Solar System Underperforming
Low Output: Causes, Checks & Who to Call (2026)

What "underperforming" means for your system

Before hunting for a fault, know roughly what the system should make. ClickBina's solar panel cost guide gives typical monthly generation for common home system sizes. Real output swings with the weather and the season, so compare like with like: this month against the same month last year, or a clear week against a clear week.

A roof that faces north, a steep shaded valley or an array split across several roof faces will sit at the lower end or below it. The same guide notes that north-facing surfaces generate less in Malaysia. What matters for diagnosis is a change from your own normal, not a gap against a brochure figure.

Read the monitoring app first

Most systems come with app-based monitoring, and it is the best diagnostic tool you have. ClickBina's solar cleaning and maintenance guide explains how to read it: a slow decline that recovers after heavy rain points to dirt, while a sudden drop, or one section producing far less than the rest, points to a fault or shading and is a job for the installer, not a cleaner.

• Look at the daily curve. A smooth hump on a clear day is healthy. A curve with a flat top, a dip at the same hour every day, or a line that drops to zero in the middle of the day tells you something specific.
• Look at the error log. Inverters record trips and faults with a time stamp.
• Look at strings or panels separately if the app shows them. One weak string is a local problem.
• Keep a simple record of monthly totals so a slow drift is visible.

Symptom and likely cause

Dirt, droppings and haze

A thin even layer of dust lowers output a little across the whole panel. A single bird dropping or a leaf can shade part of a cell and pull down the output of the whole string of cells it belongs to, as the cleaning guide explains. Rain helps, but it does not clean off droppings or the greasy film left after haze.

The solar cost guide suggests rinsing panels clean once or twice a year. Low-tilt panels, roofs near highways or construction and roofs under trees need it more often. The cleaning guide sets out the safe method and warns against pressure washers and standing on panels.

New shade and the string effect

Shade is the cause people miss because it creeps in. A tree grows, a neighbour adds a storey, a new water tank or aerial goes up. Most home systems use a string inverter, and ClickBina's inverter guide explains the weakness: a string acts like a single larger panel limited by its poorest performer, so shade on one panel pulls the whole string down.

Watch the daily curve for a dip at the same hour. If the shade is from your own tree, trimming it is the cheapest fix you will find. If it is permanent, the inverter guide explains that microinverters or optimisers limit the loss to the shaded panels; that is a design change to discuss with the installer.

Inverter faults, trips and heat

The inverter converts the panels' DC output into AC for the house and the grid, and the solar cost guide calls it the most likely component to fail. Plan to replace it once over a panel life of around 25 years. Signs of an inverter problem are an error code, a unit that restarts repeatedly, or output that stops while the sun is out.

Location matters. The inverter guide notes that a wall-mounted inverter should sit somewhere shaded and ventilated, because heat shortens the life of electronics; a unit in full afternoon sun is a poor choice. Do not open the inverter or the DC isolators yourself. The panels produce electricity whenever light reaches them, so the DC side is live in daylight.

No output during a power cut is normal

If the system stops every time the grid goes off, nothing is wrong. The inverter guide explains that grid-tie inverters are designed to shut down automatically when the utility supply is lost, for safety, and do not provide backup power during outages. Only a hybrid system designed for backup keeps supplying the house. Frequent short trips on a stable grid are a different matter and worth raising with the installer.

Cables, connectors and animals

The cleaning guide lists what a proper maintenance visit checks: inverter status and error history, cables, connectors and cable ties that sun and animals damage over time, mounting rails and clamps, gutters below the panels, signs of nesting, and new shading. Pigeons nesting under the array bring droppings and chewed cables. A single failed connector can take a whole string offline.

Ask the maintenance visit to state in writing what it checked and what it found. That record is what separates a real fault from guesswork.

When the bill, not the system, is the problem

Many "underperforming" calls turn out to be billing questions. Under net energy metering, as the solar cost guide describes, the panels power the home first and only the surplus is exported and credited. If the family added an aircon, started working from home or charges a car, the bill rises even with normal generation. Compare the app's generation with last year before assuming a fault.

Export schemes change. ClickBina's solar leasing guide notes that SEDA's Solar ATAP is the continuation of the NEM programme, which concluded at the end of June 2025; confirm the terms of your own scheme with your installer or the energy authority if the way credits appear on the bill has changed.

Who to call

Panels, inverter and wiring are the solar installer's work. ClickBina's solar installer guide explains how to check that a company appears in SEDA's RPVSP directory of PV service providers and where to complain if something goes wrong. It also notes that the homeowner remains responsible for the safe operation and maintenance of the installation up to the interconnection point, which is one more reason to keep the maintenance records.

The roof is a separate trade. A leak that started after the panels went in is almost always at a mounting penetration; ClickBina's solar roof leak guide explains how to tell and who to call.

Related costs

ClickBina does not publish solar repair prices. These are the related figures on ClickBina's solar guides (indicative 2026, Klang Valley), useful for judging a replacement against a repair.

A drop in output alone is not a roof problem. Keep the two questions apart: the installer for generation, a roofer for water.

How ClickBina can help

Solar installation and repair are not among ClickBina's own trades. Where the problem is on the roof, such as a leak around the mounts, birds under the array or a roof that needs work while the panels are there, WhatsApp us your job details for a quote: the roof type, the system size and what has changed. Roof leaks are assessed through ClickBina's leak detection at RM300 – RM800 per visit, charged separately from repairs. ClickBina is an experienced KL & Selangor contractor for whole-house refurbishment and trade coordination. We reply within the hour, and the price we agree is a flat price with no hidden charges. A site visit is RM150, waived if you go ahead.

Sources & methodology

• ClickBina solar panel cost guide — typical monthly generation, system prices, net metering, north-facing roofs and the inverter as the part most likely to fail.
• ClickBina solar cleaning and maintenance guide — reading the app, dirt and droppings, maintenance check items and related prices.
• ClickBina inverter guide — string behaviour under shade, inverter location, grid-tie shutdown.
• ClickBina solar installer guide — SEDA's RPVSP directory and owner responsibilities; solar leasing guide — Solar ATAP as the continuation of NEM.

How we estimated prices: every RM figure on this page is quoted unchanged from the ClickBina guides named above; they are indicative Klang Valley ranges for 2026, not fixed rates.