Skip to main content
Skip to main content

Build your solar plan — no payment until you approve

Configure solar
Shading GuideUpdated 2026

How Much Solar Power Are You Really Losing to Shade?

Shade is the silent thief of solar energy. In Malaysia’s dense urban and suburban landscape — palm trees, rain trees, neighbor buildings, water tanks — partial shading can silently rob your system of a meaningful share of its output (14-19% in the example scenarios below). This guide reveals exactly what’s happening electrically, how much it costs you in ringgit, and what you can do about it.

12 min readBased on Malaysian sun-path and irradiance dataBy Chandra Rau, CEO, Trexon Energy • SEDA-registered installer
14–19%
est. annual loss
String inverter on partially shaded roof
10–20%
of output
can be lost to partial shading on a string-inverter roof
7–10yr
payback
for micro inverter upgrade on shaded roof

Table of Contents

  1. 1Understanding Solar Shading
  2. 2Common Shading Scenarios
  3. 3Shading Loss Calculator
  4. 4Illustrative Scenarios
  5. 5Solutions for Shaded Roofs
  6. 6Malaysia 2026 Cost Comparison
  7. 7FAQ
1

Understanding Solar Shading

The physics of why one shadow ruins your whole system

Solar panels generate electricity using the photovoltaic effect — photons from sunlight knock electrons loose from silicon cells, creating DC current. When shade blocks those photons, that panel’s current drops dramatically. The problem isn’t just the shaded panel itself — it’s what happens to the entire string.

In a standard string inverter system, panels are wired in series. Electricity flows like water through a chain of hoses — the flow rate is determined by the narrowest hose. A shaded panel becomes that narrow hose, choking the current for every other panel in the string. This is why a single tree branch hitting one panel at 2pm can cost you several hundred ringgit a year (see the scenarios below).

The Christmas Light Effect

Think of old-style Christmas lights wired in series. One burnt-out bulb — the whole string goes dark. Solar panels in a string inverter system work the same way. One shaded panel at 30% output drags the whole string to 30% output. Modern bypass diodes help somewhat, but the physics can’t be fully overcome without panel-level electronics.

How Bypass Diodes Partially Help

Modern panels have bypass diodes — typically 3 per panel, one for each cell row. When a row is shaded below a threshold, the diode short-circuits that row, allowing current to flow around the shaded cells. This prevents a complete string shutdown. However, it means that shaded row produces zero output, and the panel loses 33% of its capacity instantly.

String Inverter vs Micro Inverter Shading Response

String Inverter — Shade Kills the Whole String

One shaded panel limits current for the entire string

30%
30%
SHADE
30%
30%
30%
Series Wiring — current limited to 30%
STRING INVERTER30% output
System output: ~30% (entire string limited by shade)

Micro Inverter — Only Shaded Panel Affected

Each panel operates independently — shade is isolated

μ
100%
μ
100%
SHADE
μ
30%
μ
100%
μ
100%
Parallel AC Bus — each panel independent
System output: ~86% (only 1 of 5 panels affected)
Deep Dive

Want to understand micro inverters vs string inverters in full detail?

Read guide
2

Common Shading Scenarios in Malaysia

These are the five most common shading culprits and their real performance impact.

String Inverter Loss
20-35%
of daily output
Micro Inverter Loss
5-10%
of daily output
Peak shadow hours: 7am–10am or 3pm–6pm

Tip: Trim trees annually or reposition panels. If trees can't be removed, micro inverters recover an estimated 10-25% more energy.

String Inverter Loss
25-45%
of daily output
Micro Inverter Loss
6-12%
of daily output
Peak shadow hours: 1pm–5pm (worst)

Tip: Permanent shading from buildings absolutely requires micro inverters or power optimizers. Do not install string-only on affected panels.

String Inverter Loss
10-20%
of daily output
Micro Inverter Loss
3-6%
of daily output
Peak shadow hours: 8am–11am

Tip: Relocate water tank or reposition panels away from its shadow path. Power optimizers on the 1-2 affected panels are cost-effective.

String Inverter Loss
15-30%
of daily output
Micro Inverter Loss
4-8%
of daily output
Peak shadow hours: 2pm–5pm

Tip: Separate upper and lower panels into different strings. Or use micro inverters — don't mix shaded lower panels with unshaded upper panels in one string.

String Inverter Loss
5-15%
of daily output
Micro Inverter Loss
2-5%
of daily output
Peak shadow hours: All day (cumulative)

Tip: Quarterly cleaning is ROI-positive in Malaysia. Anti-bird spikes on panel frames prevent perching. Monitor panel-level output to catch soiling early.

The choice between string and micro inverters is especially critical for shaded roofs. Read our complete inverter comparison guide to understand all trade-offs.

3

Shading Loss Calculator

Estimate your annual energy and financial loss from shading. See the difference between string inverter and micro inverter losses side-by-side.

Shading Loss Calculator

Estimate your annual loss and savings potential

10 kW
String Inverter Annual Loss
RM 672
1,512 kWh/yr lost
What you're currently losing
Micro Inverter Annual Loss
RM 140
315 kWh/yr lost
With micro inverters
Annual Savings with Micro Inverter
RM 532
1,197 kWh/yr recovered
Potential annual recovery

Estimates based on the site yield basis of 1,260 kWh per kWp per year (3.5 peak sun hours). Actual losses vary by shadow timing, panel orientation, and string configuration.

Want a full system sizing and savings estimate for your home?

Full Solar Calculator
4

Illustrative Scenarios — Not Trexon Projects

Three illustrative scenarios comparing estimated shading losses with string inverters and with micro inverters. Figures are estimates, not measured results.

Illustrative scenario 1 — not a Trexon project

Scenario 1: Large tree on a neighbour's land

Double-storey terrace — 10kW system, 22 panels

Shading Problem

Large rain tree, neighbors' land — shadow hits 4 panels 2pm–5pm daily

Before (String Inverter)
10,200 kWh
RM 4,590/yr
2,400 kWh lost to shading (19%)
After (Micro Inverter)
12,300 kWh
RM 5,535/yr
only 280 kWh lost (2.2%)
2,120 kWh/yr recovered
Energy recovered
RM 954/yr recovered
Annual savings recovered
Micro inverter cost:RM 9,200 (22 Hoymiles HMS units, market estimate)
About 9.6 years to recover the micro-inverter cost from the extra output (RM 9,200 ÷ RM 954/yr)

Micro inverters come out ahead when the shading source cannot be removed.

Illustrative scenario 2 — not a Trexon project

Scenario 2: New building next door

Semi-D bungalow — 16kW system, 36 panels

Shading Problem

New 4-storey condo under construction — will shade 8 west-facing panels permanently from 3pm

Before (String Inverter)
16,400 kWh
RM 7,380/yr
3,800 kWh lost (19%) — worsening yearly
After (Micro Inverter)
19,800 kWh
RM 8,910/yr
only 380 kWh lost (1.9%)
3,420 kWh/yr recovered
Energy recovered
RM 1,540/yr recovered
Annual savings recovered
Micro inverter cost:RM 14,800 for a full 36-unit micro-inverter conversion (illustrative market estimate); the owner upgraded only the 8 shaded panels first (8 micro-inverters)
Owner upgraded only 8 west-facing panels to micro first (RM 3,400). Payback about 2.2 years (RM 3,400 ÷ RM 1,540/yr).

Phased upgrade: micro only on shadow-affected panels = best ROI strategy.

Illustrative scenario 3 — not a Trexon project

Scenario 3: Chimney and neighbouring roof

Bungalow — 8kW system, 18 panels

Shading Problem

Owner's chimney casting 2-panel shadow 9am–12pm. Plus morning shadow from adjacent house roof.

Before (String Inverter)
8,600 kWh
RM 3,870/yr
1,450 kWh lost (14%)
After (Micro Inverter)
9,900 kWh
RM 4,455/yr
only 160 kWh lost (1.6%)
1,290 kWh/yr recovered
Energy recovered
RM 581/yr recovered
Annual savings recovered
Micro inverter cost:RM 7,200 (18 Hoymiles HMS units, market estimate)
About 12.4 years (RM 7,200 ÷ RM 581/yr) — marginal. Owner added panel monitoring value as secondary benefit.

Moderate shading: Tigo power optimizers (RM 2,400) on 4 affected panels gave 70% of the benefit at 33% of the cost.

All three scenarios assume Hoymiles HMS micro inverters, which Trexon does not stock (quoted per project). View Trexon's catalogue system packages.

5

Solutions for Shaded Roofs

Not all shading problems need the most expensive solution. Here’s how to match the fix to your specific situation.

Decision Matrix: Which Solution Is Right for You?

Tree Trimming / Panel Relocation

Upfront Cost (market estimate)RM 0 – 500
EffectivenessHigh (if feasible)
Best for: Trees you own and can trim. Panels that can be moved to unshaded area.

DC Power Optimizers

Upfront Cost (market estimate)RM 400–750 / panel
Effectiveness70-80% of micro inverter benefit
Best for: 1-4 panels affected by partial shade. Best with Huawei (Smart PV), Tigo, or SolarEdge.

Full Micro Inverter System

Upfront Cost (market estimate)RM 350–900 / panel
EffectivenessMaximum — panel-level independence
Best for: Heavy shading (5+ panels affected), multiple roof orientations, permanent building shadows.

Partial Micro Inverter Upgrade

Upfront Cost (market estimate)RM 350–900 × affected panels only
EffectivenessBest ROI for moderate shading
Best for: Isolate shaded panels onto micro inverters, keep clear panels on existing string.

Quick Decision Guide

1
Shading < 5% annual loss, tree you can trim
→ Trim the tree. No inverter upgrade needed.
2
1–4 panels partially shaded, < 3 hours/day
→ Power optimizers (Tigo/Huawei) on affected panels. Best ROI.
3
5+ panels shaded OR permanent building shadow
→ Full micro inverter system required (Hoymiles HMS is a market reference; not stocked by Trexon).
4
Multiple roof orientations + some shading
→ Micro inverters. Separate strings can't handle mixed orientation + shade.

Explore our residential solar packages; shading-specific equipment is quoted per site.

Residential Solutions
6

Malaysia 2026 Cost Comparison

Every option from “do nothing” to premium micro inverters. Market estimates for 2026; Trexon does not stock micro inverters or optimizers.

Option
Upfront Cost (market estimate)
Annual Loss (Residual)
10-Year Outcome
Do Nothing
Only viable if shading is minor (< 5% loss)
RM 0
RM 500–2,500/yr
Lose RM 5,000–25,000
Trim Trees Annually
Excellent ROI for trees on your land
RM 300–800/yr
RM 100–400/yr residual
Net positive if loss > RM 1,000/yr before trim
Best ROI
Power Optimizers (Tigo / Huawei)
Best cost-effectiveness for moderate shading
RM 1,600–6,000 (4-8 panels)
RM 50–200/yr residual
Positive ROI in 3–5 years
Full Micro Inverter (Hoymiles, market estimate)
Best for heavy/permanent shading. Also adds monitoring, safety, expandability.
RM 7,000–16,000 (full system)
RM 50–200/yr residual
Positive ROI in 7–10 years from energy recovery alone

A solar purchase can be spread with a card 0% instalment plan of up to 24 months, a bank loan from your own bank, or OKAPI rent-to-own for homes. Explore financing options.

7

Frequently Asked Questions

With a string inverter, a single shaded panel can reduce your entire string's output by 15-30%. With 2-3 panels affected (common with palm or mango trees), you lose 20-40% of daily production. Micro inverters reduce this to only 5-10% — only the shaded panel is affected, all others run at full power.
Yes. Partially shaded roofs are still viable in Malaysia. The key is choosing the right technology: micro inverters (Enphase, Hoymiles) or power optimizers (Tigo, SolarEdge) eliminate the string effect. You may also relocate panels to unshaded roof areas. Get a professional shading analysis before installation.
The Christmas light effect occurs when panels are wired in series (string inverter). Like old Christmas lights where one failed bulb darkens the whole string, one shaded panel chokes current for all other panels. A panel at 30% output drags the whole string toward 30%. Bypass diodes help partially but can't fully overcome this physics.
Micro inverters eliminate the string shading effect so each panel operates independently. A shaded panel only loses its own output — all other panels continue at full power. In heavy shading scenarios, micro inverter systems produce 15-25% more energy annually than string systems on the same roof.
Options range from free (trimming trees) to RM 400-750/panel for power optimizers, to a full micro inverter upgrade (Hoymiles: RM 350-550/panel, Enphase: RM 600-900/panel). For most Malaysian homes, power optimizers on 2-4 affected panels (RM 800-3,000 total) provide 80% of shading benefit at about half the cost of full micro inverters. All prices are market estimates, not Trexon prices.
Afternoon shading (12pm–5pm) is generally worse in Malaysia because peak solar irradiance is 10am–3pm. A shadow at 2pm during peak production causes more kWh loss than morning shading. Terrace houses with upper-floor shadows on lower panels typically suffer the worst peak-hour losses. Morning shading from eastern neighbors is less damaging as intensity is lower.

Related Guides

String vs Micro Inverter Malaysia 2026

Complete comparison: pricing, performance, brands, and who should choose what.

Read guide

Solar Savings Calculator

Get a personalized ROI estimate for your home, including shading adjustments.

Try calculator

Panel-Level Monitoring Guide

How micro inverter monitoring catches shading losses in real time.

Read guide
Free Quote

Is Your Roof’s Shade Silently Stealing Your Returns?

Send your address and roof photos for a free quote. We factor shading into the system design and show you how much energy (and ringgit) you’re losing — and whether micro inverters or power optimizers make financial sense for your roof.

Get a Free QuoteWhatsApp Us

SEDA-registered installer • free quote for Klang Valley, Selangor, KL, Penang & Johor

Palm tree shadows falling across part of a solar array