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Solar + battery energy storage VS diesel in East Africa

Solar Battery

Solar PV + BESS plants are an economically more competitive solution to providing power for customers that do not have access to the electricity grid or for those who have unreliable grid connections.

Diesel generators are deployed extensively in East Africa to compensate for no grid to frequent outage scenarios:

Diesel generator power in East African countries
Fuel Cost
Diesel LCOE: USD/kWh
Adjusted for
non Fuel Costs
Kenya 0.99 0.3 0.36
Uganda 0.97 0.29 0.35
Tanzania 0.91 0.28 0.34
Rwanda 1.12 0.34 0.41
Burundi 1.27 0.38 0.46

(source: Energy Regulators websites, Authors models)

Levelized cost (LCOE) of diesel

The total costs of energy from a diesel generator can be broadly summarized as:

  • Capital cost of acquisition
  • Generator maintenance costs
  • Diesel costs: purchase price, transportation & storage costs, working capital costs, pilferage & fuel shrinkage

To simplify the analysis, several technical and economic assumptions are made in this LCOE calculation including optimal generator efficiency, maximum lifetime run hours and generator usage.

Solar + BESS power (LCOE)

The illustration below demonstrates observed costs from a 650kVA / 2320kWh BESS plant coupled to a 900KWp Solar PV plant, which was able to achieve a LCOE of US$ 0.14.

SOLAR PV PLANT Installed Cost USD 1,200/KWp 25yr Lifetime
SOLAR PV Plant Maintenance  USD 20/KWp per annum
PV Plant Replacements / Upgrades 15% of plant cost in YR 11 PV Inverter Replacement
Solar PV Annual Yield 1450KWH/KWp 2% Degradation
BESS Installed cost: USD 415/KWh
BESS Warranted Lifetime 15Yrs
BESS Round Trip Efficiency  90%
BESS Depth of Discharge 100%
Discount Rate 8%
10.BESS Replacement YEAR 16 40% of today’s BESS Costs
11. Curtailment 10% of Solar PV Yield
12. Level of Diesel Replacement 100%

Solar PV energy prices have declined sharply over the last few years and the LCOE is now between USD 0.05/kWh and USD 0.08 /kWh for commercial scale systems in East Africa, making it competitive with several conventional sources.

However, mass adoption of Solar PV has been hindered due to its intermittent downfalls – both from a real time perspective (sudden cloud cover) and a long-term perspective (available only during the day).

The addition of energy storage solves this problem, but increases the overall cost of the solution. Therefore, optimal sizing of the energy storage system is a crucial step in increasing solar PV capacity to effectively and reliably meet electrical loads while delivering an economically competitive LCOE.

An Energy Storage Consultant will help determine the optimal solar PV and battery energy storage sizes required to yield a lower blended LCOE to the customer while also providing reliable power.

Examples of common sizing strategies include:

  1. No energy storage: In an off-grid microgrid with only diesel generators and solar PV. Real-time PV is intermittently mitigated by using generators as spinning reserves. Nevertheless, due to minimum loading requirements of the gensets, PV capacity is typically limited to 60% of day-time load.
  2. PV + storage sized for day-time load: With this strategy, battery energy storage provides real time firming of PV power and creates a base-load generator, thereby enabling the turning-off of gensets from a few hours a day.
  3. PV+ storage sized for 24 hr energy: To power the load entirely with renewables, Solar PV is sized to provide the load’s energy needs and the round trip efficiency of Battery Energy Storage System (BESS). The site controller intelligently charges/ discharges during the day (mitigating real time intermittency) and discharges when the sun goes down (mitigating long-term intermittency).

In summary, several selling points make solar PV with BESS an attractive alternative to using diesel generators to produce power:

  • Falling solar prices,
  • Falling storage prices,
  • Expectations that  diesel prices will increase,
  • Reduction of greenhouse gas emissions, and
  • Reduction in noise during operation.

Current prices of solar and storage make it feasible to turn off diesel gensets and provide firm power for several hours. Falling prices will expand the window of hours that diesel generators can be turned off completely.