Solstore is a low cost eco friendly solar water heater cum storage system.

Solar water heaters are relatively low-tech systems, which have been unnecessarily enhanced with space age coatings, use expensive, scarce materials and consume considerable power in fabrication thereby increasing the cost.

Decades back Fortune magazine published a study showing that the total energy saved during the service life of such high end water heaters was less than the energy that went into producing the raw materials and manufacturing the finished product not to mention the cost of delivery and fuel used.

In the tropical countries power shortage is a perennial problem. However, electric water heaters continue to be sold in large numbers. Solar water heaters are becoming more popular.
Solstore uses low cost, low energy consuming raw materials, which are fabricated using processes using less energy. The design minimizes transportation bulk and reduces fuel consumption.

Being a low cost device Solstore is expected to be used widely. This reduces overload on the power grid and reduces recurring power costs to the user. The material can be recycled and has no harmful emissions during disposal.

The novelty of Solstore is in integrating the storage function with the heat collector in a single package. The main area of application is in domestic bath water heating in the tropical latitudes. At the low delivered cost it should find very wide spread use.

Solstore is made using UV stabilized, fabric reinforced, matte black poly olefin top sheeting. Simple low temperature welding is used to produce a pattern, which generates the required geometry on filling. It has an inlet and outlet that is also welded to the main structure. The design also incorporates a white bottom surface to minimize re-radiation losses. The device is not enclosed in a box with a glass top. Solar heat is directly absorbed by the fabric. Thermal siphoning ensures heating up of the water in the cylindrical multi-tubular structure. The outlet has an over pressure release valve to release excess pressure in case the water overheats forming steam.

Existing technology for welding flexible polymeric sheets will be used. A 30 US Gallon Solstore will need less than 10 kg of the fabric, which combined with the simple welding process, will drastically reduce costs. There is very little material waste. Very little power is used to produce the polymer and fabricate the collector. It is very light and can be shipped rolled up. The delivered cost to the consumer can be a small fraction of the cost of current systems.

There are some obvious limitations. Hot water will become available only after the sun has been shining on the device for some time. There is no extra insulation so that the water that has been heated till sun set may not retain all heat till the next day. However, the advantages outweigh these. Use may be limited to within 30 degree latitude.