Despite South Africa’s plentiful supply of solar irradiation, the cheap cost of coal-fired power, compared with relatively expensive renewable-energy technologies, has meant that the uptake of these technologies is slow. To date, there has been little incentive to invest in capital-intensive solar systems. However, there are certain South Africans who see solar power as the way forward, and have taken the leap to power their homes and businesses from this source.
Some have made the move for research reasons, others to be independent of utility power, but most believe that environmental and life-cycle operational cost benefits will eventually flow. In this cover story, Engineering News takes a look at one agency’s ambitions to manufacture modular renewable-energy integrated afford- able housing; a university’s research into grid-free living; a newly built, completely grid-free home in Gauteng; and a grid-connected Johannesburg suburban home that is supplementing supply with its own nongrid renew-able energy.
Modular and Self-Sufficient
The South African National Energy Research Institute (Saneri) says that opportunity exists in South Africa to supply manufactured houses with a factory-fitted sustainable energy supply.
Saneri CEO Kevin Nassiep says that the intention would be to manufacture, where practical, and factory-fit these renewable- energy products onto the manufactured house. The houses would be manufactured in sections, which would be transported to a prepared site for assembly.
The proposal entails a 55-m2 manufactured home, with energy-efficient building materials, including composite cement insulated walls and an insulated ceiling, which would lower artificial heating and cooling requirements.
The house would have two bedrooms, a lounge, a kitchen and a bathroom, and facilities would include a bath or shower and a toilet, a basin, a sink, shelving, a geyser and a gas burner, energy efficient lighting and plug points – all utilities would be connected.
This grid-free home would include a biogas digestor to supplement liquefied petroleum gas (LPG) used for cooking with a gas hob, which would be provided as part of the basic house design.
Thin-film solar panels would be placed on a stainless-steel section of the roof to provide electricity for basic needs and appliances, and a solar water heater would be fitted to provide all hot water needs.
“We are planning to build a prototype early next year, but it depends on a pilot production facility, since it is a manufacturing project, not construction,” Nassiep explains.
He notes that the idea originated from a company, Greville Wood Designs, in the 1980s – the idea was piloted in the Port Elizabeth area some 14 years ago and the house is still standing. “It just needs some tender loving care because of neglect,” he notes.
He explains that the idea is receiving signifi- cant interest from various stakeholder groups, such as the African National Congress Women’s League. Since the house is energy self-sufficient, it can be assembled quite easily in remote, rural areas where people do not have ready access to clean, affordable energy sources.
“We are keen to work with interested parties, such as the South African Academy of Engineering, Anglo American, Eskom, the Council for Scientific and Industrial Research, the Central Energy Fund and others, to form a consortium of parties to help drive the idea,” says Nassiep.
The principle is for the community to own the manufacturing plants eventually. “I see some merit in initial private-sector equity partnership to ensure adherence to good governance and sound business principles,” he adds.
Some 200 manufacturing plants are envisaged countrywide, and interest has been expressed from abroad, including Tanzania and India. Saneri will stay involved in terms of improved design, and will co-own and fund the pilot plant, as well as assuming respons-ibility for training of staff and trainers.
Nassiep points out that homes for the Breaking New Ground Programme could be designed like this in future, and even first-time home buyers could benefit.
There is a design for a middle-class house that comprises two of the smaller-style houses, and Standard Bank has expressed an interest in this type of housing.
Nassiep also adds that Absa is interested in seeing a new prototype demonstrated, since the bank is currently running a competition in the Western Cape to determine suitable alternative building materials for low-cost housing. This house will be separate to the project but still reviewed by Absa.
In March this year, Engineering News reported on an energy efficient building-integrated photovoltaic (BIPV) house that was constructed at the University of Fort Hare’s Alice campus, in the Eastern Cape, and is being monitored by PhD student Sosten Ziuku.
A competition among schools in the area to name the house and create awareness of renewable energy and energy efficiency saw pupils at Alice Primary School win the prize of four energy efficient computers, after their suggestion of LangalinaMandla, meaning ‘powered by the sun’ was adopted.
PV panels are mounted on the north-facing roof and replace conventional roofing material, and the PV solar system has a maximum power output of 3 800 W. Energy efficient electrical appliances are also used in the house, and a 200-ℓ solar water heater is used to meet all the hot water requirements.
Ziuku explains that data from the month of June showed that the net income – factoring in the avoided cost of utility electricity, plus a feed-in rebate at the proposed R 4,49/kWh – was calculated to be R1 524,88.
“This amount is very attractive and reduces the payback period of the solar house significantly. A further advantage is that the design and technologies used can be replicated anywhere in South Africa and should particularly be considered on a smaller scale for low-cost housing,” says Ziuku.
He tells Engineering News that one student occupied the house in March, and was satisfied with the electrical system and hot water supply. From May to August 31, two postgraduate students occupied the house, and a university staff member is expected to move into the house this month, as ceiling and insulation fittings were added in September.
“Feedback from the occupants indicates that hot water was not always available in winter, particularly in July. We recorded winter minimum ambient temperatures below 0 ºC, and this resulted in geyser storage and pipe standing losses. Geyser blankets and pipe insulation are necessary interventions to reduce standby losses,” explains Ziuku.
He says that the electrical energy supply from the 3,8-kW system is proving more than enough to power the household loads and the battery bank. Data from the charge controller shows that the PV modules operate at maximum capacity for, at most, four hours of the day, after which they only supply electrical power when required.
The occupants were generally satisfied with the electrical power supplied by the BIPV system. On isolated occasions, notes Ziuku, the battery bank would discharge most of its storage after extravagant use of energy by the occupants, especially over weekends.“
Indoor and outdoor temperature measurements show that the house has a thermal efficiency of 75% in winter. This indicates that the indoor environment remains within the temperature comfort range of 16 ºC to 28 ºC for 75% of the day. We expect that the thermal efficiency will surpass the 80% mark, as recommended by the ISO standard 7730, after application of a ‘nansulate’ insulation coating and ceiling,” adds Ziuku.
He highlights that important lessons have been learned from the BIPV house. He notes that occupants must be familiar with energy efficiency measures. As a result, a users’ guide is being drafted for green building owners and inhabitants. Also critical is user participation in management of the stored energy, especially overnight.
“Users need to be informed of the solar technology capabilities and limitations so that they can provide the necessary cooperation for long-term system operation,” he stresses.
Blisfully Grid Free
“We didn’t want to change our lifestyle, just the energy source,” explains Netshield CEO Inus Dreckmeyr, with reference to his family’s decision to live in a home powered completely by solar power and free of any connection to the Eskom electricity grid.
What Dreckmeyr calls “a standard family home” is a 1 000-m2 house, just outside Pretoria, in Silverlakes, equipped with standard appliances, and with seven people living off the power source. At this stage, the house is purely powered by solar PV panels, with gas for heating and cooking.
Dreckmeyr is investigating adding a wind turbine to generate power, as well as a bio-gas digester powered by chicken manure to produce natural gas, to substitute the LPG for the heating and cooking requirements.
The solar system has been operational at the house for 18 months, and came at a capital cost of some R320 000. Dreckmeyr adds that the cost of connecting the home to the electricity grid would have been in the region of R170 000.
“The initial cost is not such an issue any more, and a shift in attitudes is emerging. If the incentives and subsidies came through, people would be more serious about implementing these systems,” states Dreckmeyr.
He admits that the initial layout is costly, but adds: “If you start from scratch and integrate in the planning phase, you realise there are basic costs at any level; to connect to the grid also costs money. So, if you plan right from the start, use solar PVs and wind, you can use some of the initial layout for grid connection towards renewable energy.”
Questioned about the most difficult aspect of the system, Dreckmeyr indicates that educating the family to be consciously sparing with electricity has been a challenge. “Instilling behavioural changes is difficult when a child wants to play computer games, listen to the radio and watch television all at the same time, he quips.
Dreckmeyr’s company, Netshield, which is a division of Comztek, a JSE-listed Mustek subsidiary, is working on a device to assist in managing energy.
“We produce a workable solution from an idea,” says Netshield account manager Johan van Heerden. Netshield has done about R600 000 worth of research and monitoring on the system linked to Dreckmeyr’s home, and is putting the “final tweaks” on the monitoring system prototype, which is eventually intended to work with an interface on a cellphone as one of the options.
Dreckmeyr says that, to attend to the management of the systems, one needs to under- stand the energy use. “You must understand your consumption before you can complement it with renewable energy or divert to other sources.
“Independence of the grid is a ‘nice-to-have’ today, but future electricity costs are unknown, so independence from that variance of costs, and reducing the carbon dioxide impression, were at the core of the decision to use renewable energy,” adds Dreckmeyr.
Netshield business development and market- ing manager Daniel Ngwepe points out that interest in renewable energy varies between electricity power cuts and load-shedding by the utility. “Eskom power is great when it’s available, but it’s not always available; and if variation billing is introduced, we will pay more in peak hours,” he says, and adds that a national effort is required to drive renewable energy forward.
The Power Company director Jon Adams added renewable energy solutions to his grid-connected home in Johannesburg’s northern suburbs some 18 months ago. There are 36 Sharp 80-W thin film solar panels, and two collectors for solar water heating, with a 48-V dc battery pack. LPG provides the fuel for cooking.
The capital cost of the complete conversion was in the region of R320 000, and Adams points out that, because the system is modular, it can be built up over time. He also tells Engineering News that the electricity bill for the house has reduced by between 75% and 80%.
Since installed, solar generation has amounted to over 3 625 kWh, LPG has displaced 2 264 kWh of electricity, and solar water heaters have displaced a further 1 456 kWh of electricity. In terms of climate savings (according to Eskom data for August 2008), Adams explains that the system displaced 3 297 kg of coal; 8 480 ℓ of water used in power generation; 948 kg of ash; 5 889 kg of carbon dioxide; 51,2 kg of sulphuric oxide; and 25,9 kg of nitrogen oxide.
Adams explains that, if the family could sell the excess energy generated by the system back into the national electricity grid, as is proposed by many small-scale solar energy producers under the renewable-energy feed-in tariff (Refit), it would allow for income generation.
He says it would have to be done as in Germany, where the total energy would be counted as displaced Eskom energy and bought back under Refit. If the tariff was about R5/kWh, as was proposed for solar power under Refit, Adams would have made about R40 000 from his 3-kW/h system. The system could thus pay for itself in about eight years.
This would certainly incentivise home- owners to invest in renewable energy as, apart from lowering operating costs and having a lesser environmental impact, a favourable return on investment could be made.
Again, the biggest challenge in implement- ing the solar system has been educating occupants of the home about energy use and changing certain energy-intensive habits, and Adams says that the family has become more energy efficient.
“There is a need to change the perception of solar power as a second-grade power,” says Adams, noting that, if the houses in Sandton use solar power, there will be more buy-in from rural communities. Here the benefits of extending renewable energy to areas where the national electricity grid does not yet reach would significantly improve the standard of living of many people.
“Being energy independent is great, and the system has significantly improved my life, yes – because all the fridges run off the solar system, I never have warm beer,” quips Adams.