BUYERS GUIDE – SOLAR TECHNOLOGY

Solar energy is abundant, free and carbon-neutral without any downtime, outages or load-shedding for the next few Billion years.

It can also be harvested to replace 92%+ of our energy needs currently using carbon based energy sources.

Solar water heating absorbs the heat of the sun and is released through your taps and Solar radiation that is converted to electricity are the two technologies that are implemented.

Photo-Voltaic Electricity

olar Photo-Voltaic technology converts solar radiation (photons) into electricity by the photons knocking electrons from the atoms in the Solar cells and these flows through the cells, producing electricity in a direct current. This is used to charge the battery bank of a Solar Power station and an inverter then converts it to alternating current for our daily use. This technology is applied in three ways:

 

1. Grid-tied

The most economical way to use this technology because it works symbiotically with the national grid, using it in-lieu of a battery bank to subsidize normal consumption. Biggest shortfall is that you can’t access it during grid failure, outages or load-shedding and mostly used by larger consumers as a hedge against escalating cost and to reduce consumption.

 

2. Back-up

This application has an energy bank that supplies lighter consumers 24 hours a day, 7 days a week and provides basic but constant and reliable electricity, even during grid-failure, outages and Load-shedding while also feeding excess generated capacity back into the grid.

 

3. Off-grid

For reliable, constant electricity where there is no grid available or no grid connection is wanted. Has a bigger and higher energy bank rating to support full demand with generator support to load batteries during overcast conditions.

As the above graph clearly shows, payback varies depending on application. By combining the two solar technologies (See Soladi ”Load-shed buster” Super combo), payback can be achieved in as little as 48 - 60 months.

There are up to 5 components that has to be integrated with the above three systems.

1. Solar array

The solar panels are the collectors of the energy supply and require light, not heat to work. Each must be connected in “strings” or “blocks” to be integrated with the system electronics and the grid to be supplied with the energy. Positioning of installation is important and tracking arrays are used in low radiation areas.

2. Electronic suites

The electronics converts and regulates the collected energy for easy, everyday use by means of inverters, charge controllers, isolators and various components according to design parameters. The integration of these is critical to ensure the efficiency and longevity of the Power station and should be done by experts..

3. Energy bank

The one component where future developments could bring down the cost, currently lead- acid, gel, saturated matt, lithium-ion etc. is available with varying benefits. Lead-acid technology has a life expectancy of 10 - 13 years+ if properly specified, controlled and maintained and is the only tech we specify.

4. Installation and support

The design, installation and support/monitoring of the installation will ultimately determine its efficiency and return on investment. Soladi has a built in 10 or 20 Year maintenance plan on our standard designs to ensure this..

5. Support energy source

Where a grid is available or connected, this will provide energy to charge the batteries during overcast conditions or to supply additional energy on demand. With an off-grid system, a generator (diesel or petrol) or even a wind turbine could provide this.

Extensive research that is constantly upgraded with improvements ensures that the Soladi range of Power stations is, and will remain on the cutting edge of applied solar technology.

SOLAR WATER HEATING

A Solar Geyser will not only pay for itself but also provide substantial savings in energy spend over its life expectancy. With this technology two factors must be considered:

1. Efficiency
2. Life expectancy

Two technologies are available in both geysers and energy collectors.

1. Geysers

Direct systems heats the water directly in the collectors and in-direct systems use a heat transfer medium; GLYCOL or anti-freeze that circulates through the collectors and transfers absorbed heat to the water in the geyser through a heat exchanger. Direct systems are very robust and the original technology but in-direct systems can be also be used in frost prone or freezing conditions.

Calcification because of minerals and impurities in the water also affects the life and maintenance of direct systems so we use in-direct systems.

2. Collectors

The original “Flat Plate” panels are very durable and robust; it uses 6-10mm copper tubes encased in a “Hot-Box” behind low iron, solar glass while Evacuated tubes use a copper tube surrounded by a vacuum inside a glass or poly-carbonate tube as a heat extractor. Quality tube systems are 10 - 15% more efficient than flat plates, it was developed for hot water north of the arctic circle with its low radiation but is relatively fragile and isn’t suited to Africa’s harsh conditions. We simply enlarge our flat plate area commensurate with demand for a low maintenance, efficient system.

WHY A SOLADI GEYSER?

We market, support and maintain systems using latest generation “Double-Jacket” technology with an international footprint and enviable track record. Our flagship range with a 10 year guarantee and maintenance plan and a German developed system manufactured locally to SABS standards with a 5 year guarantee and maintenance plan.

1. Efficiency

Our “Double-Jacket” technology uses a double skin, filled with GLYCOL which is connected to the collectors to form a closed-loop system that ensures the warmest part of the geyser surrounds the water for a highly efficient optimization of captured heat. Heat loss during the night is less than 10% where other geysers lose up to 35%.

2. Life expectancy

All our systems come standard with a maintenance plan as part of the guarantee, either
5 or 10 Years. The weather proof outer skin encloses another 2 skins of 2mm high grade steel (Soladi 5) or 2 skins of 3mm mild steel (Soladi 10) that make up the “Double-Jacket” heat exchanger, same technology, different application but both extremely robust and efficient. Both inner skins are coated with a waterproof fused enamel lining to prevent rust and are tested and rated to operate at up to 6 BAR. A 200 L Soladi 5 weighs 44 Kgs and a Soladi 10,87 Kgs.

Soladi systems are the best in their fields, one an international import and others the best available locally with international standard technology.

Peace of mind is priceless and both offer this with our unique, inclusive maintenance plan.

DESIGN YOUR SOLAR GEYSER INSTALLATION

Now that you know what sort of system you want (Buyers Guide), what is the next step?

1. Sizing your system

The general rule-of-thumb is to provide 50 L of solar hot water per person per day to maximize the savings on your investment. 
Example: 4 people x 50 Litre’s = 200 Litre’s and 6 people x 50 Litre’s = 300 Litre’s.

There are exceptions though.

If you look at the Soladi combo’s for larger capacities, the technology benefits are compounded by utilizing it in tandem and reducing the energy demand of the electrical support system for a smaller volume during overcast weather.

Example: a 200 + 150 system will provide hot water for 7/8 people but only require electrical support during inclement weather for 200 of the 350 L capacity, an additional 40% saving on the already frugal electricity usage.

These combinations also puts the water supply through two solar cycle’s which provides higher temperatures and equates to extra supply capacity, a 300 + 200 system will provide for 12/13 people, an extra 2/3 free person capacity on the general rule-of-thumb.

2. Position your system

By viewing a satellite picture of your roof, the correct location with the shortest linkage can be identified. Ideally a solar water geyser should be installed within 45/50 degrees, either East or West from North and at a 12 - 45 degree angle to allow the heat transfer fluid to circulate freely without assistance of circulating pump.

Any installation outside these parameters loses efficiency and should be upgraded with enlarged panels; this is commonly known as “out-of-north” installs and will bring the efficiency up to standard.

The length of the linkage to the existing system is important and should be as short as possible to minimize energy and water loss. A rule-of-thumb is to keep it below 5 m and no more than 8 as you will wait an extra second for hot water for every 2 - 3 meters of linkage.

3. Identifying your system

By asking a few identifying questions as to why and for what purpose you are investing in this technology, your decision will easily crystallize.

Is the aesthetics of the system important?

The most efficient installation is on-roof with the geyser and panel together, this is called close-coupled but the geyser can be installed in the roof cavity providing it is still above the panel. This is called a split system.

4. Pumped systems

If neither of the above solutions can be fitted to your home, chances are that you could achieve similar results with the addition of a circulating pump.

At Soladi Africa we only consider this as a last resort, we believe in the KISS principle of keeping it simple.

5. Summary

Although not rocket science, careful consideration should be given to the installation of the correct solar geyser for your particular requirements.

One size doesn’t fit all...

Soladi Africa offers a free assessment and design service to ensure you get the best return on your investment with maximum savings on future energy spend.