Frequently asked questions

 

How do temperature and weather conditions influence the performance?

  • Sunshine: 100% recharge performance
  • Slightly overcast : 85% recharge performance
  • Overcast: 50% recharge performance
  • Slightly overcast winter day, partially sunny (1 – 2h): 25% recharge performance
  • Longer overcast period: 5% recharge performance
  • At -20°C (-4°F) the capacity of the battery is lowered by 30 % and the lighting performance of the LEDs is also decreased by 20 %.
  • Due to the fact that the sulfuric acid in the battery changes to water (among other things) in the process of emptying, the contents of the battery can freeze at very low temperatures if it is not being recharged (due to a defect solar panel or some other reason). To guarantee a long battery life, the controller has an integrated low voltage battery saver.

How high must the lighting performance be in W/m² (W/feet²) or Lux and for how long must it be so high to fully charge the battery?

  • First, we have to take the geographical and meteorological properties of the place of usage into account. 
  • Important notice: The sun's lighting performance in Austria is approximately 1000 W/m² (93W/feet²).
  • Summer: 2-3 days are necessary to fully recharge the battery. Due to the panel pitch, the efficiency is around 12% (the battery is emptying during the night, as the lamp is in operation).
  • Winter: 3-5 days are necessary to fully recharge the battery. Due to the panel pitch, the efficiency is around 16% (the battery is emptying during the night, as the lamp is in operation).

 

Light used to generate electricity

  • For the production of electrical energy, only UV rays and the rays of visible light are used, therefore the solar panel should face south. The overall efficiency is about 18 – 20%. If the panel pitch is not correctly set, the efficiency drops down to 14%.

Should the panel position be adjusted for summer and winter operation?

  • No, the panel should be adjusted for winter operation.
  • During the summer the efficiency is lower, but that makes no difference, as the prolonged hours of sunshine ensure the same performance.

Battery and solar panel life expectancy

  • The life expectancy of the battery is around 5-6 years.
  • The life expectancy of the solar panel is around 25 years. 
  • The performance drops after 20 years in operation about 2-3% every year. It's not noticeable before that. 

Measurement: Apollo (PL-176c)

  • Height of the light source: 3,5m (11,5 feet)
  • Performance: 16W LED (4W in each direction).
  • The measurement of the light intensity has taken place 20 (8 inches) above ground.
  • How high is the light intensity under the lamp and in a radius of 2/5/10m (6.5/16/33 feet) 
  • Under the lamp: 3,6 Lux | 2m (6,5 feet): 4 Lux | 5m (16 feet): 3 Lux | 10m (33 feet): 1,5 Lux

The following measurement was taken to compare our lights to conventional street lights.

Measurement: 125W high pressure mercury lamp

  • Our test lamp had no milky glass in the fixture (it can affect the results)
  • Height of the light source: 3,5m (11,5 feet)
  • Performance: 125 W
  • How high is the light intensity under the lamp and in a radius of 2/5/10m (6.5/16/32 feet) 
  • Under the lamp: 35 Lux | 2m (6,5 feet): 19 Lux | 5m (16 feet): 7,5 Lux | 10m (33 feet): 1,5 Lux

Result

  • The power consumption of the high pressure mercury lamp is 8 times higher than the power consumption of the solar light.
  • The lighting performance, however, is not 8 times, but only 2.7 times higher compared to the solar light.
  • That means that the solar light is much more efficient.
  • LEDs have a higher life expectancy than high pressure mercury lamps.
  • Solar lamps also do not emit some part of the light spectrum, so that insects feel less or not attracted to them.

 Properties of the controller unit

  • Changes that happen throughout the year (sunrise, duration of the day/night, sunset) are tracked by the controller unit. The time of the sunrise/sunset is saved so that the lighting duration can be adjusted automatically.