Exploring future energy solutions in Ghana with FPV/PHS hybrid system through techno-economic analysis

Abstract

Ghana accommodates abundant solar resources and has a goal of installing 425 MW of new utility scaled photovoltaics by 2030. Would conventional ground-based photovoltaics (PV) or the growing floating PV (FPV) technology provide a better solution for the solar installation? What about combining the FPV with a hybrid system including pumped hydro storage (PHS) to improve flexibility and stabilise reservoir levels?

These questions created the framework of what this thesis has examined through a techno-economic analysis with the use of hybrid energy optimization software and a newly developed site evaluator engine for FPV. To establish a comparison between ground-based PV, FPV and the hybrid option with FPV and PHS, two locations with existing hydropower plants in Ghana were selected. The Akosombo and Bui hydropower plants have a current installed capacity of 1,020 MW and 400 MW, respectively. To compare the solar PV potential of two locations, the planned installed effect of 425 MW was evenly split between the two hydropower plants.

The results showed that ground-based PV yielded around 275 GWh annually for each of the two locations with a levelized cost of energy (LCOE) of $0.098/kWh. This is slightly higher than average industry values ranging from $0.047-0.053/kWh, but well below the currently largest PV site in Ghana; Navrongo ($0.2411/kWh). Choosing FPV over ground-based PV increased the yield by 18% and 16% for Bui and Akosombo, respectively, at a marginally higher LCOE ($0.104/kWh and $0.106/kWh).

Coupling FPV with PHS yielded annual output of 262.43 GWh to the grid where the FPV efficiently charged the reservoirs in the dry months. LCOE came to $0.234/kWh, which is lower than most thermal plants in Ghana. Further comparison between the FPV/PHS hybrid solution and thermal plant showed a simple payback period of under 13 years before the cost of the hybrid system was lower than diesel-fuelled thermal system. Changes in both FPV capital cost and fuel prices had a strong correlation with preferred system solution. With fuel prices above $0.5/L, PV were part of any suggested solutions with PHS. The analysis discovered certain software limitations where further development in optimization software for hybrid PHS and possible site feasibility studies in Ghana could strengthen the theoretical foundation.

Ghana har gode solressurser og ønsker å installere 425 MW med ny solcellekapasitet innen 2030. Hvilke alternativer kan gi de beste løsningene? Er landbaserte solceller (PV) bedre eller kan flytende solceller (FPV) gi et bedre resultat? Og kan et hybridsystem som inkluderer lagring med pumpekraft, forbedre fleksibiliteten og stabilisere vannstanden i dammene? Dette skapte rammeverket for hva denne masteroppgaven har undersøkt i et tekno-økonomisk perspektiv med bruk av optimaliseringsprogramvare for hybride energisystemer og en ny evalueringsprogramvare for FPV. For å få en sammenligning mellom landbasert PV, FPV og hybridalternativet med FPV og pumpekraft (PHS), ble to steder med eksisterende vannkraftverk valgt. Vannkraftverkene Akosombo og Bui har henholdsvis 1.020 MW og 400 MW installert kapasitet. For å sammenlikne potensialet på det to lokasjonene ble den planlagte installerte effekten på 425 MW fordelt likt mellom de to vannkraftverkene.