Image: Jwhferguson via Wikimedia CommonsWhile the batch solar water heater is the simplest of all solar water heaters, it does have its pros and cons. As it is prone to freezing, the system must be drained in winter months in colder climates. Its efficiency is also limited in cold weather and at night due to the significant loss of heat. In addition, a batch solar water heater is somewhat limited in size, so typically no more than four people can benefit from the system. As a batch solar water heater is also relatively heavy, it may require additional bracing when mounted on a roof. You may want to contact a professional solar installer for assistance or more details.
Because it is an “open loop” system where the potable water is heated directly, rust may become a problem. For this reason, it is best to use non-corrosive materials in building batch solar water heater systems. Using materials such as copper, brass, stainless steel, or plastic, along with the usual glass lining of a water tank, is recommended. Other issues can arise when using hard water. Hard water can leave calcium deposits and ruin an open loop system. If you plan to use hard water, it is better to go with a closed loop indrect system, which uses a separate fluid to transfer heat.
While a batch solar water heater system has its cons, it is simple to make, it is a passive system so it has no moving parts, and it is easy to maintain. A batch solar water heater is also among the cheapest solar water heaters available. Most other types of solar water heaters are more complicated and require the attention of a professional. If you are the sort who likes to keep an eye on the system, to understand how it works, and to resolve any maintenance issues independently, then a batch solar water heater could be for you.