The increasing global demand for renewable energy necessitates a comprehensive understanding of solar photovoltaic (PV) system performance and reliability, particularly in harsh climates such as Iraq. Despite ambitious targets to diversify its energy sector, Iraq faces challenges in the deployment of PV projects due to limited field experience. In this study, we assess the reliability and performance of two different PV systems installed in Basrah and Baghdad, aged 3.5 and 8 years, respectively. Field analysis reveals prevalent issues including glass and cell breakage, delamination, solder bond fatigue, and encapsulant discoloration, contributing to medium degradation rates of 0.91 %/year and 2.6 %/year in Basrah and Baghdad, respectively. Our investigation attributes higher degradation rates not only to ageing but also to suboptimal operation and maintenance (O&M) practices. Additionally, since the two systems are from different manufacturers, we verify that the measured higher degradation rates are mainly attributed to harsh operating conditions rather than differences in manufacturing processes. To extrapolate our findings countrywide, we employ a physics-based model to simulate the degradation rates. Based on the simulated degradation, we proposed four degradation rate zones across the country with degradation rates ranging from 0.62 %/year to 0.96 %/year. By applying these rates to estimate lifetime energy yield across different zones, we demonstrate the trade-offs between higher irradiance zones with reduced PV lifetime and low irradiance zones with longer PV lifetimes. In the study, we compared energy yield simulations using fixed degradation rates with those employing climate-dependent degradation rates. Our analysis revealed that in certain locations in Iraq, employing a fixed degradation rate underestimates the yield by approximately 9.7 %. Conversely, in other locations, it results in overestimations ranging from approximately 10.5 %-31.1 %, highlighting the importance of accurate degradation rate modelling for PV system assessment. Furthermore, we simulate the impact of soiling losses on energy yield, revealing potential losses of up to 70 % depending on location and cleaning schedules. Our findings contribute valuable insights into PV system degradation across harsh climates, addressing critical gaps in global degradation rate data and facilitating more accurate climate-dependent assessments of PV performance and reliability.

Bioenergy cropping, like all agricultural practices, may lead to the release of greenhouse gases. This study was aimed at determining biomass and energy yields of reed canary grass (RCG) (Phalaris arundinacea), galega (Galega orientalis) and a mixture of these, and to relate these to fluxes of nitrous oxide (N2O), a potent greenhouse gas, emitted from the soils. Plots including a bare fallow as control were established in 2008. Gases emitted from the soil surface were collected in closed chambers from May 2011 to May 2013, except during periods of snow cover, and analysed by gas chromatography. Seasonal and annual cumulative emissions of N2O and CO2 equivalents per unit energy yield were calculated. Soil moisture content, nitrate (NO3 (-))-N and ammonium (NH4 (+))-N were also determined. Both species composition and crop yields affected energy yields and N2O emission from the soil. The annual cumulative emissions from mixture were marginally lower than those from fertilized RCG soils. Fertilized RCG produced twice as much biomass and correspondingly higher nitrogen and energy yields, so its low emission of N2O per Mg of dry matter was not significantly different from that of the mixtures. Cropping an RCG-galega mixture for biofuel may replace N fertilizer input since it resulted in lowering N2O fluxes, but requires management to maintain grass as the major component in order to minimize N2O emissions. In a time of climate change, low-input bioenergy crops may be a suitable strategy for land left uncropped after ploughing for one season or longer.