. Heaven Green issues a fresh workmanship warranty on the upgraded portion of the system and documents the existing equipment in writing to preserve manufacturer-side coverage.
