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This is a badge bit (BB) that is part of the PEP curriculum.  Completing this BB is part of getting the sand badge in Electricity.

In this Badge Bit, you will install a DC solar system.

Solar systems can be huge (insert Milky Way joke here).  But they don't have to be.  Let's harness the power of the sun to build a small DC solar system with battery storage.

Here are a few videos:



To complete this BB, the minimum requirements are:
         o choose one of the following systems to build:
              - small solar music cart and phone charging station
                     o includes 12v bluetooth speakers hard wired
              - small DC system on a shed:  lights and phone charging
              - tiny home power system: lights, phone charging, outlets
              - RV or camping power system: lights and phone charging
         o must have at least one 12v outlet
         o must have at least one 5v phone charging outlet
         o must include a charge controller
         o must include a battery
              - must be able to put out 100 watts for 6 hours.

Provide photos or video (< 2 minutes) of the following:
   - Description of the system, power and capacity.  Explain how the battery(s) will put out 100W for 6 hours
   - Area where the system will be installed
   - Parts before you install/assemble them
   - Completed installation
   - Evidence of a phone charging

Side Notes:
If you have an alternative solar installation that you'd like to do of a similar complexity, post below and ask if it could be added as an option.
COMMENTS:
 
Erik Pehoviack
Posts: 32
Location: Hemingford Nebraska
19
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Hello Permies community. This is my second installment towards the PEP sand badge for electricity. In this presentation I will cover completion of a small solar trailer with battery storage I developed for our meager light usage and device charging. This project was finished back during the infant stages PEP but I want to pass the knowledge on.
This little trailer will be the base for the solar panels and charge controllers.



This location in the basement will house the balance of components.



I used the following components for the photovoltaic and energy storage solution:
3 - 110 watt Mitsubishi photovoltaic modules


3 - Morningstar Sunsaver 6 charge controllers




1 - 60 amp circuit breaker (E), 2 - Group 27DC batteries (A), 1 - Blue Sea Systems battery meter with cigarette lighter port and USB outlets (C), 50’ of 4 conductor 8 gauge trailer wire (D), 2 - 000 gauge battery cables (F), and an old automotive fuse panel (B).
When sunlight strikes the panels electricity is sent to the charge controllers where it is optimized and is then sent through the 8 gauge cables, through the circuit breaker, to the batteries. The charge controllers limit power production in relation to capacity and temperature. The power then travels from the batteries, which are wired in parallel, to the fuse box where it is distributed to the power center circuit.
According to turbinegenerator.org my location in Hemingford Nebraska should produce 5.2 sun hours per day fixed, 6.5 sun hours per day single axis, and 6.7 sun hours dual axis. If I leave the trailer facing due south it should be able to produce 1.7 Kwh per day (330 watts of power x 5.2 hours of operation).

The charge controllers are mounted behind the solar panels under an aluminum enclosure.


Electricity as measured on the PV side of the three module connection is 14.6 volts. My DMM isn’t big enough to risk measuring total current output.



Here are the panels situated outside of our RV from which the batteries came. They receive power from 8 am to 4 pm during the winter months and from about 7 am to 8 pm summer months. We have much shading to the east and west but can turn the trailer to optimize production.




The batteries were relocated to the basement to control their climate, extending life. This also provided a weather tight location to put the fuses and power output ports. Here is a photo of the power panel connected to the ports and built in voltmeter to continuously monitor battery health.




Here is where the devices get charged. It is a spot on the floor next to our south living room window. The USB cords come up through a hole in the floor (orange arrow) and are held from falling through with a clothespin. As you can see in the pink circles the phone is charging and has achieved 100% charge.




Here is a photo of the finished storage / usage portion of the system.


Finally, an explanation of power production: In order to meet specifications this system must produce at least 100 watts for 6 hours. I’m not sure if that is solar wattage or battery wattage, but I’ll demonstrate both.

As mentioned before our latitude of 42 degrees will produce 6.5 sun hours if I move the trailer along with the sun. 6.5 hours x 330 watts (total for all three panels) produces a total of 2,145 watts. Divided by 6 (hours) that equals 357 watts per hour.

On the battery side the two group 27DC batteries are wired in parallel, doubling their Amp-hour capacity to approximately 200 Amp-hours. Deep cycle batteries are rated for AH’s using a specified amp draw for a specified time, in this case 5 amps for 20 hours per battery. Doubling this capacity with two batteries effectively provides 8.3 amps (100 watts) for six hours. In addition to possible BB credit I'd like to offer this tutorial for those interested in renewable energy. Many components can be picked up cheap if one watches for deals. Thank you for reading.
Staff note (Mike Haasl) :

I hereby certify this BB done exceptionally well. Great job Erik!

 
paul wheaton
master steward
Posts: 31963
Location: missoula, montana (zone 4)
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Ben Peterson has offered his full ebook of plans for portable solar stations to be free for a while.



Get is here.

Thanks Ben!


 
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