CURRENT PROJECT - 2009
SOLAR WATER HEATING SYSTEM

Below is MY learnings and views.
It does not represent the views of professionals.


 

 

Read "After sales service:" Scroll down


I had to choose between a solar panel- and vacuumed tube system.

I wanted low maintenance and from what knowledge I could gain, the vacuumed tube system depends on the quality of the vacuum inside these tubes. As the tubes age, it is only natural that the vacuum will become less. This will in turn affect their heating ability. Solar panels on the other hand, can last for longer than 20 years and requires very little maintenance.

By installing a valve the panels can be flushed whenever (every 3 to 5 years) needed to. Cleaning the surface is not a difficult job (single storey home).

The angle of your solar panels

This is very important as your panels needs to be mounted onto a frame. The frame must accommodate the angle of the panels. Obtain the latitude, where the solar system will be installed. The latitude reading will indicate the best angle for your solar panels to be placed at, to give optimum performance.

If your latitude is a negative value, you want to face your solar panels North.
If your latitude is a positive value, orientate your solar panels South.

You can be 10 to 15 degrees to either side of this optimum setting without losing much power or efficiency from your panels. You can also set your solar panel for optimum performance in summer and winter. In summertime, the solar panel should be at a lower angle. (I will rather go for a fixed angle, as moving parts points to weaknesses in the system.)

This is because the sun is higher over head in summer. In wintertime, the sun moves across the sky at a lower angle.

For the Northern hemisphere, your panels should be facing as close to South as possible.
In the Southern hemisphere, you want to orientate your solar panels to the North.

This website address will help you to determine the latitude:  http://solartradingpost.com/solar-angle-calculators.html

My optimum setting is 34 degrees, but the panels are installed at 40 degrees. Thus optimum performance in winter.

The solar geyser.

For myself, I did not want a time bomb (pressurized geyser) situated inside my home. For that reason I wanted a close coupled system (panels and geyser on top of the roof) where water could not damage the interior of my home, if the geyser started to leak or if it burst. I also wanted a geyser that could match my gravity feed, (copper inside) geyser for reliability and low maintenance. I did not want to change an anode on a yearly basis. I found a Solartherm geyser, with a 10-year warranty. The inside consists of a pex [some kind of flexible pvc material] and the outer of galvanized steel. There are solar geysers for direct (geyser and panels outside) and indirect (geyser inside and panels outside) systems.

The geyser size is very important. Not for the short term but when you need to sell your house. Solar water heating will become a very attractive feature soon. I had a 150 liter geyser (old system). The solar system will have a 200 liter geyser with two panels.  

Piping

I always believed in copper. It is durabile and proven itself over the years. The rule: If the plumbing system is copper, stick to copper. To go for the cheaper option by using other material might cost you dearly in the long run. Water damage can be very expensive, and insurance companies will always try to find a reason to downsize a claim.

Pressurizing the water feed.

An always safe rule for old houses: Never pressurize (400kpa) your main water feed. Especially older houses, as they were not designed for a high pressure. As the piping is old, do not impose more load onto the system.

This is what my installer came up with. He inserted a 100kpa valve near the inlet of the geyser. Although the geyser could handle 400kpa with ease, the 100kpa water pressure, and say the 50kpa gravity drop from geyser to floor level plus the heated water causing some pressure in the geyser can amount to 200kpa for the hot water feed into the house. As the pressure should be way below 400kpa, the limited contraction and expansion should increase the lifespan of the geyser.  

Installation requirements.

I needed my Geyserwiser to be incorporated into this solar heating system. The Geyserwise will show me the temperature of the water inside the geyser at any time. I can also leave all my setting as it was with my old system. The Geyserwise functions on two inputs: 1) Preset temperature and 2) Preset time periods. If the water temperature is more than the maximum setting on the Geyserwise (55 DegC), the element will not switch on. If it is overcast, the Geyserwise will operate according to the preset time periods until it reaches the preset temperature.

2009: Only time will tell if I made the correct choices regarding the quality and if the system is efficient to deliver. At lease a full year cycle is needed to evaluate this system.


2011: After installation and being in operation for 2,5 years: Yes, I made the correct choices averaging an electricity usage of 17 units per day ( 515 units per month = R540pm).

But the credit must also go to the installer / advisor, Anwaar.
Anwaar @ Cell: 079 614 0917 > e-mail:
anwarnold@gmail.com.
He got many years of experience and deliver excellent quality workmanship.

Saturday, 3 October 2009 the system was activated @ 13h00. By 14:45 the temperature was 47 degrees Celcius.
Sunday, 4 October 2009 the water temperature was 58 degrees Celcius.
Monday, 5 October 2009 [Overcast] the temperature came to 48 degrees Celcius.

The complete system (inclusive of installation) ended up costing R16 912.00
No Eskom rebate involved as no submission was done for this system.
I was quoted (another company) R 23 710 minus R3 900 Eskom rebate =R19 810 for the same system but a Kwikot geyser.

Saving Summary: With the old gravity feed 150 liter geyser = Total household unit usage: 29 units per day
After adding the Geyserwise to the system = Total household unit usage dropped to 23 units per day
Replacing the gravity feed geyser with the solar geyser and connect the Geyserwise to it = Total household unit usage dropped to 16 units per day. (31 day trend).
See graphs below - 3 Oct. to 3 Nov. 2009

After sales service: February 2010: One of the solar panels had a small seam leak (water vapor appeared on the inner side of the glass at the bottom corners). I contacted Anwar and he informed me that the panel need to be replaced. We agreed to a date and time. Anwaar suggested that the replacement work is best performed late afternoon, as the water heating process would be completed by then. Anwaar was on time and within 20 minutes the panel was replaced. Because of his initial installation, which included extra cutoff valves on either side of the panel feeds, the replacement took place without draining the heated water in the geyser.

My customer satisfaction level for his service and promptness... more than 100%.

Some more data / information (Region = Western Cape / Cape Town):
Please note: Electricity Units Used = COMPLETE HOUSEHOLD USAGE

I managed to keep a record of my electricity usage (20h00) and the geyser water temperature (max 16h00) every day. Before the Geyserwise my electricity units used per month, averaged between 28 and 32 (Current price @ R1.06c per unit) = R922 per month)

Orange colour bar 22 units average per day (Feb 2008 to Sep 2009)
usage with Geyserwise in operation but WITHOUT the Solar system (Current price @ R1.06c per unit = R742 per month)

Orange colour bar 17 units average per day (Oct 2009 to date)
usage with Geyserwise AND  the Solar system in operation (Current price @ R1.06c per unit = R542 per month)

Blue line = The maximum water temperature taken at 16h00 every day. (On the graph the ave temp per month)

I shall recommend the following to reduce your electricity consumption:
Install a Geyserwise device (currently "2013" R1300 once off)

The advantages:
Good return on investment with cost recovery within 3 to 4 months (ROI)
The geyser electricity consumption can be controlled by setting the on/off periods and maximum temperature.

Facts
Before I installed the Geyserwise device:
I used an average of 29 units per day
= R922.00 per month making use of R1.06 per unit

After I installed the Geyserwise device:
I used an average of 22 units per day
= R700.00 per month making use of R1.06 per unit

After I installed the Geyserwise device AND Solar panels / geyser:
I used an average of 17 units per day
= R540.00 per month making use of R1.06 per unit

I paid R800 for my Geyserwise device and recover the cost within a couple of months
The solar system ended up costing R16,000. It will take me around five to six years to recover the cost of the solar system. With the rapid increase in unit cost, the five years dropped to just under 34 months.