Saturday, February 4, 2012

Pico PV: a real solution for rural electrification?

Pico PV has emerged as a new keyword in rural electrification. Also called Solar Pico Systems (SPS), Pico PV are the younger brothers of Solar Home Systems (SHS) and could enable people in non-electrified areas to get access to modern energy services in cases where the cost is not affordable or the energy demand is too low to be powered by SHS. In this regard, Pico PV can also help to replace current expensive and polluting kerosene lamps and dry cell batteries.
SPS are "Plug & Play" systems typically below 10 Wp and mostly with a voltage not above 12 V. The cost ranges from $2 to $ 200, being most of the times below $100 (check the graph below)

Several innovations over the last years have contributed to the development of Pico PV systems:
·         Fall in the price of PV modules
·         Advances in the development of LED technology.
·         Improvement of the life cycle of modern accumulators
LED technology:
Modern LEDs can provide bright electric light (up to 160 lm/W) with very little electrical power. In this regard, LEDs are up to 15 times more efficient than conventional incandescent lamps and about 3 times more efficient than good CFL lamps. Nonetheless, there are also SPS powering CFL lamps, but it is not very common.

Rechargeable batteries are the most expensive component when considering the cost over the SPS lifecycle. As shown in the picture below, there are a variety of technologies available with different efficiencies, demand in terms of charge controller, lifecycle, etc.

Distribution channels and After Sales Services are required to ensure the access to high quality and certified products, the protection of user rights (warranty claim) and the availability of spare parts and replacement of components (batteries mainly)
A few considerations:
Lead Acid batteries: are usually too heavy compared to the size of a typical SPS and tend to fail due to sulfation.
NiCd: should not be used as Cd is a poison and most of the target countries do not have a proper recycling program
Nickel Metal Hydrate (NiMh): show no sulfation and are also much lighter. Special types of NiMh batteries have a low self-discharge behavior and most of them do not need a charge controller or, if so, only a relatively simple one.
Li-Ion batteries: still remain relatively expensive but are high energy density, so allow more charge/discharge cycles (check LIFePo in the picture above) and also a smaller size. Most of them present an excellent efficiency.
Two different topologies of Pico PV systems are available:
Pico solar lanterns: besides providing light, some of them also provide energy to charge a cell phone or operate a radio.
Pico PV Home Systems: can provide energy for several lights, a radio and charging a mobile phone. Under this configuration, SPS are scalable and so can be extended in case the electricity demand grows over the years. Additionally, this scalability also provides a strategy for financing the system. Instead of paying connection fees and undertaking to pay a fee-for-service every month, users can upgrade their systems gradually when their economic circumstances allow it.
What are the current limitations of SPS in the rural electrification market?
Quality: gates are opening for bad quality products at very low-cost which often relates into higher cost compared to the existing solution (e.g. kerosene) This includes lab and field test according to international standards, product labels, instruction manuals. When talking about Led lamps, this becomes essential. The field tests have revealed that lab tests alone are not enough, since lamps which have been successful in the lab, usually show significant technical problems in the field (5)

That is, Trust Marks are needed.

Consumer education: some results from field surveys show that users often place their solar lamp on a table in their main room (as they did with former kerosene lamps) even if this inhibits an optimal light distribution.  Also it is often that users place the panels in inappropriate places for charging (5)

Recycling and Post Return: Only in Africa the potential market amounts to 300 Million people. The problematic of electrical waste and how to recycle the products have to be integrated into the product assessment yet.
Saturation effect: user willingness to pay is highest for the first kWhs and decreases with the amount of electricity consumed.
Solar lighting as merit good: improving studying conditions, improved air quality and reduced safety risks when replacing kerosene lighting…These social and psychological effects of the use of Pico PV systems that go beyond the easily measurable socio-economic benefits are usually in the mind of policy-makers but has to be “transferred” to the end users through suitable informative campaigns (4)
2012 is the International Year of Sustainable Energy for All, but no consensus exist to the date on how to define a minimum service level at which a household can be classified as “electrified”, that is, what is the Basic Electrification Threshold. And also in this regard, what is the difference between lighting and electrification?
Typical SHS and mini-grids based electrification programs provide electricity in the range of 150-200 Wh/day/home. If that is the reference, it seems clear that Pico PV systems are not the solution for the rural electrification challenge. Nevertheless, they can become a perfect complement of those in electrification programs to power the poorest people that cannot afford the cost of the connection fees or are out of the scope of the mini-grid. Also, SPS seems to be a good tool to raise interest among rural people in environmental-friendly and long-term cost effectiveness solutions to power their homes.
However, according to my experience, Solar solutions are often considered as low-cost and low-quality solutions among the rural people, mostly because of bad practices in some projects implemented (not always related to technical issues but to lack of long-term sustainability of the projects) In this context, current situation of  Pico PV market does not help at all to revert this situation and a great effort to define minimum international standards are needed.
Author’s observations
(1) Solar Pico Systems: Problems, opportunities and solutions. Andreas Paul (Phocos AG)
(2) Ways to protect consumers from low quality Pico PV products (GIZ)
(3) Pico PV: Policy implications of a new technology option (GIZ)
(4) Pico PV: An overwiew. Prof. Peter Adelmann (Univ. of Applied Science,Ulm)
(5) How are Pico PV lamps performing under real-life conditions in developing countries? Anna Brüderle (GIZ)
* All the above are papers presented during the 2nd Symposium on Small PV-applications (Ulm, June, 2012)


  1. May I introduce FRES from The Netherlands;
    Emilio visited us long time ago in Mbarara Uganda. We have started our operations in Mbarara end of last year after some 'traditional african delays'. FRES Uganda Ltd offers Solar Home Systems on a 'Fee for Service' model from Energy Stores close to the people into the rural areas.
    With this model FRES keeps ownership of the SHS and supplies the so much needed service on SHS systems close to the people in the rural areas. FRES is charging a fixed fee per month between (9 to 14 Euro)for the services and replacements of worn out parts. SHS-systems (55Wp, 110Wp and 165Wp) are affordable for the middle to higher income groups. So we are looking into offering PV-Pico systems next to SHS to allow poorer people access to lights too, replacing the kerosene lamps. Only with quality equipment, a service network close to the people and education on how to use PV solar systems rural electrification becomes sustainable.

    1. Yes, I think SHS + SPS are a good marriage. Also Pico PV is a good complement when implementing mini-grids since not only provides an alternative for the lower income segment but also to those who having capacity to pay, are out of the scope of the mini-grid. Obviously, SHS are also a valid option for these last case.

  2. Very good summary of the pico PV state of the art.Thanks to share this info with us

  3. Nice summary of the picoPV issues and some of the current thinking. I'm working in pico-PV at the moment, with Barefoot Power ( with current products being lanterns and pico-SHS from 1.5W to 15W. We have been addressing the issues of sustainability through moving to the LiPO4 batteries, providing 12 month warranties and implementing battery recycling channels and regional repair stations in the countries where we operate.

    Removing kerosene use with picoPV that can pay for itself in less than 6 months is the first step to sustainable energy for all. It saves money, allowing the user to move up the energy chain or spend on other priorities like food or education for their kids.

    The idea of a Basic Electrification Threshold has some merit, but I think it focuses too much on the energy provided rather than it's application. Is 150Wh through an incandescent bulb better than 15Wh through an LED? 5 hours of an efficient 12V LED TV should be equivalent to 5 hours of an old cathode ray tv independent of the Wh. And then there are the other energy sources such as biogas or water pumping windmills which provide an energy servie without the electrification.

    Maybe the BET could be changed to a Basic Energy Services Threshold (BEST), although this of course becomes much more difficult to consistently define.

    1. Yes, I totally agree. According to IEA definition of "electricity poverty", that means no access to at least 120 kWh of electricity per year for lighting and other basic households needs. But as you pointed out, it should be also standarized what mimimum energy services are expected to be included in such quantity.

      And when talking about thermal needs to be powered by biomass stoves, for example, an agreement about what means "energy poverty" would be also needed.

  4. Very informative post!
    Thank you, Emilio.

    Regarding standards,
    I am in touch with Sproxil (
    and a few other alternatives.

    What it does is that every quality product has a sticker with a code,
    and villagers can verify that with SMS.
    There is also a country hot-line for inquiries and after-sales.

    So a third party issues the stickers to quality producers,
    and can keep track of the users (villagers) in case there are installation problems or
    after sales needs.

    I can keep you updated,
    and also hope to learn your opinion.