Installing Your Own Solar Power SystemStand-Alone and Grid-Tied Systems

By: Chad Ryan Weiss, Ecenaz Asku, and Kevin Neil Neidlinger

15Penn State University

Fig. 1 - Power Panel

MainDisconnect

Solar Panel InstallationsThe good thing about installing solar panels is that you don’t necessarily have to shut off power to your home until the very last part that is, hooking it up. That being said, safety does come first; so that’s where we’ll start.

Shutting off power to a circuit or your entire home

In the United States, most homes are powered by one phase of a three-phase 15 kilovolt (kV) distribution feeder (i.e. the power line). The power to the house is fed via three wires from the service transformer (xfm), two hot wires at 120 volts each and one neutral wire. These three wires are hooked up to the service entrance panel (a.k.a. the power panel). See Fig. 1

Most service entrance panels have a main on or off switch.Flipping this switch will turn off all the power to

your home. All of the other switches are attachedto individual circuits and can be shut off individually.The arrow here is pointing to the main disconnect switch. Flipping this will turn off the power to yourhome.

Your home’s electrical system is a composition of many individual electrical circuits served through a dedicated circuit breaker (CB). A CB is designed to isolate or disconnect its associated circuit should there be any fault in the circuit. CB’s vary in ratings: 10, 15 and 20 amps for 120 volt sources and 30 or 40 amps for 240 volt sources.

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Safety First!!!

Whenever you are working with any electrical system be sure to follow the basic standard safety procedures.

There are three key rules to practicing electrical safety:

1. Be sure you understand the basics of electricity, circuitry, and your own home’s wiring system;

2. Never work on any electrically “live” circuit. Be sure to shut off the power and test that it’s off.

To test whether a circuit is “live” or dead, just use a neon light indicator so that you don’t hurt yourself.

3. Know the hazards and risks of working with electrical systems and circuits.

These switches will turn off any particular circuit of your choosing and leave the rest of the house untouched.

So now that we’ve covered the basics of electrical safety in your home, we can begin to talk about installing, and getting to know your new solar system.

Knowing Your System

A solar-based system uses photovoltaic (PV) cells to convert light energy into electrical energy that can be stored or consumed on demand.

About the system

2159 watt grid-tie PV system using 10 PV panels at 215 watts.

Things to note

Most common type of solar PV system, Connected to electrical

grid allows the use of solar energy + electricity from the grid.

Solar panels send the excess electricity back to the grid.

Pros: Lowest initial cost (because there is no need for batteries and

charge controller) Lowest ongoing maintenance cost (no batteries to maintain

and replace) Simplest to install Most efficient (because there are losses associated with

charging batteries) You can start small and add (with some limitations)

Cons:

No power when the grid is down. Access to the utility power grid is required.

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System Components

Solar PanelsThese are “Photovoltaic” solar panels which are made up of photovoltaic cells. These cells absorb sunlight and convert it into electric current.

Charge ControllerThese regulators control the voltage going into the battery and protect battery discharge during night time, and it helps allow more electric current flow when the charge is low. In case of over charge, the controller terminates the current.

BatteriesBatteries are an essential part as they store the energy that was converted from sunlight into electricity. You will always need batteries unless you are connecting your panels to the electric grid. These batteries can be wired together to provide the needed storage.

Power InverterThe power inverter converts direct current power from the batteries to alternating power. There are two types; modified or pure sine wave inverters.

DC Disconnect Only needed for a grid-tied system. It is used to turn off the power connection to solar panels.

PART 1 - INSTALLING YOUR GRID-TIED SOLAR SYSTEM

A/B. The Mount Design & Wiring the Trench

In order to move onto the installation of the equipment, you should:

Build the mount Build the frames Adjust dimension for PV system Set up underground wiring Install aluminum rails

After the completion of these steps, before moving onto installation, your design should look similar to that of Figure2.

C. Installation of System Components

1. Before beginning installation, have the equipment ready:

PV panels Micro Inverters Grounding Straps (to ensure continuous

ground of rail splices)

2. Figure out the sequence of bolts and slide the bolt heads into the rail.

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The Mount Design ✓

Wiring the Trench ✓

Installation of system

Components

Wiring the System

Figure 2. Rails are mounted, and the design is ready for the panel installation.

Figure3. Top rail. Bolts are slid into place.

3. Sort out the hardware to connect micro-inverters to the rail.

4. Mount the micro inverters starting from the top rail:

Mark the center of each of the PV panels AC output connector should be towards the

junction box

5. Work your way down the rail, insert the inverters same way.

6. Install a ground strap across rail splices.

7. Clamp temporary wood support to the frame along the line of the bottom of the PV panels.

8.Once aligned, tighten the nut to hold the panel in position.

9. Once all the panels are installed do the final trim of the rails to the length.

D. Wiring the System

1. Before proceeding, please refer to the safety warning.

2. Wiring connections for the micro inverter system(Refer to figure6).

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PV array Disconnect Switch

Disconnect Switch

Circuit Breaker(leave off once

hooked up)

PV panels

micro-inverters(connect to each

other & array junction box)

Figure4. The inverter installed

Figure5. All the panels are put into place.

SAFETY WARNING

The voltages are extremely high and potentially lethal!

Even when the grid is off, system can still present a serious shock hazard!

If you don’t think you can learn how to do this step properly, please hire an electrician!

3. All of these components should be grounded:

The PV panel frames The PV panel support

rails (including ground bonding across splices in the rail)

The micro-inverter case grounds

The PV array junction box (if metal)

The Disconnect switch housing (if metal)

4. Wire the PV array junction box, which is used to connect the first micro inverter to the wiring that goes to the house.

5. Obtain a disconnect switch (local electrical suppliers will have them). And wire the connections.

6. Install the new PV feed in circuit breaker.

7. Wire the PV panels and inverters:

Plug the DC leads from the PV panel into the two DC input leads from the micro-inverter. Keep doing this for all inverters For the last one, plug male cord from last inverter to the female cord

8. At this stage, once you flip the PV circuit breaker and turn on the PV disconnect switch, you should be able to read the date from the EMU unit.

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Figure6.Diagram of the micro-inverter system

Figure7. Wiring of junction box.

Figure8. Meter, house power distribution panel, and the new PV array disconnect switch.

Figure9. Last inverter in line. The cap is screwed in over its input connector.

PART 2 – INSTALLING YOUR STAND-ALONE SYSTEMStep 1: Planning and Preparation

Make sure to do ample research on the specificationsof the system that you’re trying to install. Things of concern may include:

o How much power do you consume?o How will your location affect this system?o How much electricity can be generated?o How much will this cost?o How long before you see any savings?

Don’t forget to add in the costs for a backup charging system just in case the batteries are drained. Have a backup generator ready.

*For this example, the homeowners consume about 24kW hours annually and they receive about 4kWh/m2/day, according to their geographic location specifications. The solar panels they will be utilizing use about 20% of the sunlight’s energy to produce electricity. They wish to become energy dependent.

Step 2: Purchasing the Necessary Equipment

Solar Panelso Manufacturer: Sun Powero ID: SPR-X21-255o Rating: 255o PTC Rating: 241.70o Density: 19.00o Efficiency: 21.57o Tier: 1o Dimensions: 61” x 41”

Batterieso Type: FLA Batterieso Volts: 12 Vo Amp Hours: 357 Aho Temp: 60 Fo Discharge: 0.9o Autonomy: 2 dayso System: 48 V

Charge Controllerso Battery Bank: 12 Vo Max Output: 60 A @ 12 V

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We will be installing a 2.5 kW solar power system using 10 panels. The going price is $4.00/W for a total price of $10,000.00. The total dimensions will come to around 12.4 square meters.

For this system, with these specifications, we will need a total of 12 batteries wired 4 in series, 3 in parallel. Each battery costs about $1,000.00 so the total will be approximately $12,000.00 for batteries.

Seeing that we have 2.5 kW of solar panel power and our controllers can handle about 720 W. We will need 4 charge controllers each costing $610 for a total of about $2,440.00 to ensure safe battery bank charging.

o Max Input: 250 V Inverters

o Type: Magnum Energyo Watts: 2800 Wo Input: 12 VDCo Output: 120 VACo Form: Pure Sine Wave

Othero Circuit breakerso Tools & Wires

Step 3: Hooking It All Up

For this system, the solar panels will be mounted on a rack and connected in series, facing the sun.

We will be using this circuit diagram as a guide to connect our system. The red wires (or white) are positive, the black wire are negative. (See Figure10.)

The connection between the inverter and plug point includes: A live (RED) wire, a neutral (BLACK) wire and the grounding (GREEN) wire.

Be careful when making these connections and make sure the power is turned off!

Do not cross wires and make sure to cut all wires to an appropriate length and strip the ends with a wire stripper.

1. Solar Panel Connections Connect the wires to the solar panel. Let the

red wire be connected to the positive terminal and the black wire to the negative terminal.

Connect the other end of the red wire to theinput of the first circuit breaker. Then, connect the other end of the black wire to the input of the second circuit breaker.

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This inverter has an input that matches that of the battery bank and delivers an output that is accepted by most loads of this household. One inverter of this type should meet the house’s instantaneous power and surge requirements. One of these costs about $2,000.00 to buy.

Figure10. Circuit Diagram

2. Circuit Breaker Connections Connect the output of the first circuit

breaker to another red wire and the output of the second circuit breakerto another black wire.

Connect these newly connected redand black wires to the positive and negative terminals of the chargecontroller.

Tighten the screws of the terminalsusing a screwdriver.

3. Charge Controller Connections Connect a red wire to the output of

the charge controller’s positiveterminal and connect this to the inputof the next charge controller. (ParallelConnection)

Then connect a black wire to theoutput of the charge controller’s negative terminal and connect this tothe negative input terminal of the next charge controller. (ParallelConnection)

Make these connections until all charge controllers are hooked up. Then connect the final output of the charge controller bank’s positive and negative terminals to the positive and negative terminals of the battery bank.

4. Battery Connections To connect in series, connect red to black and black to red. To connect in parallel, connect

red to red and black to black. If you aren’t sure how this is done, hire an electrician.5. Inverter Connections

From the battery bank, connect the red wire from the ending positive terminal to the positive input terminal of the inverter. Connect the black wire from the negative terminal of the battery to the negative input terminal of the inverter.

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Figure11. Solar Panel Junction Box

Figure12. Circuit Breaker Connection (Below)

Figure13. Parallel Charge Controllers (Below)

6. Power Meter Connections The output of the inverter has three terminals: Live, Neutral and Ground. Connect the

power consumption meter to the three terminals of the inverter’s output. Finally, plug the output of the power meter to the plug point connections.

Step 4: Testing the System

If you have a smart meter, you will know that the system is working because it will show you the watts that are being generated. You can always plug in a lightbulb to see if it is working also.

If the lightbulb or smart meter indicates that the system is not working, go back and make sure that all your wires are straight and redo the calculations to ensure that you haven’t overloaded any circuits.

References http://www.homepower.com/articles/solar-electricity/design-installation/designing-stand-

alone-pv-system/page/0/5?v=print http://www.iflscience.com/environment/here-s-roundmap-get-us-run-100-renewable-energy-

2050 http://www.instructables.com/id/Apartment-Solar-System/?ALLSTEPS http://www.instructables.com/id/Solar-Power-System/?ALLSTEPS http://www.solardesigntool.com/components/module-panel-solar/Sunpower/2228/SPR-X21-

255/specification-data-sheet.html http://solarsimplified.org/connecting-to-the-grid/ongrid-offgrid http://www.wholesalesolar.com/charge-controllers http://www.wholesalesolar.com/deep-cycle-solar-batteries http://www.wholesalesolar.com/power-inverters https://www.youtube.com/watch?v=GnZFi9CzF9Q

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Figure14. Battery to Inverter Connection

Figure15. Smart Power Meter