A customer calling a solar installer almost always has one question in mind — “how many panels?” — and it is the wrong question. A photovoltaic installation is a chain: from the light captured by the panels to the socket where a refrigerator is plugged in, each link converts, stores, protects or distributes energy, and the chain is worth what its weakest link is worth. The installer’s trade consists of sizing that chain for precise uses, choosing components that deliver what they claim, fitting them by the rules and coming back to maintain them. So let us follow the current, from the panel to the socket.
Before the panel: the uses
Everything starts with a list: which appliances, what power each, how many hours a day, at what time of day, and how much autonomy the customer wants when the sun is missing. A refrigerator running at night, a pump that starts with a high inrush current, an iron used one hour a week, evening lighting: each weighs differently on the sizing. The installer records these uses, checks the sunshine and orientation of the site, the shade cast by a tree or a neighbouring building, the area and strength of the roof, whether the public grid is present and how reliable it is.
From that survey comes a written study: the power of the panels, the storage capacity, the power of the inverter, and the assumptions that led to these choices. An installer who proposes “a kit” without having recorded the uses sells a product; one who hands over a study sells a service — and it is the study the customer should demand before the estimate.
The panels: what they capture and what they do not
The panel turns light into direct current. Its output depends on its rated power, the actual sunshine, orientation and tilt, temperature, cleanliness and shading — a single shaded panel can drag down a whole string. The choice covers technology, manufacturer, power guarantee over time and the availability of after-sales service; the price per watt is only one criterion. The installer knows where their panels come from, what their datasheet says, and does not present rated power as a guaranteed output: a panel only produces its label value under laboratory conditions.
The charge controller and the inverter: the brain of the installation
Between the panels and the rest, the charge controller protects the batteries and optimises charging; the inverter turns direct current into alternating current usable by appliances and, in grid-connected installations, manages the exchange with the grid. These two pieces of equipment decide the safety and efficiency of the whole. An undersized inverter shuts down when the pump starts; a controller unsuited to the battery type destroys it within months. The installer chooses equipment compatible with each other, sets the parameters according to the batteries chosen, and explains to the customer what the indicator lights and alert messages mean.
The batteries: the most expensive and most fragile link
Storage is what provides electricity in the evening and on overcast days; it is also the costliest item and the one that wears out fastest. Lead-acid or lithium batteries, capacity, acceptable depth of discharge, number of cycles, operating temperature: each choice has consequences for lifespan and price, and the installer explains them rather than selling “the best”. They announce an expected lifespan under the planned conditions of use, never a guaranteed one: a battery discharged too deeply or installed in an overheated room will not last what its datasheet says.
Used batteries are hazardous waste. The Basel Convention provides technical guidelines for the environmentally sound management of used lead-acid batteries; the installer who replaces a bank knows where the old ones go, and does not leave them with the customer “to sell to whoever passes by”.
Protection, cabling, earthing
This is the invisible and most neglected part: cable sizes matched to the currents, overcurrent protection on the DC and AC sides, isolators allowing each part to be isolated, earthing, lightning protection where the site requires it, panel mountings able to withstand wind. An installation without protection works — until the day an undersized cable heats up in a false ceiling. The installer fits what good practice requires, even when the customer does not see it, and writes it on the estimate so the customer knows what they are paying for.
Fitting, commissioning and the file
Work on roofs, handling heavy panels, cabling under DC voltage, batteries able to deliver very high currents on a short circuit: a solar installation is a worksite with its risks, and the ILO recalls that a safe and healthy working environment is a fundamental right. Harnesses, secured ladders, insulated gloves, the connection order respected, every connection checked before energising: these gestures are not traded against a deadline.
Commissioning ends with measurements — voltage and current of each panel string, battery charge, inverter operation under load — and with a file handed to the customer: diagram, references and guarantees of each component, controller settings, instructions for use, what to do and not to do. The customer learns to read their installation: when it charges, when it discharges, when it alerts.
Where the site is connected to the public grid, commissioning has one more step: the installer checks that the installation does not feed current back into the grid without authorisation, which endangers the workers who intervene on the lines, and complies with the grid operator’s rules — declaration, meter, disconnection device — which vary from one country to another and which the installer does not invent.
Price, estimate and guarantees
The estimate separates the study, the components — one by one, with their reference —, the fitting, the protection, the cabling, the commissioning, and the maintenance contract when offered. It also separates the guarantees: the manufacturer’s on each component, with its conditions, and the installer’s on the fitting. An installer who promises “ten years of peace of mind” without saying who guarantees what promises what they cannot deliver; the one who writes down who answers for what, and whom to contact in case of failure, is the one who will be called back.
Maintenance: what an installation needs to last
Cleaning the panels, checking connections and mountings, checking the condition and charge of the batteries, reading the inverter logs, tightening what has moved: maintenance is modest but regular, and its absence explains most of the installations that “no longer work” after two years. The installer offers a contract, or at least a list of things the customer can do themselves and of signs that should make them call.
In the African context
For an off-grid household, a school, a health centre, an irrigation pump, an antenna, solar is not a supplement: it is the first electricity. That is the case for a large share of the installations fitted on the continent, to which are added everywhere backup installations against the cuts of an unstable public grid. The installer sizes systems on which the cold chain of a clinic or the lighting of a classroom depends, and the assessment of uses is all the more decisive because no one will come and make up for an error from the grid.
Product quality weighs just as much. The market is flooded with panels, batteries and controllers whose label does not match what they deliver; quality-assurance programmes such as VeraSol test off-grid solar products precisely so that products perform as advertised. The installer who buys from identified suppliers, checks the real power of a panel on delivery and refuses to fit a battery without a datasheet protects the customer from a purchase that will never produce what they paid for.
Maintenance and recycling, for their part, run into unevenly present channels: used lead-acid batteries, recycled informally, expose whole neighbourhoods to lead, and replacing an inverter may wait for an import. The installer who chooses repairable components, keeps a stock of parts and knows a battery take-back channel makes solar a sustainable energy in the most concrete sense.
The promises that betray a poor study
“You will never have a power cut again.” “The batteries last fifteen years.” “This kit suits every house.” “You don’t need protection, it costs for nothing.” “The price is the same for everyone.” Each of these sentences says that no survey of uses was made, that no datasheet was read, and that the chain will stop at its weakest link.
A solar installer is judged by what they ask before selling: the list of appliances, the hours of use, the autonomy wanted, the orientation of the roof. When those questions are asked, the number of panels comes by itself — and it is rarely the one the customer had in mind.