Solar Powered Airconditioning

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Solar Powered Air Conditioning

for Elderly, Low Income

Houstonians

Robert L. Howard, Jr., Ph.D.

National Society of Black Engineers

Houston Space Chapter


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August, 2003Chapter Technology Seminar

NSBEHouston Space Chapter

Introduction

The

Need

Air conditioning can be as high as 25-40% of

a households annual energy costsMany low-income residents cannot afford this

and go without air conditioning

60,000 homes in Houston without power in

2001; only 14,443 in all of Texas receivedassistance

Senior citizens accounted for 14 out of 20heat-related deaths in Houston in 2001


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Introduction

The

Need

CDC reports fans are useless at temperatures

above 90 deg F with humidity above 35% Spur movement of hot, humid air

Causes increased heat stressaccelerates body

hearting and raises internal body temperature

Essentially turns room into convection oven

Should not be used for preventing heat-related

illness in areas of high humidity


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Introduction

Problem persists despite local efforts tohelp

Window air conditioners donated, but wiringin many homes cannot handle added load

1998 fatality: widower had turned off airconditioner to save money

Houston libraries and multipurpose centersopen as cooling centers, but inaccessible tosome: elderly less mobile, afraid to leavehome, lack transportation


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Introduction

Exce

llent opportunity for NSBE and

NASA to come together in mutual

fulfillment of chartersNSBE-Houston Space Chapter can make a

positive impact by installing solar powered

air conditioners in as many elderly, lowincome households as possible


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Introduction

Provides a cool zone within homeelderlydo not have to leave homes to be safe

Does not interfere with limited housewiring

Will not increase household electric bill

Technology available off the shelf, but notaccessible to these communitiescost andunfamiliarity; we will bring it to them


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Introduction

Harmony of NSBE and NASA objectives NASA vision is to improve life here, to extend life

there, to find life beyond.

NSBE mission is to increase the number of culturallyresponsible Black engineers who excel academically,succeed professionally, and positively impact thecommunity

Solar power system improves life here in aculturally responsible way that positively impactsthe community

If we dont do it, who will?


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Introduction

Service project may well save lives; at

minimum it will increase the comfort of

our elderlyAlso benefits chapter members by

providing hands-on technical experience

many will not encounter in day-to-day jobresponsibilities


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Brief Survey of Solar Electric

Power

More than just a set of solar panels

Variety of components required for proper

functioning

Photovoltaic Panel

Three basic types: single crystal silicon,

polycrystal silicon, and thin film/amorphous

Convert sunlight directly into DC electricity


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Power

Inverter

Converts DC electricity into AC electricity

Most home appliances require AC powerBattery

Provide energy storage for use when solar panels

cannot receive sunlight

Also supplement panels to smooth power level Most are Lead-acid (30% sulfuric acid)

Absorbed Glass Mat (AGM) type recommended

requires no maintenance and cannot leak


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Power

Charge Controller

Used in any solar power system that includes

batteriesBlocks reverse current (solar panels draining

batteries) and prevents battery overcharge

May also prevent battery overdischarge,protect from electrical overload, and display

battery status and flow of power


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Power

Power Outlets and Wiring

Proper gauge wiring essential to avoid poor

performance of appliances and possible firerisks

Power outlets sometimes include circuitprotection

Frame/StructureHold solar panels in place; roof or pole

mounts; some pole mounts track sun


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Overview of Mars Testbed Solar

Recharge Station

Some in-house JSC experience with solarpower systems

Environmental Office (COD) and AdvancedEVA Group built a solar recharge station as

part of a Mars testbed activity

Used commercially available components

from Solarcraft (Stafford, TX)Purpose was to demonstrate how state-of-the-

art technology can improve life on earth aswell as explore space


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Recharge Station


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Recharge Station

Reads like a prelude to this project

HSC will seek to tap into their expertise

and possibly their relationship withSolarcraft

Will also seek to coordinate with MOD

and Engineering Directorate organizationsinvolved with solar power


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System

Two main options exist:

Daylight-only system (no batteries)

Simpler, significantly less expensive Offers no cooling between sunset and dawn

Continuously operating system (requiresbatteries)

Provides constant temperature More expensive and complex

Presentation will explore both options, but willnot choose between them


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System

Daylight-only Configuration


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System

Continuous Operation Configuration


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Subsystem Data

In order to conduct a preliminary sizing,

data was compiled on commercially

available solar power subsystems and airconditioning units

Voltage, wattage, amperage, BTU cooling

capacity, price, vendor, etc.


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Preliminary System Sizing

Complete solar-powered air conditioningsystem sized based on current vendorprices

Should not be construed as an exactspecification of what the system will looklike or cost

Prices, component availability subject tochange

Chapter may decide to construct items in-house rather than use commercial equipment


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Should be viewed as a ballpark estimate

Both options (daytime vs. continuous)

sized

For simplicity, continuous system assumes:

12 hours charge time; 10 hours discharge time

Overcast conditions not modeled in this

analysis


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Both options assume cooling for a 300 to350 square foot area, which includes akitchen

Rule of thumb suggests 8,000 BTU airconditioner for this square footage, withadditional 4,000 BTU to account for

kitchen heatSelected 1140 W Kenmore 12,300 BTU

Multi-Room Air Conditioner


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Option 1 (Daytime-only)

Photovoltaic Panel

SAPC-165 multicrystalline module

156 W per module, $612Total of seven required, for cost of $4284

Panel Mounting

UTRF64 Passive Tracking MountTracks sun passively (no electric power)

Holds all seven SAPC-165, costs $989


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Inverter

Sized based on power generated

Using Powerstar 1300 inverter, but requiresDC Converter

Powerstar operates at 12 V, photovoltaic panels

operate at 24 V

Powerstar costs $540, converter costs $285 for

total of $825.00


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Wiring and Receptacle

Length will vary with each house; impossible

to specify in advanceAssuming generic value of $200

Total cost for Option 1: $6,698

One unresolved concern: uneven powersupply levels may damage air conditioner

Chapter will need to resolve concern


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August, 2003Chapter Technology SeminarNSBEHouston Space Chapter


Option 2 (Continuous Operation)

Batteries

AGM batteries chosen - 12V Concorde PVX-

2120L offers the best value (2520 W-hrs)Six batteries required to meet power goal

Cost $304.95 each, for a total of $1,829.70

Photovoltaic Panels

15 SAPC-165 providing 2400W at $5,999.85

Inverters

Two Powerstar 1300 Inverters at $1,080


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Option 2 (Continuous Operation)

Charge Controller

Trace C35: three units usedone for every

two batteriesTotal cost: $337.05

Tracking Mounts

Two UTRF64 tracking mounts used at cost of$1,978

Total cost for Option 2: $11,819.64


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Difference in price visually shows why

Option 1 remains a preferred choice

$6,698 vs. $11,819.64

Limitations in Option 1 must be solved

before it can be considered valid, however


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Fundraising

Chapter cannot pay for this project from

dues, shirt sales, and dinners

Will seek to partner with JSC, contractors,and solar power companies in hopes of

equipment donations

Will pursue grants and contracts fromfoundations, government agencies,

businesses, nonprofits, etc.


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Fundraising

Need chapter members to join Finance

Zone to help Marlo in this area

Need new members from businessdirectorates within JSC and contractors,

especially B, H, and L mail codes


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Engineering Roadmap

Thispaper is only a first step, not acomplete analysis

Need for additional studies - engineeringwork continues

Deepen understanding of solar power systems

Resolve outstanding technical issues

Generate Finalized specifications

Safety reviews

Implementation procedures


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Engineering Roadmap

Need for electrical engineers in the chapter

to step up and get involved

New members especially needed fromDF7, DT4, EC, EP, and JA13

Room for other chapter members

engineers and non-engineers to contribute


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Engineering Roadmap

Paperstudies likely to continue through fall and

into early spring

Build hardware experience prior to assemblingair conditioner units

Conduct series of smaller, less expensive solar

projects (e.g. solar fans, other low wattage devices)

Side benefit: many of these may have outreach uses

Goal: first operational unit completed in time for

summer 2004


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Candidate Selection

No mechanism in place yet to selectrecipientsmust be accomplished prior to

first deliveryChurches, United Way, etc. work routinely

with the types of elderly we wish to serve

Coordinating with such organizations willhelp us to identify responsible elderly withgenuine need


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Conclusion

We cant help everyone suffering in Houston

We will make a difference

We will pioneer a roadmap other organizationscan follow

Enhance image of NASA, NSBE, contractors,

partners

Gain sense of satisfactionwe will have used

our skills to change the lives of people


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August 2003NSBE Houston Space Chapter

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Solar Powered Airconditioning