Solar geysers - Retro Fit Solar Geyser System
What is a Retro Fit Solar geyser System?
Basically, we take the Heat collector solar panels and attach them directly to your existing electrical geyser (Cobra, Kwikot, Franke etc). This has been a problem in the past, as there are not enough inlets and outlets in a normal geyser to accommodate Solar panels. However, certain valves have recently been developed by a few of the larger Plumbing supplies Manufacturers, which make Retro Fitting possible.
The Retro Fit system is just as effective as our ‘top of the range’ Split/Separated Evacuated Tube System, and is ideal for application in existing houses as well as New builds.. The other major advantage of the Retro Fit system is that it is a lot cheaper than buying a complete solar geyser system. The reasons for this are simple; firstly the solar tanks are very expensive, both in terms of cost and transport. Secondly, the installation costs come down dramatically. Effectively giving you a ‘top of the range’ system at the ‘bottom of the range’ price.
System
The Dako Power evacuated tube solar collector (number 1 in the schematic) converts solar radiation into heat and heats the relative small volume of water in the collectors heat exchange manifold. When the controller (number 2 in the schematic) detects that the water in the collector heat exchange manifold is 8 °C warmer than the water in the geyser the hot water circulation pump (number 3 in the schematic) is activated. The pump will force the warmer water from the collector into the geyser and replace it with cooler water from the geyser. When the heat exchanger manifold of the collector has dropped to below 4 °C above the geyser temperature the circulation pump is stopped. The solar collector will now heat this water to 8 °C above the geyser temperature and the controller will activate the circulation pump again. This cycle is continued all day long until the geyser has reached its user defined maximum permitted temperature or the sun has gone down.
The solar controller also takes control over the geyser element. If it should happen that there is not enough solar energy available to heat the geyser or all the hot water is used over night, the controller can activate the geysers electric element to boost the temperature. The controller allows the user to specify times and temperatures when the controller would be allowed to activate the geyser element. This function results in further electricity savings since the geyser’s element will never activate unless it is absolutely necessary.
This heating system is made up of either one or two heat collector solar panels (depending on the size of your existing geyser – there is a table below indicating the various solar panel sizes to geyser size), a circulating pump, a computer control system and 2 specialized valves.
| Panel Size | Heating Capacity |
| 18 Heat Pipes | 160 L |
| 36 Heat Pipes | 300 L |
The heat collector solar panels are made up of 18 heat pipes each, connected to a manifold. The absorption coefficient in the vacuum tubes is more than 0.94.
The circulating pump is a German made Wilo pump. It has a very low energy consumption level, low noise level and is extremely reliable and long lasting.
The computer controller is imported from Italy, and is extremely reliable and very user friendly.
Panel Specifications
Total Energy Consumption of 18 Tube Retro-fit Solar Geyser systems for 150litre geyser
The figures are based on a ‘worst case scenario’ situation, where all the hot water is used at the end of the day, and the electrical element is needed to heat the tank from 20ºC to 55ºC in the early hours of the morning (before the sun is up). Our calculations are formulated on the assumption that our 18 tube panel is used in conjunction with a 150Litre geyser with a 3 KW electrical element as back-up. We also referred to energy figures available on the Eskom website.
| Appliance | Wattage | Number of appliances | Running time (hours) per day | Total kWh Per 24hours |
| Wilo Pump | 67W | 1 | 3 | 0.2 kWh |
| Computer /Controller | 3W | 1 | 24 | 0.072 kWh |
| Element (2KW) | 3000W | 1 | 2 | 6 kWh |
| Total | 6.272 kWh |