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Small DC only solar system - PEP BB electricity.sand.solar

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Raphaël Blais

pollinator

Posts: 273

Location: Gaspesie, Quebec, Canada, zone3a at the bottom of a valley

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posted 2 years ago

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Edge case submission

Note1: oops, did'nt see it was only the battery energy for the 100watt for 6 hours. Will connect one of my house trojan agm battery, 102ah@10hr, and get a new picture as soon as i can.

My submission for bb small dc system.

Took a car battery and a reused system that i had stored. I didn't have the info on the ah of the battery, but searching on the net, i found the calculation about the reserve capacity (RC) tagged on the battery on the calculation to use it.

source: Calculator academy web site

AH = BR *60 *25 / 3,600
Where Ah is the amp hours
BR is the battery reserve capacity (minutes)

My BR is 90 minutes, so
90*60*25 / 3,600 = 37,5ah usable energy

37,5ah * 12v = 450w, missing 150w

The panel is rated for 2,2a and 17v
2,2a *17v *6h = 224,4w

So with a full battery and a bright sun and perfect angled solar panel, i can achived 100w for 6hours.
450w+224w= 674w

For a regular 100w consuption of energy, i would install a bigger panel or battery.

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Radis.
Living and growing on my small homestead near a project of permaculture school.

"There are no non-radical options left before us" Naomie Klein in This Changes Everything

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Staff note (gir bot) :

James Alun approved this submission.
Note: You've achieved the technical ability for the construction of the system. In the future, I would like to see the wiring tidied up please. And a quick point aboit your calculation, multiplying by 60 and then divig by 3600 converted minutes to seconds to hours, (90*25)/60 would have been sufficient.

Staff note :

Discussion is ongoing behind the scenes about this BB submission... Unapproving it for the moment...

Staff note (gir bot) :

Someone flagged this submission as an edge case BB.
BBV price: 0
Note: Sorry. A 100 watt bulb requires 8.333 amps at 12 volts. 8.333 x 6 hours = almost exactly 50 amp hours. It appears your battery is a little too small to meet this posted requirement "Explain how the battery(s) will put out 100W for 6 hours." Using an inverter would introduce losses that would increase the overall power needs even more.

Bethany Paschall

pollinator

Posts: 196

Location: In the foothills of the Blue Ridge Mountains

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posted 1 year ago

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Submission flagged incomplete

Our photovoltaic panel is a 100 watt 12 volt rigid type. The battery is a 27DC 109 amp hour 12volt battery. Using the formula
amps x volts = watts we have 109 x 12 = 1308. Which will gladly give 100W for 6 hours without drainging the battery to an unhealthy level. The solar panel will keep our battery topped off with juice.
Now our storage shed has working lights and a charging station!

The phone charger, 12 volt DC outlet, and lights are wired to the fuse box that I connected as my lode on the controller. Here are the links to the installed lights and outlet:
https://permies.com/wiki/112699/pep-electricity/Install-permanent-DC-light-fixture#1811989
https://permies.com/wiki/110313/pep-electricity/Install-volt-DC-Outlet-electricity#1845944

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Sunny spot to eventualy install the panel (It will be put up there but for the sake of convenience, it is on the ground in the pictures)

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Solar controller hooked up to shed fuse box

"And we urge you, brothers and sisters, warn those who are idle and disruptive, encourage the disheartened, help the weak, be patient with everyone. Make sure that nobody pays back wrong for wrong, but always strive to do what is good for each other and for everyone else."
1 Thessalonians 5:14-15

Staff note (gir bot) :

Someone flagged this submission as not complete.
BBV price: 1
Note: Please include a picture of the 12 volt outlet. It appears that the phone is charging from a different USB outlet than the one built into the controller. The panel needs to be fully installed for this BB so include a picture if it mounted on the platform.

Staff note (gir bot) :

Mike Barkley approved this submission.
Note: Allowing a little leeway due to the long delay. The required pix are shown in the links.

Staff note (gir bot) :

Jeff Bosch flagged this submission as not complete.
BBV price: 1
Note: You can't not use the same work for two BBs in the same Badge. You got the points for installing the DC outlet, the requirement for the DC outlet in this badge needs to be another outlet.

Bethany Paschall

pollinator

Posts: 196

Location: In the foothills of the Blue Ridge Mountains

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posted 1 year ago

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I have updated my post to include more photos and information about my outlet and lights.

Opalyn Rose

gardener

Posts: 1557

Location: Washington State

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posted 1 year ago

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Approved submission

Here is my submission for the Electricity - Sand (for Straw Points) - Setup a DC only solar system.

Information on the system and meeting the minimum requirements:
- This is an RV or camping power system
- must have at least one 12v outlet - it has 8 outlets
- must have at least one 5v USB outlet - yes
- must include a charge controller - yes plus a battery management system with wifi and phone app
- must include a battery - the system has four batteries tied together in series. they are 3.2 v LIFePO4 with a 280 Ah capacity, Voltage of 3.29 V, and 0.21 m Ω IR.
- MATH: 280 Ah * 3.29V = 920 Wh - this means that the system can put out 100W for 9 hours
- Area where the system will be installed - this is an RV system so the components and batteries are stored in a Rubbermaid box and the solar panel is stored in its own protective easy-carry case. The system was set up on a campsite at the lab. The solar panel leans on the storage/battery box providing shade to the batteries and a good solar aspect for the panel.

Provide photos or video (< 2 minutes) of the following:
- Parts before you install/assemble them
- Completed installation
- Evidence of a phone charging

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