Global Progress Toward Renewable Electricity: Tracking the Role of Solar (Version 3)

2022 was a milestone year for photovoltaics (PV), with cumulative installed global capacity exceeding 1 TW. PV represented 56% of newly installed global electricity generating capacity for 2022, the second year in a row that this metric exceeded 50%. The combined contributions of nonhydro renewable electricity generation (solar, wind, tidal, geothermal, and biomass) was comparable to that of hydropower for the first time in history. However, the total combination of carbon-free generation sources (hydro, nuclear, and renewables) stayed constant at ∼38% of total electricity, with the annual growth in overall generation (∼2%) balancing the large fractional growth in solar (25%) and wind (14%). Following its initial publication in 2021 with 1990–2020 data, this annual article will continue to collect information from multiple sources and present it systematically as a convenient reference for IEEE JPV readers. This year, for the first time, we present data on the growth of storage capacity. We find that growth of stationary battery storage now exceeds growth of pumped hydropower storage. That same annual investment in new stationary batteries, however, is small compared to the growth of battery storage in electric vehicles.

Global Progress Toward Renewable Electricity: Tracking the Role of Solar (Version 3) Nancy M. Haegel , Member, IEEE, and Sarah R. Kurtz , Fellow, IEEE Abstract-2022 was a milestone year for photovoltaics (PV), with cumulative installed global capacity exceeding 1 TW.PV represented 56% of newly installed global electricity generating capacity for 2022, the second year in a row that this metric exceeded 50%.The combined contributions of nonhydro renewable electricity generation (solar, wind, tidal, geothermal, and biomass) was comparable to that of hydropower for the first time in history.However, the total combination of carbon-free generation sources (hydro, nuclear, and renewables) stayed constant at ∼38% of total electricity, with the annual growth in overall generation (∼2%) balancing the large fractional growth in solar (25%) and wind (14%).Following its initial publication in 2021 with 1990-2020 data, this annual article will continue to collect information from multiple sources and present it systematically as a convenient reference for IEEE JPV readers.This year, for the first time, we present data on the growth of storage capacity.We find that growth of stationary battery storage now exceeds growth of pumped hydropower storage.That same annual investment in new stationary batteries, however, is small compared to the growth of battery storage in electric vehicles.
Index Terms-Net expansions, renewable energy sources, solar energy, solar power generation.

I. INTRODUCTION
E LECTRICITY generation from renewable energy sources continued to grow in magnitude in 2022, and photovoltaics (PV) continued its growth both in magnitude and fractional contribution.Total electricity from all sources consumed globally in 2022 was ∼29 170 TWh, representing ∼17.2% of total energy consumption similar to 2020-2021 [1].The share of renewable power generation (hydro and non-hydro renewables, mainly wind and PV) remained at ∼30%.Newly installed generating capacity in 2022 for hydro, PV, and wind, was 82% of the global total, as shown in Fig. 2(c), with PV at more than 50% of new installed generating capacity for the second year in a row.The 2022 BP Statistical Review of World Energy [1] reported that "wind and solar reached a record high of 12% share of power generation."Nancy M. Haegel is with the National Renewable Energy Laboratory, Golden, CO 80401 USA (e-mail: nancy.haegel@nrel.gov).
Color versions of one or more figures in this article are available at https://doi.org/10.1109/JPHOTOV.2023.3309922.
Digital Object Identifier 10.1109/JPHOTOV.2023.3309922PV is now the most rapidly growing generation technology in the energy transition.Reports based on estimated deployment rates suggesting that the TW DC installed global capacity milestone had been achieved first appeared in March 2022 [2], and the 1 TW AC milestone was also reached by the year's end.The percentage of global electricity generated by PV, which we reported as 3.6% for 2021, was 4.5% for 2022, based on the ratio of gross electricity generation from solar to gross electricity generation from all sources reported in [1], a remarkable 25% fractional growth.Global 2022 electricity generation from wind and solar combined (∼3430 TWh) was greater than electricity generation from nuclear power plants (∼2670 TWh), up a significant 18% from the previous year (∼2910 TWh).Non-CO 2 emitting generation sources (nuclear, hydro, and combined renewables) contributed 38% of the world's electricity in 2022, similar to 2021.
The goal of this annual article is to present data, in consistent graphical and tabular form, on the global progress toward renewable energy.As discussed in the initial 2021 publication [3], multiple institutions provide global energy data on a yearly basis.These organizations have varying missions and varying reporting times for annual updates.Different institutions also vary in their use of original sources and methodologies.Some may change methodologies over time, while others share reporting data.Assembling this collection of frequently cited sources in one place illustrates both major trends and the nature and degree of variations within the source group.
Here, we update the following three sets of graphs: annual generation by broad fuel source for global electricity (see Section II); yearly generation and newly installed capacity for specific fuel sources with a focus on renewables (see Section III); and generation and capacity over time with a more detailed breakout of fuel sources including PV (see Section IV).This year we also begin to track energy storage (see Section V).Data are included from six primary sources: the Energy Institute Statistical Review of World Energy, published in 2023 for the first time by the Energy Institute [1], taking over this respected resource after 71 years of publication by BP; the international data presented by the U.S. Energy Information Administration (EIA) [4]; the World Nuclear Association [5]; the International Energy Agency (IEA) [6]; the International Renewable Energy Agency (IRENA) [7]; and REN21 [8].Short summaries of the mission and history for the six original organizations were provided in Appendix of the 2021 publication [3].The Energy Institute is a professional membership organization, founded in 2003 (with precursor organizations dating back over 100 years), and home to a range of energy initiatives.II, with open circles used to mark the other data sources.Data source variations, of interest for detailed understanding and analysis, are seen in the tabulated data, but are not significant when plotted on the logarithmic scale over time.

II. TRACKING PROGRESS TOWARD RENEWABLE ELECTRICITY
Electricity generation [see Fig. 1(a)], a measure of energy provided, is presented in TWh, where 1 TWh = 3.6 x 10 15 J. Installed nameplate capacity [see Fig. 1(b)] is the rated output of a generator or other electric power production equipment under specific conditions designated by the manufacturer.The "capacity factor" is the ratio of the actual output of a system or collection of systems under true operating conditions (reflecting, e.g., variable resource, facility downtime, performance variations, large scale climate effects, etc.) and the output of that electricity source operating continuously at its commercial product or plant rating.Capacity factors for electricity generating technologies vary significantly, both within a technology depending on the performance, and between technologies as determined by the physics of the particular energy conversion process and the variability of the electricity demand.Actual electricity generation [see Fig. 1(a)] is the most relevant information for understanding and tracking the evolution of the energy system in terms of contributing fuel sources.Installed capacity [see Fig. 1(b)] allows one to track the status of global installations and new technology investment.
Different organizations report source data using different fuel sub-categories.In Fig. 1, the Statistical Review values for fossil generation and capacity are determined by summing component data for oil, gas, coal and "other" (where "other" is pumped hydro, non-renewable waste and statistical discrepancies) to obtain a total fossil value.Nonhydro renewable totals are calculated by subtracting the sum of total fossil, nuclear, and hydro from the total electricity value.This addresses the fact that individual values for certain non-hydro renewable components (PV, wind, concentrating solar power, geothermal, etc.) were not uniformly reported in earlier years, though that situation has evolved rapidly.The EIA values are taken directly from the website [4] by selecting the desired categories.
Several trends are clearly illustrated in Fig. 1.As noted, electricity generation from combined non-hydro renewables in 2022 was almost the same as electricity generated from hydropower worldwide.Combined generation from nuclear power plants decreased slightly.Finally, as previously discussed [3], continued projected growth in non-hydro renewables, specifically PV and wind, compared to the growth rate in total electricity, suggests major potential for future electrification of other energy sectors, with corresponding benefits to overall efficiency and decarbonization.

III. TRACKING THE RATE OF CHANGE
In Fig. 2 The pie charts illustrate a major ongoing theme: the global electricity system continues to be dominated by fossil energy [see Fig. 2(a), but is undergoing an increasingly rapid rate of change [see Fig. 2(c)].We plot electricity generation, generating  capacity and net capacity expansions (new installation minus any decommissioning) to highlight both where we stand and the new installations that will drive the future electricity generating mix.Nonfossil generation sources (solar, wind, hydro, geothermal, and nuclear) constitute more than 80% of capacity expansions for the past three years.PV and wind combined are more than 75% of capacity expansion each year over the same period.
One interesting thing to note in Fig. 2(c) is that, based on the updates in the international installed capacity numbers from EIA for 2020 and 2021, the "new installations" fraction of fossilbased generation sources for 2021 is very small-an increase of only 3 GW (from 4433 GW to 4436 GW), though other sources suggest this will rebound for 2022.It will be interesting to monitor if the EIA 2021 value for fossil generation capacity increases as the data mature.This is a common pattern and would increase fossil fractional growth for that year.However, it may also be the case that new construction, for both coal and natural gas facilities, was delayed in 2021, due to the pandemic and supply chain issues.This would suggest that the reported all-time high in demand for coal-fired electricity (10 440 TWh, 36% of total electricity) in 2022 as reported by IEA [9] was accomplished via increasing utilization of existing assets.Finally, although we are not tracking these categories separately, it is interesting to note that five tidal stream devices (2.7 MW) and six wave power devices (165 kW) were deployed in 2022 [8].While these numbers are negligible on the overall scale, they do illustrate the growing diversity of renewable energy sources.
IV. TRACKING THE ROLE OF PV Fig. 3 shows yearly global electricity generation and generating capacity, from 1990 to 2022, but now breaking out the contributing technologies to the "nonhydro renewables" from Fig. 1.Source data are presented in Table VIII and IX, respectively.In Fig. 3(a), the solid lines again represent data from [1], with open circles used to mark other data sources.For Fig. 3(b), solid lines represent the data in bold in Table IX, with open circles used to mark the other data sources.We note again that source variations, although of interest for detailed understanding and analysis, are relatively minor when assessing major trends over the time frames of interest for the global energy transformation.
According to [1], electricity generated globally from PV in 2022 was 1322.6 TWh, continuing its rapid growth trajectory.

TABLE IX GLOBAL ELECTRICITY-GENERATING CAPACITY BY TECHNOLOGY (GW). TOTAL, NUCLEAR, AND HYDRO ARE TABULATED IN TABLE I(B)
PV-generated electricity exceeded 1000 TWh in 2021 for the first time in history, after decades of development, but could reach 2000 TWh within just a couple years.It is also interesting to note from Fig. 3(b) that PV and wind are now at very comparable global installed capacities, with wind reaching the 1 TW milestone in June 2023 [10].Wind produced 2015 TWh of electricity, reflecting its higher average capacity factor.Over 200 GW of PV was added globally in 2022.
Five different sources for solar (Statistical Review of World Energy, EIA, IEA, IRENA and REN21) are given in Table IX.Variations here can arise for multiple reasons.Among these are: variations in reporting PV capacity as W DC or W AC : differences that arise in reports of PV shipments versus installations, variations in cross-border electricity accounting, or handling of the balance between new and retired resources; and changing methodologies in source reporting.Those with interests in pursuing these variations can find further details in the primary sources.
Reporting of solar electricity and capacity has been composed in the past of contributions from both PV and solar thermal power, depending on the source.As discussed last year, the rapid growth in PV since 2005 has made PV the increasingly dominant contributor to this broader solar category, a trend that accelerated in 2022.Tables VIII and IX indicate whether solar data is a combination of these technologies or PV only.These tables also indicate our assessment of which data are W DC or W AC .However, we note that there may be inconsistencies in the documentation of dc and ac PV ratings and that some sources may include a mixture of ac and dc data.

V. TRACKING ENERGY STORAGE
Pumped hydropower is the dominant energy storage technology supporting the electricity grid.However, Fig. 4 shows how its dominance is beginning to change.While pumped hydropower is and will continue to be the largest storage asset in the near future, with ∼ 175 GW of global storage capacity in 2021, batteries (e.g., lithium batteries) are now being installed at a rate that exceeds the typical expansion of pumped hydropower.Fig. 4 plots EIA data for the cumulative global pumped hydropower   in the values for Fig. 4, suggesting that the total installation rate of batteries is actually higher than shown.
While Fig. 4 tracks the installed power capacity for storage, a better metric may be the amount of electricity that is delivered by these assets.We were unable to find a public data set estimating the electricity from batteries globally, but, noting that the United States hosts a substantial fraction of the grid-scale batteries, Fig. 5 shows the electricity delivered from three storage technologies from 2017 to 2022 as reported by the EIA [12].The electricity from flywheels and batteries is partially used for ancillary services, but this capacity is being increasingly used to shift solar electricity for use after the sun sets.This new use may explain the doubling of electricity from batteries seen for both 2021 and 2022.
While the growth of batteries for stationary storage has been spectacular, the global fleet of electric vehicles (EV) already represents a larger energy storage capacity than the stationary storage.The IEA estimates that EVs sold in 2022 had batteries with a total of 550 GWh of capacity [13].While it is challenging to compare vehicle and stationary storage, the total power rating of 11 GW of stationary batteries presented earlier represents ∼ 22 to 33 GWh of energy capacity based on commonly cited lithium battery power-to-energy ratios (∼2-3) [14].One sees that energy storage capacity is substantially larger today in the EV fleet than in grid-scale stationary applications.We will begin to present the storage data in table form as more of the primary data sources begin tracking that information.At the same time, PV provided just ∼ 5% of 2022 global electricity generation.However, new levels of penetration of PV were achieved on electricity grids around the world, reaching or exceeding 20% in leading markets such as California, South Australia and Hawaii [15].At the end of 2022, nine countries had PV penetration levels on their national grids in excess of 10% [16].PV is at the cusp of the energy transformation, with the next 5-10 years playing a critical role in determining our ability to reach 2035 and 2050 decarbonization goals.
Batteries are increasingly being used to shift the time when the solar electricity is delivered, especially in those locations where solar exceeds 20% of the generated electricity.Worldwide, batteries are now being added for grid storage faster than pumped hydropower storage is added.The rapid growth of batteries for grid storage parallels the even larger growth in using batteries to power EVs.
The global PV R&D community continues to play a significant role.PV device innovation continues [17], and commercial products continue to advance in both performance and reliability.Reliability and module lifetime play a major role in reducing projections for the amount of both virgin materials required and end-of-life waste anticipated.A growing body of work is addressing the need for a circular economy for PV, identifying key levers for sustainability and anticipating raw materials and supply chain needs for multi TW scale.R&D needs are being identified to develop new approaches to recycling and materials recovery.
In addition to the growth documented here for utility, commercial and residential PV, opportunities for "PV Everywhere" (e.g., integrated with agriculture, broadly integrated into buildings, on reservoirs, etc.) are also growing, as the world increasingly recognizes the critical interactions between energy generation and sustainable ecosystems for air, land and water.We anticipate seeing these new visions for PV impact its growth in the future.

APPENDIX
The sources of the data reported in Figs.1-3 were described in detail in the Appendix of Version 1 [3].The same sources, as enumerated in Section I, were consulted for Version 3, following the release of the 72nd Statistical Review of World Energy on June 26, 2023.Updated data from other sources were downloaded July 1 or 2, 2023.
As previously noted, many of these sources revise their data in retrospect, as new information comes in and/or reporting accuracy increases.Where updated tabulated data are available for download, we have incorporated updates from previous years into our Version  EIA fossil fuel capacity data for 2022 are not yet available, and the Statistical Review of World Energy does not include fossil capacity information, requiring the use of additional sources to create the 2022 pie chart in Fig. 2(c).Because of a change in data presented in the REN21 documents, this year we used data from the Global Energy Monitor organization [18].Data in their Global Coal Plant and Global Gas Plant trackers were used to estimate the change in fossil capacity from 2021 to the end of 2022.

Manuscript received 21
August 2023; accepted 22 August 2023.Date of publication 8 September 2023; date of current version 7 November 2023.This work was supported by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Grant DE-AC36-08GO28308.(Corresponding author: Sarah R. Kurtz.)

Fig. 1 .
Fig. 1.(a) Annual electricity generation and (b) electricity generating capacity.Data are tabulated in Tables I and II with lines for the bolded data and open circles for the other sources.

Fig. 2 .
Fig. 2. (a) Pie charts showing global share of electricity generation by technology for the indicated years.Data taken from Tables I and VIII and summarized in Tables III-VII (see appendix for details).The "other" category includes biomass and geothermal.(b).Pie charts showing global share of electricity-generation capacity by technology for the indicated years.Data taken from Tables II and IX and summarized in Tables III-VII (see appendix for details).(c).Pie charts showing global share of net expansions of electricity-generation capacity by technology for the indicated years.Data taken from Tables II and IX and summarized in Tables III-VII (see appendix for details).

Fig. 1
Fig.1shows yearly global electricity generation and generating capacity, from 1990 to 2022.Source data are presented in Tables I and II, respectively.Data from the Statistical Review of World Energy, 72nd edition[1], are indicated in Fig.1(a) by solid lines, with open circles used to mark other data sources as indicated.For Fig.1(b), solid lines represent the data in bold in TableII, with open circles used to mark the other data sources.Data source variations, of interest for detailed understanding and analysis, are seen in the tabulated data, but are not significant when plotted on the logarithmic scale over time.Electricity generation [see Fig.1(a)], a measure of energy provided, is presented in TWh, where 1 TWh = 3.6 x 10 15 J. Installed nameplate capacity [see Fig.1(b)] is the rated output of a generator or other electric power production equipment under specific conditions designated by the manufacturer.The "capacity factor" is the ratio of the actual output of a system or collection of systems under true operating conditions (reflecting, e.g., variable resource, facility downtime, performance variations, large scale climate effects, etc.) and the output of (a)-(c), we plot global data for the past five years (2018-2022) for: fraction of electricity generation by source; fraction of current electricity generating capacity; and fraction of net expansions of electricity generating capacity for the given year.Data for fossil, nuclear, and hydro are drawn from TableIand are summarized by year in Tables III -VII.Data for wind, solar and other technologies are drawn from Table VIII and also summarized in Tables III-VII, with the electricity generation data in Fig.2(a) taken from Tables I and VIII and the electricitygeneration capacity data in Fig.2(b) taken from TablesII and IX.The net expansions of the electricity-generating capacity data in Fig.2(c) are obtained by subtracting the data in Fig.2(b)for each year from the following year.The choice of data sets to use for Fig.2and tabulated in Tables III-VII is detailed in Appendix.Some values in Tables III-VII are not directly available and were calculated from multiple source data as described in Appendix.Data sources used for the most recent year pie charts (2022) are driven in part by the time frames in which various sources release new data.

Fig. 3 .
Fig. 3. (a) Annual electricity generation and (b) electricity generating capacity by fuel.Data are tabulated in Tables VIII and IX (see appendix) with lines for the bolded data and open circles for the other sources.

Fig. 4 .
Fig. 4. Global pumped-hydro storage capacity (EIA, thick black line) and annual changes in storage capacity.The dashed black line indicates the differences in thick black line, while the dashed red line indicates the additions of grid-scale batteries as reported by the IEA.[11].

Fig. 5 .
Fig. 5. Electricity delivered by grid-scale storage assets in the United States, as reported by the EIA 923.[12].
VI. CONCLUSION2022 was a globally recognized milestone year in PV due to the achievement and then rapid eclipse of the 1 TW benchmark for solar capacity.Total global electricity generation from PV of 1323 TWh, with ∼ 263 TWh of that added in 2022, reflected a ∼25% increase in just one year.Despite lingering supply chain and tariff/trade issues around the globe, PV advanced dramatically in 2022, contributing 56% of newly installed global electricity generating capacity.
3 tables.The data presented in Figs.1-3 are tabulated in Tables I-IX.The selection of data for Tables III-VI has little effect on the creation of Fig. 2(a) and (b) but can have a greater effect on the appearance of Fig. 2(c).The electricity data in Fig. 2(a) and Tables III-VII were taken from The Statistical Review of World Energy.The capacity data in Fig. 2(b) andTable II used WNA data for nuclear, Statistical Review of World Energy data for wind and solar and REN21 data for hydro, biomass and geothermal.

TABLE I GLOBAL
ELECTRICITY GENERATION BY TECHNOLOGY CATEGORY (TWH FOR INDICATED YEAR)

TABLE II GLOBAL
ELECTRICITY GENERATION CAPACITY BY TECHNOLOGY CATEGORY (GW)

TABLE III GLOBAL
2018 DATA SUMMARY FOR CREATING PIE CHARTS IN FIG. 2 TABLE IV GLOBAL 2019 DATA SUMMARY FOR CREATING PIE CHARTS IN FIG. 2 TABLE V GLOBAL 2020 DATA SUMMARY FOR CREATING PIE CHARTS IN FIG. 2 TABLE VI GLOBAL DATA SUMMARY FOR CREATING PIE CHARTS IN FIG.

TABLE GLOBAL 2022
DATA SUMMARY FOR CREATING PIE CHARTS IN FIG. 2 TABLE VIII GLOBAL ELECTRICITY GENERATION BY FUEL (TWH FOR INDICATED YEAR); TOTAL, NUCLEAR, AND HYDRO ARE TABULATED IN TABLE I(A)