Karavan, bahçe ve tekne için 12 V güneş panelleri

“12 V” refers to the battery voltage a panel is designed for. The actual panel voltage is higher – usually around 18 to 23 volts open circuit – so that the charge controller can fully charge the battery. A solar charge controller always belongs between panel and battery; it manages the end-of-charge voltage and charging profile to suit the battery (lead-acid, AGM, gel or LiFePO4).

An MPPT charge controller gets more out of the panel than a simple PWM controller, especially with changing irradiance and higher panel voltage. With several panels in series, you need one anyway, because the voltage is then above the battery voltage.

A simple back-of-the-envelope calculation helps you choose:

Rigid panels with aluminium frames are durable, well ventilated and can be securely fixed to the roof with spoilers or brackets. Flexible panels save weight and fit curved roofs, but age faster. The same considerations apply to garden sheds and boats; on boats, also make sure the connectors are saltwater-resistant. Larger panels of 36 V or more are suitable for 24 V systems or MPPT controllers with a higher input voltage.

Many listings bundle several output levels into one offer (“100W 200W 300W”) – the price shown then usually applies to the smallest variant. Check in the shop which version you're actually selecting. Also check whether a charge controller, cables or brackets are included. Some panels are offered with “0% VAT”; in Germany, the zero rate applies to systems on residential buildings, not automatically to every mobile use.