Wordberry Sun Pie

Solar powered Raspberry Pi WordPress server.

The Internet and Environmental Impact

The Internet uses more than 416 Terrawatt Hours of electricity per year.

That is more energy than the entire United Kingdom.

Tom Greenwood – Kinsta.com

You can look up the estimate of carbon emissions for a website at https://www.websitecarbon.com/

If we can get zero emissions web hosting we can get our service listed at places like The Green Web Foundation.

Raspberry Pi 3 B

Input Power
5V 2.5A DC
via microUSB connector or GPIO header
Power over Ethternet (PoE) 802.3af with add-on

Consumption
700mA – 1A depending on peripherals
300mA per Voltaic

CPU
Broadcom BCM2837B0, Cortex-A53 64-bit SoC @ 1.4 GHz
1GB LPDDR2 SDRAM

Raspberry Pi 3 A+

Input Power
5 V/2.5 A DC via micro USB connector
5 V DC via GPIO header

Consumption
500mA on average
200mA per Voltaic

CPU
Broadcom BCM2837B0, Cortex-A53 (ARMv8) 64-bit SoC @ 1.4GH
512MB LPDDR2 SDRA

Pi3 3 A+
On Amazon from LuluPepper Media ($35)
From CanaKit ($25)

SD Card 32GB
From CanaKit w/ NOOB ($20)

Case
From CanaKit ($5)

Solar Pack

There are multiple travel solar panel packs with batteries for charging phones etc.

A 24000mAh from Hilucky at Amazon ($43) should provide 24h at 1000 mA for our device.

Electrical Energy Basics

W = V * A
Power measured in Watts (W) = Voltage measured in volts (V) x Current measured in amps (A). In electrical engineering this is P = VI because “I” is french for “intensity of current”.

Solar Efficiency: 40%
A solar panel in our setup (low efficiency) will yield around 40% power loss.
A 10W panel will generate 6W.
Full sun for 6h/day would yield 36Wh.

Our Power Environment

B+
Average (per Voltaic Systems): 300mA @ 5V = 1.5W x 24h = 36Wh / day

A+
Average: 200mA @ 5V = 1W x 24h = 24Wh / day

Battery System

Voltaic V44 USB Battery Pack ($69) : 12,000 mAh |44 Wh | 5V / 2A — Input 5-6V 2A

V88 ($129) : Output 24,000 mAh | 88 Wh |5V / 2A — Input 15-25V 3A

Solar Panels
Voltaic 9W Solar Panel ($79) : Peak 6.5v | 1,420 mA | 9.2

Voltaic 17W 18V ($129) : Peak 18.9v | 930 mA | 17.6W

Power Control Board

Solar DC input with battery switching.

Sleepy Pi 2 ($60)
Solar Pi Platter ($60)
Witty Pi 2 ($22

Thermal Considerations

CPU

The CPU will throttle when the core temp reaches 80c (about 175 f).
The CPU will shut down at 85c (about 185 f).

There are heat sinks available for the processors.

We may want to consider a case that is also a heat sync. Though a metal (aluminum?) would block WiFi.

Other option is passive cooling via vertical mounting and convection.

Maybe drain excess power when the battery is full by running a fan rather than “throwing away” excess solar at that point.

Other People’s Notes

Solar Power for Raspberry Pi from Voltaic – Mar 10 2017

Raspberry Pi LAMP Server on Raspberry Pi Docs
Installing WP on Raspberry Pi by Raspberry Pi StarterKits – Feb 24 2018

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