AEF photovoltaic system: Difference between revisions

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Background and Descrition of Opportunity

Bob and Cody have modified the off-grid photovoltaic system out at the Arcata Educational Farm. The system previously in place consisted of most components; solar panel, battery, charge controller, wiring, and answering machine. The new system powers a new answering machine as well as a compost toilet fan. This system provides the means for shareholders to contact the AEF for the food season. Previously, there was no power to the answering machine and messages could not be left by veteran shareholders or interested shareholders. We assessed the photovoltaic system; replaced any broken parts (eg. old wiring, bad battery, etc.) and added any components (eg. inverter) that may improve the operation of the system. Through the process of modifying the photovoltaic system, we put a "how to" manual together for current and future directors at the Arcata Educational Farm.

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  Fig 1:Existing system components

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  Fig 2:Existing solar panels on building at the AEF

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  Fig 3. Old answering machine

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  Fig 4. Old outlet for answering machine

Proposed Timeline

Criteria

Literature Review

'There has been substantial discussion and writing on PV design, installation and maintenance. This system is not-grid connected so we focused on the same literature review done for our other project: Engr_305_solar_learning station and is here literature review and Photovoltaics.

Components and their functions

1-Panel

Collection of PV cells designed and installed on the panel depending on serial or parallel configuration

2-Absorbed Glass Mat (AGM) Sealed Battery

Storage of DC Electrical Current.

3-Charge Controller/Low Voltage Disconnect (LVD)

Regulates battery voltage and controls the charging rate, or the state of charge, for batteries. LVD shuts system off when voltage drops below 11.6 v and turns it back on after the battery has charged to 12.6 v.

4-Inverter

Changes direct current (DC)generated by the Panel to alternating current (AC)used by households.

Load (Answering Machine)

Any electrical component within a circuit that draws power from that circuit.

Most loads can be turned on and off, such as a light bulb or a refrigerator.

Loads are either AC or DC.

Fuses

When a current exceeds a fuse´s rated amperage, the circuit opens and stops all current flow. When a fuse has "blown", it must be replaced.

Meter

A gauge that allows you to see from where you are pulling your power, and how much power is being drawn from the loads.

5-Outlet

Outlet to run AC appliances-answering machine

Operating/Maintenance Instructions for components

Answering Machine

The answering machine is a used ATT 1715 and the user's manual is on-line

Charge Controller/Low Voltage Disconnect

The charge controller is a SunSaver 10 Amp Unit and the user's manual is on-line

Inverter

The Inverter is a Xantrex XPower Inverter 400 and the user's manual is on-line

System Installation

After assessing what components could be re-used from the old system and answering machine(Fig 1, 2, 3, 4)), we got together to plan out the re-installation. Cody, being better at tough installation tasks, rebuilt the battery box(Fig 5), re-wired and attached the charge controller and inverter( Fig 7,8,and 9), and coached Bob as he re-wired the AC portion of the system. Bob ran Romex wiring from the inverter to the AC plug box. He also wired the AC outlet as it previously had direct DC wiring(Fig 4). Bob re-wired the compost fan to protect anyone from getting shocked if they fell asleep while on the toilet(Fig 13). We replaced all old wiring with new wiring and fastened with the existing hangers.

We were careful to have all components either covered from the elements or away from incidental human contact. This part was actually easier than the learning station as we could work at the same time instead of one at a time because of space. Once we were done and plugged in the new answering machine, it all worked perfectly and it looked good(Fig 10, 11, and 12)! For awhile.....

System Installation Photos

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  Fig 5. New battery box

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  Fig 6. Bob installing new AC outlet for answering machine

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  Fig 7. Cody wiring the charge controller

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  Fig 8. Wiring the new system. Team work!

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  Fig 9. Hooking up the final wire to charge controller

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  Fig 10. Sarah and Bob fine tuning the answering machine

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  Fig 11. New answering machine and AC outlet

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  Fig 12. New system

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  Fig 13. New wires for composting toilet fan

System Testing

First we assessed the current system and figured out which components were still good and which ones were bad. The battery was five years old, would not hold a charge, and needed to be replaced. The charge controller still worked, but we decided to replace the old one with a new charge controller with a low voltage disconnect (LVD). This prevents the battery from being discharged to levels that decrease its life.

Using the old wiring coming from the solar panel, we tested the voltage coming from the panel to the charge controller. Only 1.79v were coming through so our initial thought was a bad panel. CCAT had some panels and were willing to donate one in case the original was bad. On a sunny day the panels in their Solar Trailer were all tested and one very similar to the existing panel was donated. But, it turned out that it was the old wiring. After removing the old wiring and testing the panel, it showed us 19.5v. The lifespan of a panel at full voltage is 15 - 25 years and after that the voltage output only slightly decreases.

After the system was completely installed, we tested the answering machine and everything worked. We were able to leave messages on the answering machine for a week before the system turned off. It now has been a full week and the system has not yet turned on, we tested our system at every point checking to make sure that our wiring was done correctly. The wiring was determined good and now we are testing individual components. The inverter worked when hooked up to battery, so now we're testing the battery to make sure it will hold a charge. All components are new so it is difficult to troubleshoot a new product being bad. After charging the battery up with a battery charger a load test was performed to make sure the voltage didn't drop rapidly. The battery was determined good, so now its down to the charge controller and/or the panel. With the battery charged we hooked it back up to the system and it worked again for a week. By bringing another battery in and hooking it up directly to the panel(around the charge controller), we were able to determine that the panel and wiring are good and eliminate them from scrutiny. We are investigating the charge controller. At this point its a matter of patience, time, and more trouble shooting if the problem persists.

List of steps to take when testing this system:

1. Test system meters-Test on a device where you know the voltage and verify it is working and correct
2. Array/panel voltage-Use a DC voltmeter/ampmeter to measure the voltage/amperage(in full sun) in an array/panel and record
3. Battery voltage-carefully measure the voltage of the battery before and after connecting and record
4. Check status indicators on charge controller and inverter if available
5. Check all wiring to see if any is live by testing voltage and/or current at all points before and after a component
6. Check all terminals and wires for loose, broken, corroded or burnt connections or components
7. Make sure charge controller is clean
8. Fire up the system under full sun and re-test each point and component for common voltage/amperage
9. Turn on the answering machine!

Reference: Maintenance and operation of stand-alone Photovoltaic systems (1991). Sandia National Laboratories, Albuquerque, New Mexico 87185-5800 157

Answering machine has no power:

• Check in another outlet to make sure it is not broken and/or try another power cord
• Use voltage meter to check voltage by carefully touching both ends individually to a separate end of a circuit. Test outlet, panel, charge controller, battery(carefully!) to see if the voltage is at or near 12 volts
• If any of the components have less than 12 volts, give the folks at CCAT a call.

Precautions

• Do not touch any of the wires with your hands or a metal tool when the system is connected.

Read any material in our "how-to" packet before attempting to fix.

• Only let someone that knows what they are doing repair or change the system or its wiring.

Budget