https://solar.lowtechmagazine.com/power.html

 

LOW-TECH MAGAZINE

This is a solar-powered website, which means it sometimes goes
offline
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Power

This website runs on a solar powered server located in Barcelona, and
will go off-line during longer periods of bad weather. This page
shows live data relating to power supply, power demand, and
energy storage.

Power supply

This is a forecast for the coming days, updated daily:

This weather forecast is powered by DarkSky.

Power demand

These are live power statistics of the solar powered server:

(* load average per 15 minutes)

Battery meter

The background of this website is a battery meter, designed to always
display the relationship of the energy powering the website and the
visitor traffic consuming it.

The battery meter simply represents the voltage of our battery. For
example, a storage capacity of 68% equals 12.68V, and a storage
capacity of 8% equals 12.08V. The voltage reading is the "naked" data
on which each battery meter relies to display a percentage. It
doesn't always correlate with the energy storage capacity, because
it's also influenced by the electric load (which lowers the voltage)
and the solar insolation (which increases the voltage).

Because our load (the server) has a rather constant power use, during
the day our battery meter reflects the local solar conditions. If the
panel receives full sun, the voltage will raise above 13V, coloring
the whole website in yellow. However, if it gets cloudy, the battery
meter will decrease and the blue background is revealed. During the
night, the battery meter reflects the storage capacity of the
battery accurately.

When the voltage of the battery drops below 12V, and the whole page
is coloured in blue, the solar charge controller shuts down the
system and the website goes offline. It will come back when the panel
receives full sun again.

Showing a "correct" representation of the storage capacity requires
calibration and algorithms in relation to a specific battery. This is
troublesome, because we keep experimenting with different sizes of
batteries and solar panels to find the optimal balance between uptime
and sustainability. Furthermore, the naked data are more informative
for people who understand how a solar PV system works. For example,
the battery meter also reveals the state and age of the battery.

Since 12 January 2020, the website runs on a 30W solar panel and a
(new) 168 Wh lead-acid battery. From September 2018 to January 2020,
the website was powered by a 50W solar panel and an (old) 86
Wh battery.

image

The accessibility of this website depends on the weather in
Barcelona, Spain.

LOW-TECH MAGAZINE

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    (c) Kris De Decker
    solar [at] lowtechmagazine [dot] com

       

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