Lamps and Electric Appliances
Overview
Lamps
For information on lighting technologies see the Technologies report prepared for HERA.
It contains information on:
Audio and Video Devices
Most appliances such as TVs, receivers or video recorders operate on alternating current (AC). There are a few exceptions including some DC TVs. Color TVs consume more than black & white ones. There are considerable differences between individual brands. TVs should not be operated on stand-by. Controllers and inverters may disturb operation of TVs and radios.
| Power demand of color TVs | |
| Size | Power |
| 17 cm | 20 W |
| 25 cm | 40 W |
| 37 cm | 60 W |
Transistor radios and cassette players are operated by batteries at a voltage below 12 V. Since batteries are expensive, such appliances should also be connected to the solar system through a voltage converter.
Water Pumps
Photovoltaic (PV) powered water pumps are increasingly attractive for off-grid solutions to water supply due to the abundance of solar radiation and a corresponding increase in demand to provide water for domestic and irrigation.
Solar pumping systems consist of four major components:
- PV array (up to 5 kWp), power conditioning units,
- a pump set,
- water storage and
- distribution system.
Battery storage is not essential as water can be stored.
Solar water pumps are appropriate for household and community water supply, livestock watering as well as small-scale low-head irrigation. They are best suited for applications where head is medium or low (few PV pumps are deeper than 100m) and where water demand is steady but low (< 200 m4/day). Proper sizing and installation of systems is critical for optimum utilization. PVP is preferable to diesel pumping when water requirements are low, sunshine abundant, and when supplies of fuel are far away. Several PV pumping initiatives have been undertaken in the region by donor agencies, relief agencies and missionaries for domestic water supplies, livestock and irrigation.
Cost is dependent upon system size. Hardware costs range from $3,500 for a 0.18 kWp system (head 5 –15 m, output 3-12 m3 /day) to $15,000 for a 2kWp system (up to 200m head, out put 10 m3). Smaller DC powered, low head (0.5- 5m) low yield (3- 5 m3/day) PV pumps are also available approximately $ 800[1].
Some tens of thousands of pumps powered by solar generators are currently in use worldwide. A variety of pumps for low water demand are available on the market. These include single-stage centrifugal pumps for lifting heads < 10m and diaphragm pumps for larger heads, both DC- and AC-operated. They are surfacemounted, floating or submerged pumps. DC pumps with brushes need regular replacements.
The energy requirement (E) for a daily water demand (Q), a pumping head (h, water level to tank inlet or pipe outlet) and a pump efficiency (η = 0.2-0.4, depending on type and pumping head) is
E [kWh] = h [m] x Q [m³/d] / 367 / η
Refrigerators
Photovoltaic (PV) vaccine refrigerators, an early application of solar electricity, are used to maintain the cold chain required by vaccines in especially rural off grid health facilities. Under the World Health organisation (WHO) –EPI program, numerous health facilities across Africa have benefited from PV and LPG powered vaccine refrigerators. This created a constant demand that was a driving force for PV industry in the region.
Typical PV refrigeration systems consist of a PV array, system controller, battery bank and specially built vaccine refrigerator. Because of the strict WHO standards on manufacture and installation, and high attention to maintenance, a very large proportion of vaccine refrigerators remain operational even under the adverse conditions of remote sites. Technical specifications for medical refrigeration are set and approved by WHO - standards PIS E3/ 39[1].
Refrigerators are available for AC and DC. DC refrigerators are more expensive. They cost more than 600 €. The size has only a small effect on the price. Only low-consumption refrigerators of the compressor type are suitable for solar systems. A 100 l high-quality refrigerator without an icebox may consume approximately 300 Wh at 24°C and 450 Wh at 32°C. Ice production, a high demand for cold drinks and a low-efficiency type can easily double or triple this figure. Box types are more efficient. Special types are available for vaccine storage. Starting at low voltage levels (<11.5 V) is a problem for many refrigerators.
Further Information
- For information on lighting technologies see the Technologies report prepared for HERA.
- For case study on Uganda, see Solar Lamps in Uganda, GIZ field Report
- For information about PicoPV distribution models, see Lamp Distribution Models
