— Number of collectors. Most modern solar collectors are sold one at a time, but some bundles include two or even three devices at once. Such kits are designed for extensive heating systems, for which one collector is not enough. Purchasing a set of several devices is convenient because they all have the same dimensions, performance and compatibility requirements with other system components. In addition, a set is often cheaper than the same number of collectors purchased separately.
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Water heater. The presence of a water heater in the collector's delivery set.
Usually, it is a storage water heater. The design of such a device is based on a tank of several tens of litres (often 100 or more). The water heated by the collector is stored in this tank until needed; the water heater usually has good thermal insulation, and the temperature of the water in it can be maintained at a constant level for quite a long time.
In general, a storage water heater is one of the most important components of a solar hot water system. However, many collectors allow operation with tankless water heaters when the water that has passed through the device is immediately supplied to the tap. However, this mode is not very convenient — in particular, because the water temperature is unstable, and besides, it is highly dependent on the weather. The tank water heater allows you to keep a guaranteed supply of water at a certain tempera
...ture. Such equipment can be sold separately, but buying a water heater at the same time as a collector is usually easier (no need to worry about compatibility), and often cheaper. — Photovoltaic module. The presence of a photovoltaic module in the design of the solar collector.
A photovoltaic module is a solar battery — an element that generates electricity from bright light. In modern solar collectors, such equipment is most often used to ensure electrical battery life: when the external power is turned off, the circulation pump and other components that require electricity are powered by the photovoltaic module, and the system remains operational. Of course, the quality of such power also depends on the intensity of sunlight, but modern technologies make it possible to create quite efficient and, at the same time, compact solar cells. Note that photovoltaic modules in such devices are usually made removable and may not be included in the delivery. The presence of such equipment in the kit should be clarified separately.
Another type of solar heater with photovoltaic modules is the so-called. hybrid models. They combine the actual collector and a large solar battery capable of generating electricity for external consumers. However, such devices are complex and expensive, and home solar power panels are much less common than solar water heating systems.
