Technical Advances in the Off-Grid Solar Sector

Transcription

1 Technical Advances in the Off-Grid Solar Sector Dr. Arne Jacobson Director, Schatz Energy Research Center Technical Lead, Lighting Global Quality Assurance January 22, 2018

2 Key Off-Grid Solar Technology Trends Performance Gains in LED efficacy have offered the largest opportunity for performance and price improvements for solar lamps Appliance efficiency is similarly important for solar home systems, although the effect is not as dramatic Durability The transition to lithium batteries (especially LiFePO 4 ) is a key factor for improved durability for small products, and these batteries are used increasingly in larger products Affordability and Productive Applications Innovation in PAYG technology has expanded access through improved affordability PAYG technology can also be used to expand access to productive applications Longevity Aftersales service (warranty, repairs, etc.) plays a key role in product longevity; more innovation is needed in this area

3 Performance and Durability Gains for Off-Grid Solar LEDs and product performance LED efficacy gains have been especially important for pico-solar products (but improvements are expected to taper off by about 2025) LEDs have also improved with respect to price, durability, and quality Solar products have benefitted from improved battery durability and falling PV prices

4 LED Efficacy Trend for LG Tested Off-Grid Solar Products Lumen Efficacy (lm/w) The median lumen efficacy for pico-solar products tested by Lighting Global has increased by 60% since The highest efficacy products now exceed 160 lumens/watt

5 Efficacy Trends for Commercial LED Packages LED efficacy gains are expected to begin leveling off at about 250 lm/w by around After that, performance gains for offgrid solar lighting won t be as easy or fast. Source: U.S. DOE, Notes: PC-LED = Phosphor Converter LED

6 2000 hour lumen maintenance test results LED Durability Trend for LG Tested Off-Grid Solar Products LED durability has increased, and most quality assured products now easily achieve lumen maintenance values that exceed 95% of original light output after 2000 hours

7 LED Color Temperature Trend for LG Tested Products The color temperature trend has declined modestly over the past five years, indicating a trend toward warmer light. The current lower bound for correlated color temperature (CCT) values for pico-solar products is around 4000 K

8 Off-Grid Solar Products Are Shifting Toward Lithium Batteries The shift toward lithium batteries is nearly complete for quality assured pico-solar products An increasing number of SHS products are also using lithium batteries as larger lithium batteries become more affordable Battery type for pico-solar products tested by LG QA Off-Grid Electric: M-Power M120 SHS w/43 W solar module and 141 Wh LiFePO 4 battery

9 Battery Durability Test Trend for LG Tested Products Battery durability has increased with a shift toward lithium-based batteries The cycle life for lithium batteries can be cycles or more, while sealed lead acid batteries often last cycles

10 Pico-Solar Product Cost Trend Normalized to Constant Level of Service Provision (100 lumens of light, 4 hours/day) Note: Results are based on the average performance for relevant metrics for LG tested picosolar products during the respective years. The reported values are for the estimated retail price. The cost to deliver a constant level of lighting service declined by 67% from 2012 to 2018, mainly due to gains in lumen efficacy

11 Super-Efficiency is also a Key Driver for SHS Cost Super-efficient appliances can help reduce the cost of solar home systems for a given level of service delivery because smaller loads allow for a smaller solar module and battery (results are based on cost and performance data from 2016)

12 Energy requirements for phone charging loads will increase as smart phones become more common Smart phones are increasingly common in rural areas Smart phones can consume 3 to 5+ times more energy per charge event than basic mobile phones For off-grid solar systems, the energy requirements for mobile device charging are going up while efficiency is reducing energy demand for other appliance types Some off-grid solar products that advertise mobile phone charging capability cannot effectively charge smart phones

13 PAYG Innovation is Spreading from Household Applications to Product Applications and Beyond Flexible financing methods such as PAYG can make offgrid solar more affordable While PAYG is widely used for household systems, some companies are experimenting use of PAYG to sell solar products for productive applications Solar water pumping system deployed by Simusolar in a PAYG pilot in Tanzania.

14 More Innovation is Needed to Enable Effective Aftersales Service Effective warranty and aftersales service are crucial for ensuring product reliability and longevity However, delivering these services efficiently in the last mile is very challenging

15 More Innovation is Needed to Enable Effective Aftersales Service Many technicians have the right skills, but they often lack product-specific training and access to technical information and spare parts Some product designs inhibit product repair by rural technicians (e.g. tamper-proof PAYG systems)

16 Summary of Key Points Performance Gains in LED efficacy have offered the largest opportunity for performance and price improvements for solar lamps Appliance efficiency is similarly important for solar home systems, although the effect is not as dramatic Durability The transition to lithium batteries (especially LiFePO 4 ) is a key factor for improved durability for small products, and these batteries are used increasingly in larger products Affordability and Productive Applications Innovation in PAYG technology has expanded access through improved affordability PAYG technology can also be used to expand access to productive applications Longevity Aftersales service (warranty, repairs, etc.) plays a key role in product longevity; more innovation is needed in this area

17 Thank You! Arne Jacobson, Ph.D. Director, Schatz Energy Research Center Technical Lead, Lighting Global QA Humboldt State University

18 Annex Slides

19 LED Color Rendering Index (CRI) for LG Tested Products CRI has increased modestly over the past five years, indicating improved color rendering

20 PV Module Efficiency Trend for LG Tested Products with Separate Modules

21 PV Module Efficiency Trend for LG Tested Products with Integrated Modules

22 Battery Charge- Discharge Efficiency Trend for LG Tested Products

23 Charging Circuit Efficiency Trend for LG Tested Products

24 Solar Operating Efficiency Trend for LG Tested Products Note: The solar operating efficiency is the ratio between the actual amount of solar electricity generated by the module and the maximum that could be generated with an optimal control scheme.

25 Variability of Test Results Across All LG Tested Products (QTM) The observed variability is a function of performance variations among the six tested samples of each product model and the measurement uncertainty for the test

26 Variability of Test Results Across All LG Tested Products (QTM) The observed variability is a function of performance variations among the six tested samples of each product model and the measurement uncertainty for the test The variability among tested samples has declined substantially for some metrics (e.g. lumen maintenance). The test measurement variability for lumen maintenance is expected to be relatively stable, so the reduction in observed trend suggests reduced unit to unit variability that may be due to tighter manufacturing tolerances.

27 Variability of Test Results Across All LG Tested Products (QTM) The observed variability is a function of performance variations among the six tested samples of each product model and the measurement uncertainty for the test The variability for other metrics (e.g. daily solar run time) remains relatively high due to a combination of measurement uncertainty and unit to unit variability.