1. Hannah Peterson October 2016
EMI Solar Power Design
Hannah Peterson
October 2016

2. Sign In for Continuing Education
AIA members:
EMI is an AIA Approved Provider and this course has been approved
EMI will report credit and attendance to AIA
This course will not be used to promote or market any products or services
Everyone:
EMI will you a certificate of completion within 10 business days
Required for courses that are approved for AIA continuing education.

3. Welcome! Hannah Peterson Volunteer Electrical Engineer for EMI
(also…worship leading, international students, Japanese)
5 EMI projects in Africa and Middle East
Prior to EMI: 10 years
US Air Force
Cummins Diesel Generators
Solar Power

4. Course Description
This course will equip the designer with a basic knowledge of solar power systems and provide the knowledge and resources to compare available power sources and select the appropriate combination for the application.

5. Learning Objectives
Learning Objective 1: Participants will understand terminology frequently used in the Solar Power Industry. Learning Objective 2: Participants will understand the differences between the types of solar modules available. Learning Objective 3: Participants will understand the components and function of different types of solar power systems. Learning Objective 4: Participants will be able to understand the factors that impact the cost of solar, diesel, and utility power generation and use an EMI tool to select the best combination of power sources for the application.

6. Overview
Definitions
Module Types
System Types
Cost Analysis

7. definitions

8. Definitions Solar modules
A lot of different shapes, sizes, and colors. One single unit of photovoltaic cells often with a junction box and sometimes with an inverter included (AC modules). This presentation covers solar power (electricity) and not solar thermal (water) panels

9. Definitions
Solar Array

10. Definitions
Photovoltaic = PV = Solar Power

11. Definitions How do we measure solar energy? Solar irradiance W/m²
Irradiation (insolation) Wh/m^2, integral or area under the curve
Jagged sections are times with some cloud or other partial shading. Notice the shape of the curve. This is the same shape the output of the solar power will be. Notice the time range: about 6am to 6pm. The majority of the solar power occurs between 8am and 4pm. So it is particularly important to avoid any shading during these hours.

12. units=hours= 𝑊ℎ/𝑚^2 𝑊/𝑚^2
Definitions
Peak sun hours or sun hours:
𝐼𝑛𝑠𝑜𝑙𝑎𝑡𝑖𝑜𝑛 1000
units=hours= 𝑊ℎ/𝑚^2 𝑊/𝑚^2

13. Definitions
Map of average annual insolation

14. Definitions STC: standard test conditions
25°C, 1000 W/m^2, Air Mass 1.5
NOTC: Nominal Operating Cell Temperature test conditions
45 (±3)°C, 800 W/m^2, Air Mass 1.5
The main rating you see on labels and datasheets for each solar module are at standard test conditions (STC).

15. Definitions
Part of a typical solar module label and a graph showing where these values come from. By changing the load applied the voltage is controlled and swept across the range: 0V to open circuit voltage. (Use slide animation as explain the following) Notice where Isc: short circuit current, at V= 0 and Voc : open circuit voltage, at I=0 fall on the curve. Also notice where the power output is maximum. This is called the “maximum power point”. Inverters used to convert the DC power from a solar array into AC power constantly operate the total array at this point using “MPPT” or maximum power point tracking software. The power output shifts based on temperature and irradiance. Irradiance impacts current. Temperature impacts voltage.

16. module types

17. Module Types Polycrystalline “Poly” Monocrystalline “Mono”
How to tell it is crystalline: Will see typically see conductive ribbons stretched across individual cells.
How to tell it is mono: “Honeycomb” look or “small diamonds”
60 is standard for residential systems. 72 are larger and more common in larger commercial/utility scale systems. 96 cell are more rare, but are a standard size.
Most common materials: glass front, metal frame, EVA backsheet, junction box on back with MC4 or Tyco connectors
Although mono is highest efficiency available it is not by much and there are cheaper mono that are lower efficiency than the top poly modules so it really often comes down to aesthethic preference.
Highest output/m^2, Most common
Standard sizes: 60, 72, 96 cell

18. Module Types
Thin Film
Can be manufactured on rigid or flexible materials.
Currently less common than crystalline due to price, efficiency, and availability.

19. Module Types
AC Modules
Comes with microinverter on each module

20. system types

21. System Types Off-Grid, Self Regulating Systems - + Load Batteries
Solar Modules

22. System Types Off-Grid, Stand-Alone Inverter Charge Controller AC Loads+
Genset
Solar Modules
Batteries

23. System Types Utility-Interactive and/or Genset Interactive
Solar Modules
Inverter
Electric
Panel
ATS
Utility
Genset

24. System Types Genset Wet Stacking
If operate below around 30% of rated load for long periods
Unburned fuel comes out of the combustion chamber

25. System Types Genset Wet Stacking Results: Fouled injectors
Buildup on exhaust valves, turbo charger, and exhaust
Loss of engine performance
Premature engine wear due to degraded oil seals

26. System Types Genset Wet Stacking
If caught before this stage may be reversible
This was a genset that had to be run at low loads due to necessity from a main electrical buss failure.

27. System Types Genset Interactive
Ballpark of $6k for Fronius controls. Ballpark of $20k for SMA version which is much more sophisticated.

28. System Types Genset Interactive
With simple controls and only diesel and solar power (no utility) on average <=15% of total power needed every day can be from solar power. This is why our cost analysis assumes 15%. Could be more based on timing of loads.
With more complex controls and multiple paralleled Gensets amount of power provided by solar power can be much higher.
Ballpark of $6k for Fronius controls. Ballpark of $20k for SMA version which is much more sophisticated.

29. System Types Genset Interactive: Time of use is important
Ballpark of $6k for Fronius controls. Ballpark of $20k for SMA version which is much more sophisticated.

30. System Types Grid-Interactive and Off-Grid, Bi-modal System
Main Electric Panel
Solar Modules
Charge Controller
Utility
Inverter
A GenSet can be included as well, but it is left out here for simplicity of the diagram
Critical Load Panel (AC)
Batteries

31. Cost analysis

32. Cost Analysis
Price of PV
$/Watt vs Year
From 1977
to 2013

33. Cost Analysis

34. Cost Analysis Major Factors:
Initial accessibility and cost of Utility Connection
Ongoing cost ($/kWh) and reliability of Utility Power
Insolation, amount of sun, at the location through the year.
Cost and availability of Diesel Fuel for a Generator
Local cost of Solar Power Installation ($/W)

35. Site Hourly Power Usage Solar System Assumptions Solar System Size
Generator
Assumptions
Utility
Assumptions
(Simply introduce the entire sheet and the organization, main categories, of the sheet using the slide animations. Point out that the yellow cells are data specific to the site that needs to be entered. No details or explanation at this point.)
Costs

36. Cost Analysis
(Simply introduce the entire sheet and the organization, main categories, of the sheet. No details or explanation.)

37. Cost Analysis Site Hourly Power Usage Battery Based
Existing site: Power Analyzer data maximum during simulated highest loading + Estimated new loads from load spreadsheet
New site: Calculated maximum loading expected based on load spreadsheet

38. Cost Analysis Site Hourly Power Usage
Utility and Generator Interactive
Existing site: Power Analyzer data averages per hour during simulated highest loading + Estimated new loads from load spreadsheet. If net metering available power bills may be used instead.

39. Cost Analysis Site Hourly Power Usage
Utility and Generator Interactive
New site: Educated conservative guess on hourly average loading based on load spreadsheet and expected time of use information from customer.

40. Cost Analysis Site Hourly Power Usage
Utility Availability as a % should be on average.
Generator logs and utility bills are best source
If there is no utility available you can set this to 0%
If utility outages are only at night a GenSet interactive system is not a good solution.

41. Cost Analysis Solar System Assumptions Batteries must be Deep Cycle
Most common deep cycle battery types:
AGMs (default) a type of valve regulated lead acid (VRLA)
Fluid filled lead acid
Lithium Ion
Tesla is claiming they will start offering their PowerWall Lithium batteries out of South Africa at a price that would make them competitive with AGMs.

42. Cost Analysis Solar System Assumptions Typical battery efficiencies:
AGMs (default) a type of valve regulated lead acid (VRLA) = can be up to 95-98%
Fluid filled lead acid = 85-95%
Lithium Ion = 99%
Battery replacement time must be whole number
Cycle life at DOD chosen divided by 365.
Tesla is claiming they will start offering their PowerWall Lithium batteries out of South Africa at a price that would make them competitive with AGMs.

43. Cost Analysis

44. Cost Analysis Solar System Assumptions
Battery specifications vary by type and manufacturer. Defaults in spreadsheet are for an AGM. Get a list of manufacturers and models available in the area and datasheets if possible.
Highlight the DOD of fluid filled lead acid and the life span of Lithium Ion. These are very important in total cost. Lead acid will look much cheaper than it really is in reality due to the low allowable depth of discharge. Lithium Ion will look much more expensive than it is in reality due to the long cycle life.

45. Cost Analysis
Example: Manufacturer - Trojan

46. Cycle life ratings Cost Analysis Manufacturer: Trojan 2750/365=7.5 yrs
600/365=
1.6 yrs
Range of lifespan for flooded lead acid from a single manufacturer at 50% DOD.

47. Cycle life ratings Cost Analysis Manufacturer: Trojan 1500/365=4 yrs
Range of life span for flooded lead acid at 80% DOD
300/365=
0.8 yr

48. Cost Analysis Solar System Assumptions Insolation:
Battery based system: Use average daily insolation for month with lowest amount of insolation. See EMI Design Guide Maps.
Utility or Generator Interactive: Use average daily insolation for the year.

49. Cost Analysis Solar System Assumptions Total System Efficiency
Typical real value from STC is around 70%
This may be too conservative in some cases like in a cold region at high altitude. If real data from a system in the region is available this can be adjusted to a higher value.

50. Cost Analysis Solar System Size
% of Current Daily Power covered by solar:
Adjust after all the other data is entered.
Try 100%, 50%, and 10% to start and observe impact.
The real value will mostly be based on initial installation cost constraints.

51. Cost Analysis Solar System Size Solar Module data:
Defaults of 260Watt and 1.6m^2 are for a standard 60 cell crystalline module.
Total area assumes flat roof-mounted arrays with no space for maintenance or fire fighting clearance and no spacing to avoid shading from obejects. This is the minimum area required.

52. Cost Analysis Generator Assumptions
Almost exclusively Diesel Generators
Google the price of fuel for the area before you leave.
Take photos of any diesel bills and ask for total cost of fuel per liter including all delivery fees. If way off from online value ask questions to make sure you are understanding correctly.

53. Cost Analysis Generator Assumptions
Divide 20,000 by the number of hours operated per year and round to nearest whole year.
20,000 hr lifetime is a ballpark.
Typically the diesels we see are not well maintained and fuel quality is poor.
Diesel fuel price is a much bigger driver on the financial case so a ballpark is adequate.

54. Cost Analysis Utility Assumptions
Ask for utility name and do an online search for electricity prices before you leave.
Get copies or photos of utility bills while on site.
If there are time of use charges or demand or power factor related pricing adjustments take note and use the average price.
If utility already to site enter “0” for distance.

55. Cost Analysis Equipment Costs
Visit local suppliers and talk with local utility
Leave as defaults if data not available

56. Cost Analysis

57. Cost Analysis

58. Cost Analysis Tool Output: Compares 7 Types of Solar Systems
(If possible go through each and have students describe components and how each system works as you draw out on a white board)

59. Cost Analysis In this case clear winners from year 3 forward:
End points and cross over points are key.

60. Cost Analysis So which is the right solution?
Answer: It depends. If this is a hospital then only the red one: utility plus utility & generator interactive solar.
If this is not a hospital and having power only when utility is available is ok then the purple wins with a 9 year payback period compared to utility alone.

61. Cost Analysis How much would adding solar save ?
If ok to not have power when utility down:
5¢/kWh; $139,000/25 years; $5500/year

62. Cost Analysis How much would adding solar save ?
If must have 100% power availability:
4¢/kWh; $57000/25 years; $5700/year