In 1988, 86 solar home systems, SHS, and 15 street lighting systems, SLS, were installed
in the village of Sukatani in the province of West Java of Indonesia. The systems have a
PV array of 80 Wp.
In this paper we analyse the performance of these systems. For this purpose we use
monitoring data and data from ®eld surveys recorded in the period 1988±1993 and data
collected in a ®eld survey in 1997. This survey comprised both technical measurements on
62 solar home systems and interviews with 22 users of these systems.
We found that, although the failure rate of street lighting systems is high, the villagers
have a positive opinion about these systems.
Further, we found that technically the solar home systems performed well. The users are
satis®ed about the performance. However, in the course of time the con®guration of the
SHS has changed: villagers have replaced most of the strip lights with cheap home-made
candescent lamps and have replaced the initially-installed 100 Ah capacity solar batteries
with cheaper locally produced 70 Ah capacity car batteries.
From an analysis of monitoring data we found that the average irradiation in Sukatani is
/day, which is a common value for Indonesia, but more than expected in 1988
when the systems were installed (3.5 kWh/m2
/day). Furthermore, we found that daily the low demand of electricity the average performance ratio is 49%. By means of an energy
loss analysis of the PV systems we found that 15% of the theoretically available energy
from the array cannot be fed in the battery because it is fully charged.
The replacement of 100 Ah batteries by 70 Ah batteries was justi®ed on the grounds of
the low electricity consumption of the SHS users in the period 1988±1993. On the basis of
®eld surveys we found that the average lifetime of the 100 Ah and 70 Ah batteries is 4 and
3.5 years, respectively. The realized battery lifetime is rather long compared with other SHS
projects in the world.
While the average battery size in Sukatani decreased in course of time, we found on the
basis of interviews with users of SHS that the average daily electricity consumption
increased. We found a value of 18 Ah/day in 1997.
Furthermore, the spread in the demand of electricity in 1997 and the use of other than
initially-installed appliances, such as small incandesent bulbs and intercoms, indicates the
need for a broad o€er of system sizes and low power appliances. By means of design
calculations we found that PV arrays in the range of 35±130 Wp are needed to satisfy
di€erent demand patterns.
We conclude that monitoring by means of data loggers is a useful approach to allow the
analysis of the long-term system performance. To increase the statistical reliability of
results, monitoring should be supplemented by ®eld measurements and interviews with
users. However, due to the deviation between real and narrated experiences, interviews
alone may not be su�cient to assess an SHS project. # 1999 Elsevier Science Ltd. All