Specialists in Property Inspection, Renovation and Maintenance

Why Go Solar?

In a time when we need to reduce our dependence on fossil fuels solar energy does make a lot of sense. It is good for the planet, it can reduce our electricity bills and relieve the pressure on our straining electricity supplies.

1 Looking After The Environment

Electricity used in Bali is produced in East Java using coal from Kalimantan. It is a very inefficent process that causes major environmental damage in Kalimantan and pumps large quantities of carbon into the atmosphere.

2 The Rising Cost of Electricity and Free Hot Water

The national electricity provider, PLN, is struggling to balance its budget and has, over the past few years, progressively increased the cost of electricity. This is still not enough and the company still depends on government subsidies. We can only expect further increases in the cost of electricity in Bali.

3 Free Hot Water

Day by day the cost benefit of going solar is improving. A solar water heater can be expected to pay for itself in 6 years in Bali, considerably better than the payback period in Western countries.

4 Unreliable Electricity Supply

Very rapidly rising demand for electricity in Bali combined with a seriously compromised national electricity grid is creating huge difficulties for Indonesia's power supply. PLN is working hard to upgrade generation equipment that is both undercapacity and in poor condition but this will take time and money.

In the meantime we can only expect the present unreliablity of the power supply to continue with serious voltage fluctuations and frequent blackouts.

5 Overloading Your Household Power Supply

The more power you have to your home the higher your electricity bills are, some people are paying a lot of money. By managing the peak amount of power you use you can save a lot of money. An electric water heater usually takes a wopping 1,000 watts to heat water for only 2 bathrooms.

Because many of us are working within a peak power limit many of us have household supplies that will cut out when too many appliances are on a the same time.

By installing a solar water heater a significant load on our power supply can be removed removing stress on the system and improving the reliabilty of your household supply.

And if the power goes off we may not have light but at least we will have hot water.

Do They Work?

Yes of course they do, that is why WIKA are selling 1,000 a month and why there are so many solar water heaters available in Bali.

Solar water heaters heat water using the infra red portion of the light spectrum. Even on cloudy days there is enough power from the sun to heat our water.

Solar water heaters are designed to heat water to 65 degrees C (in western countries this is the legal maximum temperature under safety regulations). Solar water heaters can easily ahieve this temperature.

If those shower loving guests arrive and use all the hot water during the day you can always top it up using the inbuilt electric heater element.

How They Work - A simple but very effective concept.

A conventional solar water heater consist of a solar collector panel and a water tank. Water is supplied to the heater from the house cold water system and so is under pressure, this carries the water through the heater and on into the household hot water system.

The solar collector, a shallow box usually 2 metres high and 1 metre wide and about 8cms deep, is mounted on a roof facing the sun. The collector is usually connected to a horizontal water tank which lies across the top of the collector. Water from the tank runs down a pipe to the bottom of the collector panel, from here it flows up through a series of copper pipes which run up inside the collector panel collecting heat from the sun as it goes. At the top of the collector a return pipe carries the now heated water back into the water tank.

It is a very simply system which depends on one fundamental principle - hot water rises while cold water sinks. The pipe taking the water from the tank to the collector must come from the bottom of the tank where the water is coolest. From here the cold water sinks, flowing down the pipe to the bottom of the collector. Here it enters the collector and starts to heat up rising up the pipe in the collector panel and back to the tank. The pipe feeds the heated water into the top of the tank where the water is hottest.

A system that depends solely on water temperature differences for circulation is called a "passive" system. Sometimes the water tank is mounted away from, even below, the collector (you may want to hide it in the roof) in which case a small pump is used to circulate the water and this is called an "active" system.

Insulation is very important to maximise heat collection and retention. The collector panel has a glass cover allowing the suns rays to enter but preventing heat loss to the surrounding air. The water tank is insulated with a thick covering of cellular polyurethane foam to prevent heat loss particularly during the night.

This simple concept has had a number of modifications over the years:

• A thin copper collector plate is soldered to the snake of pipe inside the collector to increase the amount of heat being collected.
• Insulation is added beneath the collector plate to reduce heat loss from the underside of the plate.
• Special glass formulations have been developed to improve the transmission of the sun's heat into the collector panel.
• In colder climates the design is modified to separate the heat absorption system from the water to be heated so that antifreeze can be used to prevent freezing of the absorption fluid.
• A pressure relief valve is fitted to release pressure should the heater overheat.
• Electric heater elements are usually installed so that if the water is not hot enough it can be "topped up" using electrical heating.
• These days the copper plate and pipe have been replaced by much lower cost aluminium.

Solar hot water heaters usually heat to 60 degrees centigrade, any hotter than this is considered dangerous with a risk of scalding an unsuspecting bather.

The standard storage capacity of solar water heaters tends to be 160 litres to 180 litres, being larger than the standard 10 litres for electric heaters to allow for heat loss and night time useage this is ample for an average house.

These days solar water heater tanks are usually made from ordinary mild steel coated with vitreous enamel coating (the manufacturers call it glass lining). The tank has a sacrificial anode to prevent rusting and the anodes are designed to last about 8 years. Once the anode is gone the tank will probably rust out. A company from Perth used to manufacture heaters with stainless steel tanks, sadly they were bought out by one of the larger Australian manufacturers and the stainless steel was replaced by enamelled steel.

Over the years a number of variations of this conventional design have been tried. One of interest used high intensity parabolic reflectors which tracked the sun focussing its rays on a single straight pipe. These were very effective (in fact too effective and had to be designed to turn away from the sun if they got too hot) but were too complicated and could not compete with the simplicity of the standard design.

In more recent years a new development has been in the use of an array of evacuated tubes to replace the solar collector panel. The glass tubes are manufactured as two tubes one inside the other with an evacuated gap in between. A row of these tubes is pushed into the underside of the horizontal water tank. The water in the tank is free to run down inside the inner glass tube where it is heated by the sun and the hot water passes back up the tube and into the tank. The vacuum in the cavity between the glass tubes allows the sun's rays to pass into the tube while insulating the water from heat loss.

These heaters are popular and are usually markedly cheaper than the more conventional design. They do have a problem in that, because of the way they are designed, these heaters cannot take pressurised water so they require a ball valve to allow non pressurised water to enter the tank and they also need a small pump to repressurise the water and send it to showers and taps.

Solar water heaters, of course, have a basic drawback in that once the sun sets - no more heat (funny that) and most people want a hot shower in the morning. The larger tank capacity addresses this issue and users report that solar water heaters are highly effective.

In spite of this takeup of solar heater has been disappointing but is probably due to the fact that the better quality imported units (Rheem, Solarhart and now Ariston) are very expensive (Rp30 to Rp50 million), a substantial investment.

Cheaper units (such as WIKA) can cost anything from Rp11 to Rp20 million. A solar water heater will save between 2 and 3 million rupiah a year in water heating costs.