30 May - 5 June 2014 #709

A sunnier future

Net metering could turn every household into a power generator and reduce load-shedding hours
Maneeshika Madduri

EXPERIMENTAL:The Nepal Electricity Authority is testing reverse-metring with its own grid-connected 3 x 1.11 kW roof system in Min Bhawan which can reduce daytime load-shedding (graph, below).
This month power cuts were only reduced from 84 hours per week to 70, still keeping one of the world’s most water resource rich countries in darkness.

Hydropower makes up most of the energy dispensed to the grid, but the Nepal Electricity Authority (NEA) can meet only 77.5 per cent of energy demand. More hydropower plants are under construction, most of them run-of-the-river systems, but these take time and money.

Nepal's natural resources extend beyond rivers, and its solar potential is nearly ideal, with an average of ten hours of sunlight per day all year round. Solar radiation peaks during the clear, sunny days of winter months, complementing hydro seasonality lows.

Solar photovoltaic (PV) panels have become a familiar sight in Nepal, as the electricity shortage pushes people to opt for solar power in both grid-connected and off-grid areas. Solar home systems consist of batteries, a charge controller to monitor battery charging, and PV panels.

Energy generated by the PV panels can be stored in batteries for use later. But batteries are expensive, and solar home systems aim to minimise the necessity of batteries.

It is not uncommon to have full batteries and unused energy: an office on the weekend or a house on a sunny day. Injecting this excess electricity back into the grid is possible through grid-connected systems that allow electricity to flow in two directions, from the grid to the loads or battery and from the solar panel to the grid.

This requires a grid-tied inverter, which monitors these connections, and a meter that indicates the net energy consumed. To determine the feasibility of grid-connected rooftop PV systems in Nepal, a pilot research project was spearheaded by Center for Energy Studies at IOE-Pulchowk, SUPSI (University of Applied Sciences and Arts of Italian Switzerland) and RIDS-Nepal (Rural Integrated Development Services). By January 2014, a year of data had been collected from the five 1.11 kW solar PV rooftop system.

Currently, tying a private solar system to the grid is not permitted in Nepal and requires case-by-case approval. Net metering, which enables consumers to be charged by the utility for energy consumed minus energy injected to the grid, is not allowed. The objection to grid-connectivity and net metering is primarily financial: solar is seen as too expensive to supplement the electric grid. However, this argument has some weaknesses.

The per unit price of solar is traditionally determined by the initial investment and operational costs over the lifetime of the panels (typically 25 years) and the energy generation potential. From recent data, the annual energy expectancy for a 1 kW system is approximately 1500 kWh. Given this potential, the break-even price point for grid-connected solar could be as low as Rs12/kWh. This is not yet on par with the current selling price of electricity, which is the argument cited against net metering, but that may not matter.

This rooftop photo-voltaic solar home system at a research station in Imadol has collected one year of data on how household power fed into the grid can reduce load-shedding.
Any financial recompense would be seen as preferable to the present one, and would encourage more solar installations. On a more pressing level, grid-connectivity of solar installations would directly inject much needed energy into the grid, locally lessening load-shedding.

Rooftop solar systems are not the only option. Large-scale solar installations are viable in Nepal, and have the potential to impact energy generation significantly. The graph shows the power profile for a day in January with a projected 100 MWp (megawatt-peak) solar energy contribution, supplied either through small-scale, roof-top systems (1–5 kW) or several larger constructions (1-10 MW). These types of installations can reduce daytime load-shedding nationwide by approximately 9-10 hours per week and, in conjunction with some hydropower storage capability, possibly also during peak evening hours.

With an ever-increasing electricity demand, solar PV systems act as a timely and effective means to deal with Nepal’s power crisis. Allowing grid-connectivity and net metering is a crucial step towards reaching key energy diversification and reducing load-shedding.

Read also:

Greening of Annapurna, Basil Edward Teo

No alternative to alternative energy, Bhrikuti Rai

Bring home the sunshine, Paavan Mathema

The sun is free for everyone but not for Nepalis, it seems, ADAM FRIEDSOHN

Maneeshika Madduri is a recent graduate of Stanford University and is currently a Fulbright Student Scholar in Nepal. Contact her at mmadduri@alumni.stanford.edu