A solar system that’s stopped performing rarely fails all at once — it’s usually one specific link in the chain (panel, controller, battery, or inverter) not doing its job, while the rest of the system works fine. That makes diagnosis very achievable once you know where to look. Here are the ten faults we see most often across Kenyan installations, including plenty we didn’t originally install.

Before You Call Anyone: A Few Quick Checks

Start by checking your inverter or charge controller’s display or status lights, if it has one — most units show an error code or status indicator that immediately narrows down whether the fault is with the panels, the battery, or the inverter itself. Next, physically inspect your panels for obvious shading — a tree branch, dust buildup, or even a shadow from a nearby structure at certain times of day can significantly cut output without any component actually being faulty.

Not sure what’s wrong, or need a proper diagnosis? Call or WhatsApp us on +254 741 163020 — describe the symptoms and we’ll often narrow down the likely cause before a technician even visits.

The 10 Most Common Solar System Faults

1. Dust or debris on the panels. This is the single most common cause of underperformance in Kenya, given how much dust accumulates on outdoor panels, particularly during dry seasons. Even a light, even layer of dust can meaningfully reduce output. Fix: clean panels with water and a soft brush or cloth, avoiding abrasive materials that could scratch the glass — this should be a regular maintenance task, not a one-time fix.

2. Partial shading. Unlike dust, which reduces output evenly, partial shading from a tree, building, or even a satellite dish can disproportionately cut a panel’s or string’s output, since shaded cells can affect the performance of unshaded cells on the same string depending on panel and system wiring. Fix: identify and, where possible, remove the shading source — overhanging branches are the most common and easiest to resolve.

3. Battery reaching end of life. Batteries lose capacity gradually, so a system that used to run your evening loads comfortably but now depletes faster than before is often pointing to battery degradation rather than a sudden fault. This is particularly common with gel/AGM batteries reaching their shorter typical lifespan, or any battery that’s been repeatedly deep-discharged beyond its recommended limits. Fix: a battery capacity test confirms whether replacement is needed.

4. Loose or corroded connections. Every connection point in a solar system — panel to controller, controller to battery, battery to inverter — is a potential weak point, and connections that were secure at installation can loosen or corrode over months of outdoor exposure and temperature cycling. Fix: a visual inspection of all accessible connection points, checking for corrosion, looseness, or damaged cabling, resolves a surprising number of “system not working” call-outs.

5. Charge controller fault. The charge controller (MPPT or PWM) regulates power flow from panels to battery, and a fault here can leave your battery undercharged even with panels producing normally. Fix: most controllers display an error code or status light indicating the specific fault — this genuinely helps narrow diagnosis quickly if you can read and report it when contacting us.

6. Inverter not switching to battery power during an outage. For hybrid systems, this is one of the more alarming faults since it defeats the entire purpose of battery backup — the system may be charging fine but failing to actually switch over and power your loads when grid power drops. Fix: this typically points to an inverter configuration or fault issue rather than the battery itself, and needs a professional diagnosis to isolate correctly.

7. Undersized system for actual load. Sometimes there’s no fault at all — the system is performing exactly as designed, but consumption has grown since installation (a new appliance, more frequent use) beyond what the original system was sized for. Fix: this isn’t a repair but a genuine capacity conversation — worth an honest assessment of whether your system needs expanding rather than repeatedly troubleshooting normal behaviour under an outgrown load.

8. Inverter overheating or thermal shutdown. Inverters generate heat during operation, and units installed in poorly ventilated spaces, or pushed beyond their rated continuous load, can shut down temporarily to protect internal components. Fix: check installation location for adequate airflow, and confirm your actual load isn’t regularly exceeding the inverter’s rated capacity.

9. Damaged or degraded panel cells. Micro-cracks, hotspots, or cell degradation — more common on unbranded or lower-quality panels, but possible on any panel after years of thermal cycling and weather exposure — reduce a specific panel’s output without necessarily being visible to the naked eye. Fix: a proper output test on individual panels or strings identifies underperforming units that visual inspection alone would miss.

10. Incorrect system settings after a firmware update or reset. Modern hybrid inverters have configurable settings (charging priority, battery type profile, grid-tie parameters) that occasionally get reset or misconfigured — after a firmware update, a power event, or manual adjustment — leading to behaviour that looks like a hardware fault but is actually a settings issue. Fix: verifying and correcting inverter settings is usually a quick fix once identified, but does need someone familiar with your specific inverter brand and model.

DIY Fix or Call a Professional?

Panel cleaning, checking for obvious shading, and a basic visual inspection of accessible connections are all genuinely manageable yourself. Anything involving the charge controller, inverter settings, battery diagnostics, or suspected panel cell damage is worth having professionally assessed — modern hybrid systems have enough configuration complexity that a wrong DIY adjustment can create a new problem while trying to fix the original one.

If you’re not sure which category your fault falls into, describe the symptoms first. Call or WhatsApp +254 741 163020 — we can often narrow down the likely cause before a technician arrives, speeding up the actual repair.

We Service Systems We Didn’t Originally Install

If your solar system was installed by another company and isn’t performing as it should — or that installer is difficult to reach for support — our technicians diagnose and repair systems regardless of who installed them originally, including identifying whether previously installed equipment is genuine, correctly sized, or simply underperforming due to a fixable fault.

Preventing These Faults in the First Place

Most of the ten faults above are preventable with a simple, low-effort maintenance routine: clean panels every few months, or more often in dusty areas; check accessible connections and cabling a couple of times a year; monitor battery performance trends over time rather than only noticing a problem once it’s severe; and have your system professionally serviced periodically, particularly for anything beyond a basic residential setup.

Frequently Asked Questions

Why has my system’s performance dropped gradually rather than failed suddenly? Gradual decline usually points to dust accumulation, battery degradation, or growing shade from vegetation — all things that develop slowly rather than appearing as a sudden fault.

My battery charges during the day but drains very fast at night — why? This often points to battery capacity loss (particularly if the battery is several years old) or a load that’s grown beyond what the battery was originally sized to cover overnight.

Can dust really make a meaningful difference to panel output? Yes — in dusty conditions, unclean panels can lose a meaningful percentage of their potential output, which is why regular cleaning is one of the simplest, highest-value maintenance tasks available.

How much does a typical solar system repair cost? It depends entirely on the fault — a cleaning or connection fix costs very little, while a battery or inverter replacement is a larger expense. We provide a clear diagnosis and quote before any repair work begins.

Get a Diagnostic Visit

Book a diagnostic visit: Call or WhatsApp +254 741 163020 or email info@happysolar.co.ke Browse our full range: Happy Solar Systems shop

We diagnose and repair all major solar system brands, regardless of who installed them — with a clear, honest assessment before any work begins.