Basic Understanding of Solar Photovoltaic (PV) Arrays - Solar PV Awareness.pdf · Presented By:...

Basic Understanding of Solar Photovoltaic (PV) Arrays

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Presented To: WEF Operators Day February 4, 2014

Presented By: Sachit Verma, MS Program Manager - Energy NOVA Consultants, Inc.

NOVA Consultants, Inc. 21580 Novi Road, Suite 300

Novi, Michigan 48375

(248) 347-3512 • FAX (248) 347-4152

Professional Engineering, Environmental, and Energy Services

Purpose

To provide a basic understanding of wind and solar photovoltaic

(PV) arrays and the benefits of adding alternate energy sources.

2 NOVA Consultants, Inc. 248-347-3512

Solar vs. Wind Energy 1. Ground-mount arrays in open spaces

2. Roof mount arrays on top of water reservoirs

3. Wind favors wide open rural areas. Most water/wastewater sites are near urban areas, so wind resource may be limited

4. Solar resource is impartial and uniform across terrain

5. Municipal permitting for solar arrays may be relatively easier than for wind turbines

6. Small wind turbines are not well proven, while large wind turbines are more suitable for wide open spaces (delivery as well as installation)

7. Solar arrays are very scalable. Larger array only needs more modules, not larger or different modules. Array can be easily expanded in future.

8. Large turbines have issues – shadow flicker on nearby homes as blades turn in the sunlight, bird hits, ice catapult (in cold climates), constant humming noise etc.

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Understanding Demand and Supply 1. Solar power generation peaks at noon

– Prime generation window is 9:00 am to 3:00 pm

– Can offset high peak utility rates (Peak demand shaving) since peak generation is in sync with peak demand

2. Wind power generation peaks at late night/early morning

– During high electric demand days (hot summer afternoons), there is no wind blowing

– Often large turbines have to be shut down at night since there is too little demand, unless energy is stored (Ludington Pumped Storage is ideal use of wind energy)

– Baseload fossil fuel generators have to run anyway.

Ideal scenario

1. With low natural gas prices, use it for baseload

2. Use solar peak load

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Solar PV Array Awareness

NOVA Consultants, Inc. 248-347-3512 5

Typical Renewable Energy Services

Renewable Energy Integration:

– Residential PV (3.4 kW - 20 kW)

– Commercial PV (14 kW – 1200 kW)

– Industrial PV – 20 projects (14 MW)

– Landfill gas – 7 projects (1.5 Tbtu)

Excellence in Business Services 6

(Building Loads

Common Solar PV Support Structures


Ground Mount - Fixed Roof Mount

Carport Ground Mount - Trackers

Voltage Output vs. Temperature

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Current Output vs. Irradiance

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Pros & Cons of Solar PV Arrays


Solar PV – Pros • PV Modules will last 30+ years

• PV Module Materials and Workmanship Limited Warranties are 5+ years

• PV module output performance is guaranteed for 20+ years (Most are 90% for 10 years and 80% for 25 years)

• Inverter warranties are 5-10 years

• Very Low Maintenance – keep it clean

• No moving parts

• Doesn’t require huge concrete foundation

• Can be mounted on ground, pole, awning, roof, etc.

• Feed-In Tariffs make investment very good

• Net metering helps the business model

• Prices are dropping, now at an all-time low

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Solar PV - Cons

• Mindset - “Michigan Winter” climate with low sun level

• Performance drops in cloudy weather or partial shading

• Partial shading has a large effect

• Panels take up a large space

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Financial Structure

– For-profit utilities can take advantage of tax incentives, and own the renewable energy assets outright.

– Many municipal utilities cannot take advantage of tax incentives since they may be non-profit organizations.

– Need to partner with a for-profit third party to leverage tax benefits and reduce costs

– Third party owns the asset, and claims depreciation and tax incentives

– Use power purchase agreement (PPA) to buy energy from third party owner.

– Can transfer ownership to utility at fair market value after 5 years

– Third party owner responsible for O&M

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Importance of Good Solar PV Array Design and Installation


• PV solar modules generate power all the time when exposed to light

• Broken or cracked PV solar modules can short circuit

• 12 to 13 modules make a DC strings that generate 350 to 550 VDC, some systems at 1000 VDC

• Broken (disconnected) grounding system

• Tripping hazards – terrain, conduit runs

• Site access and walkways for emergencies

• Back-feed from DC strings due to common bus

• Arching PV systems on roof tops due to poor design

Health & Safety Risks

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Racking PV Solar

Modules

Combiner

Boxes Inverter(s)

AC Service

Disconnect Meter

NOVA Consultants, Inc. 248-347-3512

Strategy

• Design for safety

– Safe construction

– Safe Oper. & Maintenance

– Safe Emergency Response

• Qualified Contractor

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Mitigating Health & Safety Risks

Common Start-up

• Safe project execution

• Approved final inspections

• Safe system start-up

• Safe system operation

Common Construction

• Site Safety Plan

• Training and awareness

• Construction plan

• Design Review

• Site Commissioning

Common Design

• Defined scope

• Standards – NEC; NFPA

• Shade and structure analysis

• Quality Checks

• Constructability and access

NOVA Consultants, Inc. 248-347-3512

Safety Solar Array

– Panels make DC – not too many electricians familiar with it

– Panel is live as long as there is light. Cannot turn it off.

– Roof mount needs structural analysis of roof for anticipated load

– Firefighters not fully aware of PV array hazards

– Proper location of disconnects to isolate array

Wind Turbine

– Blade failure

– Ice catapult (Blade tip speed can be very high)

– Lightning strikes

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Analysis • Engineering

– Solar Engineering

• Shade Analysis

• Racking – Efficiency/Production RECs

– Civil /Structural Engineering

– Electrical Engineering

– Interconnection Diagrams & Approval

• Municipality Requirements/Permits


Ensuring Quality Design

• Common Design - Quality Checks – Perform 3-D shade analysis

– Perform structural analysis or geotechnical analysis

– Wire ampacity and fuse sizes taking into considerations module type, string configuration, potential cold temperature

– Roof access, clearance to roof edge, walkways, space around heat and smoke vents to support O&M and emergency responders

– Utilize arc fault combiner boxes for roof mount units or when DC circuits enter a building.

– Ensure all metallic parts are bonded and grounded properly

– Design wireway / conduit runs and ground cover to avoid trip hazards

– Design wireways to properly support DC strings and connectors and avoid contact with the roof or metallic frames (avoid damaging the insulation).


Ensuring Quality Installation

• Common Construction Practices – Communicate the site safety plan, with project specific requirements

– Execute a construction plan on sequence of installation and required quality checks to document compliance with the design and specifications.

– Work as though all wires and connections are energized

– Execute and document detailed commissioning of the system

• DC string voltage and polarity

• Grounding conductivity

• Inverter start-up and anti-island test

• Current test on DC strings

• Infrared scanned image of modules, connectors, combiner boxes, etc.


Alternate Energy for Utilities Levels of engagement 1. No alternate energy – probably majority of sites

2. Fully grid-tied alternate energy

• Alternate energy supplements utility grid power

• Need back-up generators in event of grid failure

• Anti-island safety provision shuts down solar/wind during grid failure

3. Micro-grid

• Wind/solar systems continue operation in isolation from grid during grid failure

• Return to grid-tied operation when grid power restored

• Battery storage and/or generators to smooth solar/wind fluctuations

4. Off-grid

• Wind/solar with battery backup for remote locations

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Recent Examples of grid failure

1. Hurricane Katrina

2. Superstorm Sandy

3. Snowstorms in winter 2013-2014

• Alternate energy is best suited to supplement grid power or conventional backup (generator) or battery storage

• Extends fuel life

• Generation smoothing as solar/wind power fluctuates with weather

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Solar Arrays on Water/Wastewater Tanks Lansing Board of Water and Light

– 50 kW array on water reservoir

– Ballasted system (no penetrations into tank roof)

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Solar Arrays on Water/Wastewater Tanks Wyandotte Municipal Services

– 162 kW array on water treatment tank

– 50 kW array on water reservoir

– Ballasted system (no penetrations into tank roof)

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Utilize an Established EPC Firm

• Scio Twp (ground w/ trackers) 60 kW

• Ford Wayne Assm (ground) 502 kW

• MCCC (ground) 513 kW

• BCBS (roof top) 219 kW

• GM Hamtramck (ground) 516 kW

• DTE-TDC (ground) 391 kW

• Mercy H.S. (roof top) 402 kW

• Warren C.S. (roof top) 189 kW

• DTE-HQ (carport) 83 kW

• GM Orion (ground) 345 kW

• Wil Le Farms (ground) 484 kW

• HCMP (ground) 495 kW

• UM-NCRC (ground) 430 kW

• UM Fuller Road (trackers) 220 kW

• Hartland School (ground) 514 kW

• St. Clair RESA 517 kW

• Riopelle Farms 514 kW

• IHM Sisters (ground) 518 kW

• Leipprandt Orchards 511 kW

• Bay City – MDNR (ground) 10 kW

• Huntington Woods (ground) 20 kW

• MDOT (carport) 100 kW

• Wyandotte M.S. (roof top) 212 kW

• Amerman Elementary 3 kW

• NOVA Office (roof) 14 kW

• Residential 1 (roof) 4 kW

• Residential 2 (roof) 6 kW

• OLHSA Residential 1 (roof) 2 kW

• OLHSA Residential 2 (roof) 2 kW

• OLHSA PV Solar (ground) 135 kW

• Totowa, NJ (design only) 1,200 kW

NOVA - Providing Excellence in Engineering, Energy, and Environmental Services 26

NOVA Solar Experience – Commercial/Residential

• Size: 3.7 kW to 14 kW

• Panel Technology:

– Thin film

– Crystalline

• Installation: 2010


NOVA Solar Experience Scio Township

• Size: 60 kW total – 13 kW on trackers, 47 kW fixed

• Inverters: (2) Solectria PVI 1300, (2) PVI 1500

• Solar Panels: 270 Sharp 224 W

• Date: 8/2010

• Scope: Engineering, Procurement and Construction


NOVA Solar Experience Ford Motor Company

• Size: 500 kW - Ground Mount

• Inverters: (2) Satcon PowerGate Plus 250 kW

• Solar Panels: 2184 Schott Poly 230W

• Date: 1/2011



NOVA Solar Experience Monroe County Community College

• Size: 500 kW - Ground Mount



• Date: 2/2011



NOVA Solar Experience Blue Cross Blue Shield of Michigan

• Size: 220 kW – Roof Mount



• Date: 7/2011



Tech Evaluation & Design

Site Evaluation

Completed Projects

Installation

Conclusion

• For most utility sites, solar is probably more suitable than wind for onsite generation.

• Ensure sound solar array with proper design and installation plan.

• Solar PV contracts can be structured in many was to ensure the customer requirements are met.

• Compared to fossil fuel power generation, solar PV power is good for your health with no carbon, sulfur, mercury, or particulate emissions.


THANK YOU!

Sachit Verma NOVA Consultants, Inc.

21580 Novi Rd. – Suite 300

Novi, MI 48375

(248) 347-3512

www.novaconsultants.com

Basic Understanding of Solar Photovoltaic (PV) Arrays - Solar PV Awareness.pdf · Presented By:...

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