A fixed panel is chosen by its voltage as much as by its watts
The best rigid solar panels for 2026
A rigid panel is mounted once and left there, so the specifications that matter are the electrical ones a controller has to live with and the mechanical ones a roof or a balcony has to carry. Peak wattage is again a laboratory figure; what a charge controller sees is the maximum power voltage and current, and what it must survive is the open-circuit voltage, which rises as the panel gets cold — the reason a string that works in July can overshoot a controller’s limit in January. The temperature coefficient, published as a percentage per degree, is the honest way to compare two panels in a hot climate: it says how much power is lost for every degree above 25 °C. Cell technology has moved on the shelf — PERC, half-cut cells, bifacial glass — and each publishes its own claim; what is comparable across them is watts per square metre and the temperature coefficient. Mechanically, the frame depth and the mounting holes decide what brackets fit, the glass thickness and the snow and wind load ratings decide where it can go, and the weight decides whether one person can lift it. Warranty terms are usually split in two — product and performance — and the second is a percentage of output after a stated number of years. We compare peak wattage, cell technology, voltages, temperature coefficient, frame and glass, dimensions and warranty terms.
