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Description

Tutorial to setup a nextcloud server (equivalent to google drive but free and adapted to collective organisations) on a single board computer (photovoltaics powered)
 
This tutorial is not really "lowtech" at first look because we talk about computers and photovoltaics
 
However it is as didactic as possible and follows a lowtech philosophy to share knowledge, avoid unreachable tech by information rentention, complexification by design, or proprietary
dependance by design.
 
We also give sizign tools for photovoltaics with a few explanation.
It's up to to you to size your computer working hours on a sun schedule, ie respecting human temporalities.
 
Nextcloud (framasoft offers a service here: https://www.frama.space/abc/fr ) is a cool service to organise collectively and allows to share files, have a directory, a chat, work cooperatively on libreoffice files, and even do visios. We can also imagine mobile infokisosks on this principle.
 
The tutorial puts into question the vpn market, the phtovoltaics with brand new and expensive batteries (in reality photovoltaics has become too competitive compared to petrleum and even more compared to nuclear power!), and the gafam market and their surveillance design is damaging trust and social links.
The commands are those for a debian system
 Finally, the tutorial is made iwth 4G modem (and a wired connection to orange pi which has no wifi card by default), and is updated on this 10th of april for a raspberry pi connected
to a "shared wifi" of your telephone (see stage 6 for a wifi in wpa3 and stage 16 for a wifi in wpa2)

Steps

The links to the photovoltaics material are in the autonomie.ods file (readable with libreoffice) attached to this tutorial.

- raspberry pi :

42€ on leboncoin

-Orange pi :

single board computer: Orange pi 5

single board computer with 4,8,16 or 32 Go of ram

2,4Ghz ARM Cortex-A55 CPU

This card is compatible with nvme pcie 2.0 hard drives (2242 or 2230, pcie is retrocompatible ie 3.0, 4.0 and 5.0 work with lower speed on orange pi 5)

Same principle as here but a bit more powerful and we can plug a hard drive (useful for nextcloud which is made to host files) and it starts automatically on a usb stick

Price: 143€ brand new on aliexpress in version 16 Go on the 2nd of august 2023

Second hand on leboncoin: we find more easily raspberry pi at around 100€.

It is necessary to buy a small box at 10€ (or make one) to avoid a naked single board computer

-hard drive

Here we use a kingston usb stick of 32Go and a nvme samsung 512Go card

We can plug a hard drive of higher capacity in usb, or a nvme card (nvme pcie 2.0 ssd 2242 or 2230) compatible with pcie 3.0 4.0 and above but the speed is reduced

A nvme samsung 2242 card of 500Go is about 50€ on the 2nd of august 2023.

-usb stick : 10€

- rj45 cable: 5€

-Internet box or 4G modem according to your internet connection

-solar pannel: here we use a flexible 120W pannel bougth 115€ brand new but we can find second hand ones at 30€ on leboncoin for an equivalente peak power.

Note: for the theoretical need. See file autonomy.ods

-second hand battery: use the previous lead acid battery of your car when it crashes when it's too hot in summer!

-12V/24V-usb 5V battery converter: 20€ avoid amazon if you can

- pwm regulator 30A: 30€ brand new if you dont buy corporate brand

- DRL (day/night switch 13V): 1,5€ brand new

(key word "Kit de feux de jour à LED pour voiture, contrôleur marche/arrêt automatique DRL" in french)

-electric mc4 cable: 20€

Total second hand price for orangepi: 256,50€

Total brand new price for orangepi: 431,50€

Total second hand price for raspberry: 165€

See autonomie.ods

-

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1. Download dietpi and prepare your usb stick

For installation, i recommend using diepti. It is interesting in particular for it is lightweight for single board computers, but also because the automatic installation of free software

with a relatively "user friendly" menu. We can mention among all the installable software at boot (https://dietpi.com/dietpi-software.html)

domotic apps, interesting to save energy based on weather, but also tor relay to contribute to the relatively anonymous tor network, interesting for any "eco-terrorist" we are.

We must also mention "younohost"(https://yunohost.org/fr) which is french and who does the same job as dietpi for raspberry and which is also "user friendly" or even more. I have not yet tested yunohost because i had put aside raspberry pi after too many weird mouse bugs. My research to avoid these weird mouse bugs have not concluded positively to any solution (purism, odroid, raspberry, orangpi, macbook, windows, see security section), i can only send a feedback on what i have really tried.

https://dietpi.com/#download

( for younohost : https://yunohost.org/fr/install/hardware:arm)

Select the single board computer (orange pi in the present case) and then download

Unzip the obtained archive

Use balena etcher to create a bootable usb stick to install dietpi on your single board computer (orange pi 5 in the present case but it works the same on other single board computers)

https://etcher.balena.io/#download-etcher

Double click on the downloaded file

Select the dietpi downloaded image, select your usb stick, click on flash.

You only need to plug the usb stick on the orangepi and it will boot automatically on the usb stick.

For a raspberry pi, we use a sd card but we can configure the usb boot as well (see here:https://makerhelp.fr/booter-un-raspberry-pi-4-sur-un-disque-dur-ou-un-ssd-en-usb )

Install nextcloud

Power your orangepi/raspberrypi with the usb stick plugged.

The default login at boot is root and the password is dietpi.

Follow the menus at first boot to install the nextcloud service. It is very easy, it is in english and everything is automated. I have put the images of the menus you have to select. to install nextcloud: see in this stage and on stages 3 to 6

You can move the menus with the keyboard and the arrows and the tab key

Select with space and validate with enter

See images at stages 3 to 6 for the installation process and select the entries

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If you don't have a box and you have a orange pi or raspberry pi and you want connext to a wifi (for example wifi of a shared connection smartphone)

Dietpi gives a utility to configure automatically the wifi which works on raspberry. At my place it works only if the network is wpa2. If you want to activate wpa3 or if
you want to configure your wifi manually, here are the steps to follow.

<div class="mw-translate-fuzzy">
Linux is a bit complicated for network management. A lot of programs exist allowing to manage networks (networking, network interfaces, ifup, wpa_supplicant, network_manager, ifconfig, ip...)
network_manager, ifconfig, ip...).
</div>

If you know well, do what you think is best suited for you.

Otherwise, we will use the default programs installed with dietpi for managing wifi interfaces: wpa_supplicant and dhclient.

Begin with plugging a wifi usb adapter to your orangepi or verify your wifi adapter on your raspberry pi is well detected.

On a orangepi: verify the adapter is well detected entering: <pre>lsusb</pre>

This command will list the usb devices and you should see your wifi usb stick in the list. Then verify that the drivers of your usb stick have been loaded entering: <pre>dmesg</pre>

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<nowiki>[Watch out, this section puts into question the vpn market!!]</nowiki>

This section is useful for 4G connections or in wifi on a smartphone (4G or 5G)

The 4g has the advantage to be mobile with a very low power consumption of the modem, around 5W, and you can find 4g modems without wifi to limit the attack surface of your server (example netgear lm1200 around 150€)

what is a vpn?

The vpn are mainly known to be vpn "clients". Ie you use it on your computer to become "anonymous".

The vpn is in fact a tunnel between your computer and another distant computer, from which your requests go on to the internet. Your traffic in direction of the internet goes through this tunnel.

Internet then thinks your requests come from this distant computer. That is to say your public ip becomes distant computer one.

Your internet provided doesnt see the traffic between your computer and this distant computer, which makes you "anonymous"

In reality, you are anonymous for your internet provider, but you only move the trust you had in your internet provider to your vpn provider who can see your traffic.

The vpn has also other uses like giving you access to websites being filtered on a geographic basis (information that can be deducted from your public ip)

You can very well create your own vpn server, and in our case, this vpn server will redirect the internet requests made on this server to your orangepi/raspberry pi going through the tunnel (in the other direction than when you use it as a client to access the internet)

An wee will see how.

Create a server on gandi.net

Create an account on gandi.net, then create a server on gandicloud vps. See images for the 3clicks server creation that costs 5€/month.

To create a ssh key and log in see:

<nowiki>https://docs.gandi.net/fr/cloud/operations_courantes/connexion_serveur.html</nowiki>

Once logged onto the server

launch the command to install wireguard and the necessary dependencies

<blockquote>sudo apt update && sudo apt install wireguard resolvconf iptables nano -y</blockquote>

Launch the same command on your orangepi/raspberry pi

then launch the commands on your orangepi/raspberry pi server to create the private and public wireguard keys <blockquote>sudo mkdir -p /etc/wireguard 
sudo sh -c 'wg genkey &#124; (umask 0077 && tee /etc/wireguard/private_key) &#124; wg pubkey > /etc/wireguard/public_key' </blockquote>

Afficher la clé publique sur votre orange pi/raspberry pi en tapant <blockquote>sudo cat /etc/wireguard/public_key</blockquote> Afficher egalement la clé publique sur votre serveur en tapant <blockquote>sudo cat /etc/wireguard/public_key</blockquote>
Display the public key on your orangepi/raspberry pi typing <blockquote>sudo cat /etc/wireguard/public_key</blockquote> Afficher egalement la clé publique sur votre serveur en tapant <blockquote>sudo cat /etc/wireguard/public_key</blockquote>

Then enter the following commands to create a configuration file /etc/wireguard/wg0.conf on your server:

Type the following lines (replace cle_publique_du_orange_pi_ou_raspberry_pi) by the one previously displayed

<blockquote>echo "[Interface]" &#124; sudo tee /etc/wireguard/wg0.conf echo "Address=10.10.0.1/24" &#124; sudo tee -a /etc/wireguard/wg0.conf echo "PrivateKey=$(sudo cat /etc/wireguard/private_key)" &#124; sudo tee -a /etc/wireguard/wg0.conf echo "ListenPort=12345" &#124; sudo tee -a /etc/wireguard/wg0.conf echo "[Peer]" &#124; sudo tee -a /etc/wireguard/wg0.conf echo "PublicKey=cle_publique_du_orange_pi_ou_raspberry_pi" &#124; sudo tee -a /etc/wireguard/wg0.conf echo "AllowedIPs=10.10.0.2/32" &#124; sudo tee -a /etc/wireguard/wg0.conf</blockquote>

Then enter the following command on the server to launch and activate the vpn service <blockquote>sudo systemctl start wg-quick@wg0 sudo systemctl enable wg-quick@wg0</blockquote>

then enter <blockquote>curl ifconfig.me</blockquote> to obtain the public ip of your server

Type the following lines (replace cle_publique_du_serveur by the one previously displayed and ip_publique_du_serveur by the one previously displayed) :

<blockquote>echo "[Interface]" &#124; sudo tee /etc/wireguard/wg0.conf echo "Address=10.10.0.2/24" &#124; sudo tee -a /etc/wireguard/wg0.conf echo "PrivateKey=$(sudo cat /etc/wireguard/private_key)" &#124; sudo tee -a /etc/wireguard/wg0.conf echo "[Peer]" &#124; sudo tee -a /etc/wireguard/wg0.conf echo "PublicKey=cle_publique_du_serveur" &#124; sudo tee -a /etc/wireguard/wg0.conf echo "AllowedIPs=10.10.0.1/32" &#124; sudo tee -a /etc/wireguard/wg0.conf echo "Endpoint=ip_publique_du_serveur:12345" &#124; sudo tee -a /etc/wireguard/wg0.conf</blockquote>

The line AllowedIPS defines the destination ips (outgoing) that will go through the tunnel and will be encrypted but also the ips authorized to enter. If you want to configure your "client" (orange pi or raspberry pi) to use the vpn to access the internet, replace AllowedIPs=10.10.0.1/32 with AllowedIPs=0.0.0.0/0 Defining 0.0.0.0/0 we indicate that all the traffic of the orangepi/raspberry pi will go through the wireguard tunnel and that all the entering ips will be allowed. It is then important to configure well a firewall for the server!

To verify wireguard works, launch the following command on the vpn server: <blockquote>ping 10.10.10.2 -c 4</blockquote> The ping must work

This doesnt work systematically on my computer, but i am sure that if you try, your digitla weather forecast being better than mine, it will work on your computer ;)

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<nowiki>In the case where it would not work with wireguard, you could user openvpn, (which is configurable with the mouse!) </nowiki>

Gandi.net proxy server configuration: For that, follow the stages on https://openvpn.net/vpn-server-resources/installing-openvpn-access-server-on-a-linux-system :

27/11/23 update: there is no bookworm version of openvpn-as available for debian. Think about installing bullseye debian version

<blockquote>apt update && apt -y install ca-certificates wget net-tools gnupg

wget https://as-repository.openvpn.net/as-repo-public.asc -qO /etc/apt/trusted.gpg.d/as-repository.asc

echo "deb [arch=amd64 signed-by=/etc/apt/trusted.gpg.d/as-repository.asc] http://as-repository.openvpn.net/as/debian bullseye main" &#124; sudo tee /etc/apt/sources.list.d/openvpn-as-repo.list

apt update && apt -y install openvpn-as

</blockquote>

If the commands above dont owrk, it is possible openvpn has updated elements. Thanks to see  https://openvpn.net/access-server/, sign up and follow the installation instructions

Then go on the server configuration adress: https://<adresse_ip_du_serveur>

login openvpn

password: indiqué dans le log de l'installation

screen 1: go to admin panel enter your login/password

screen2: Network settings: Activate UDP only and port 1194 then save settings

screen3: VPN Settings: enter the fields as in the screenshot and then save settings

screen 4 et 5: User Management/User permission : change the password in local password and enter the fixed ip adress on the screenshot and then save. Then update running server.. 
To reconnect to the configuration interface : https://adresse_ip_du_serveur:943

screen 6: User Management/User profile: click on new profile then click on create profile. Rename the downloaded configuration file as openvpn.conf Open the configuration file and find the line auth-user-pass and replace it with the following line: <blockquote>auth-user-pass auth.txt</blockquote>

Configuration of orangepi/raspberrypi Then launch on the orange pi and raspberry pi : <blockquote>sudo apt update && sudo apt install openvpn</blockquote>

Copy the downloaded configuration file to /etc/openvpn/client/openvpn.conf on your orangepi/raspberry pi create a file auth.txt in /etc/openvpn/client/ in which you copy the two following lines replacing password with your password <blockquote> openvpn password </blockquote> Lancer ensuite le client vpn:
<blockquote>sudo systemctl start openvpn-client@openvpn</blockquote> If you want the client to connect automatically at the start of your machine type <blockquote>sudo systemctl enable openvpn-client@openvpn</blockquote>

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To redirect the requests on the server to the orangepi/raspberry pi, we put in place a http nginx server

<blockquote>sudo apt install nginx -y</blockquote>

We then open the configuration file of this http server:

<blockquote>sudo nano /etc/nginx/sites-enabled/default</blockquote>

Replace the content of this file with what follows

<blockquote>server {

listen 80;

server_name localhost;

server_tokens off;

add_header Permissions-Policy "accelerometer=(),autoplay=(),camera=(),display-capture=(),document-domain=(),encrypted-media=(),fullscreen=(),geolocation=(),gyroscope=(),magnetometer=(),microphone=(),midi=(),payment=(),picture-in-picture=(),publickey-credentials-get=(),screen-wake-lock=(),sync-xhr=(self),usb=(),web-share=(),xr-spatial-tracking=()";

add_header Strict-Transport-Security "max-age=31536000 ; includeSubDomains";

add_header X-Frame-Options "SAMEORIGIN";

add_header X-Content-Type-Options nosniff;

add_header Content-Security-Policy "script-src 'self';";

add_header X-Permitted-Cross-Domain-Policies none;

add_header Referrer-Policy no-referrer;

add_header Clear-Site-Data "cache,cookies,storage";

location / {

proxy_pass <nowiki>http://10.10.0.2</nowiki>;

proxy_set_header Host $host;

proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

proxy_set_header X-Real-IP $remote_addr;

proxy_set_header X-Forwarded-Proto $scheme;

client_max_body_size 20M;

limit_except GET HEAD POST {deny all;}

}

}</blockquote>

Nginx will redirect all requests made on the public ip of your server to your orangepi/raspberry pi nextcloud (line proxy_pass <nowiki>http://10.10.0.2</nowiki>;)

you can test if this works when going on the page:

http://ip_publique_de_votre_serveur_gandi/nextcloud

(note it's http and not https)

Watch out, many navigators dont accept very well the http redirections, see https section to configure https (it will need a domain name)

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the domain name is the adress in your navigator: for example lowtechlab.org

It will allow you to have your server reachable more easily with an adress you can remember. It only associates the domain name and the ip adress of your vpn server or
the ip adress of your box.

Wether you register a domain name to redirect to your ip adress or not (it's necessary to get the https however), we must note that by default, the internet providers give you
a different ip adress on each connection.

If you want a fixed ip adress, you will have to ask your internet provider. It is unfortunately not very well spread in the mainstream internet packages. Orange offers instead a "Dyndns" that allows to have a correspondance in letters to your ip but with which you can not attach easily a domain name. A few domain name registrar like infomaniak, offer however to register a domain name for the dyndns which is easily reachable without extra cost on most operators.

If you have a 4G internet connection, it is not possible to get a fixed ip and your public ip is usually a"pool" ip. That is to say that the operator gives you a public ip adress which is shared among several clients, and doesnt allow you to use the NAT/Port Forwarding technique to have your dietpi available on the internet.

You will then have to take a domain for your vpn server that redirects the requests to your dietpi.

See image attached for the recording of a domain: it is the line "@" type A you have to fill with the public ip adress of your box or your vpn proxy server.

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If you have a proxy server

On your gandi server, do the following :

Create a file /etc/nginx/conf.d/dietpi.conf and paste the following lines:

<blockquote>server {

listen 80;

server_name localhost;

server_tokens off;

add_header Permissions-Policy "accelerometer=(),autoplay=(),camera=(),display-capture=(),document-domain=(),encrypted-media=(),fullscreen=(),geolocation=(),gyroscope=(),magnetometer=(),microphone=(),midi=(),payment=(),picture-in-picture=(),publickey-credentials-get=(),screen-wake-lock=(),sync-xhr=(self),usb=(),web-share=(),xr-spatial-tracking=()";

add_header Strict-Transport-Security "max-age=31536000 ; includeSubDomains";

add_header X-Frame-Options "SAMEORIGIN";

add_header X-Content-Type-Options nosniff;

add_header Content-Security-Policy "script-src 'self';";

add_header X-Permitted-Cross-Domain-Policies none;

add_header Referrer-Policy no-referrer;

<nowiki>#</nowiki>add_header Clear-Site-Data "cache,cookies,storage";

return 301 <nowiki>https://$host$request_uri</nowiki>;

location / {

return 301 <nowiki>https://$host$request_uri</nowiki>;

}

}</blockquote>

Then launch the following commands:

<blockquote>sudo apt install letsencrypt
 
wget <nowiki>https://raw.githubusercontent.com/certbot/certbot/master/certbot-nginx/certbot_nginx/_internal/tls_configs/options-ssl-nginx.conf</nowiki>
 
sudo cp options-ssl-nginx.conf /etc/letsencrypt/options-ssl-nginx.conf
 
wget <nowiki>https://raw.githubusercontent.com/certbot/certbot/master/certbot/certbot/ssl-dhparams.pem</nowiki>
 
sudo cp ssl-dhparams.pem /etc/letsencrypt/ssl-dhparams.pem
 
sudo rm /etc/nginx/sites-enabled/default
 
sudo apt remove certbot
 
sudo apt install python3-certbot-nginx</blockquote>

obtain the certificates (replace __domain__ with your domain)

<blockquote>sudo certbot certonly --nginx -d __domain__</blockquote>

then copy the following lines in your file /etc/nginx/conf.d/dietpi.conf

replacing __domain__ by your domain

<blockquote>server {

listen 80;

server_name localhost;

server_tokens off;

add_header Permissions-Policy "accelerometer=(),autoplay=(),camera=(),display-capture=(),document-domain=(),encrypted-media=(),fullscreen=(),geolocation=(),gyroscope=(),magnetometer=(),microphone=(),midi=(),payment=(),picture-in-picture=(),publickey-credentials-get=(),screen-wake-lock=(),sync-xhr=(self),usb=(),web-share=(),xr-spatial-tracking=()";

add_header Strict-Transport-Security "max-age=31536000 ; includeSubDomains";

add_header X-Frame-Options "SAMEORIGIN";

add_header X-Content-Type-Options nosniff;

add_header Content-Security-Policy "script-src 'self';";

add_header X-Permitted-Cross-Domain-Policies none;

add_header Referrer-Policy no-referrer;

<nowiki>#</nowiki>add_header Clear-Site-Data "cache,cookies,storage";

return 301 <nowiki>https://$host$request_uri</nowiki>;

location / {

return 301 <nowiki>https://$host$request_uri</nowiki>;

}

server {

listen 443 ssl http2;

server_name localhost;

server_tokens off;

ssl_certificate /etc/letsencrypt/live/__domain__/fullchain.pem;

ssl_certificate_key /etc/letsencrypt/live/__domain__/privkey.pem;

include /etc/letsencrypt/options-ssl-nginx.conf;

ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;

add_header Permissions-Policy "accelerometer=(),autoplay=(),camera=(),display-capture=(),document-domain=(),encrypted-media=(),fullscreen=(),geolocation=(),gyroscope=(),magnetometer=(),microphone=(),midi=(),payment=(),picture-in-picture=(),publickey-credentials-get=(),screen-wake-lock=(),sync-xhr=(self),usb=(),web-share=(),xr-spatial-tracking=()";

add_header Strict-Transport-Security "max-age=31536000 ; includeSubDomains";

add_header X-Frame-Options "SAMEORIGIN";

add_header X-Content-Type-Options nosniff;

add_header Content-Security-Policy "script-src 'self';";

add_header X-Permitted-Cross-Domain-Policies none;

add_header Referrer-Policy no-referrer;

<nowiki>#</nowiki>add_header Clear-Site-Data "cache,cookies,storage";

location / {

proxy_pass <nowiki>http://10.10.10.2</nowiki>;

proxy_set_header Host $host;

proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

proxy_set_header X-Real-IP $remote_addr;

proxy_set_header X-Forwarded-Proto $scheme;

client_max_body_size 20M;

limit_except GET HEAD POST {deny all;}

}

}</blockquote>

restart nginx

<blockquote>sudo systemctl restart nginx</blockquote>

Once you have completed these steps, your server is reachable online in https typing in your browser https://votre_domaine/nextcloud

Vous pouvez alors configurer nextcloud en ligne par le compte administrateur
login par défaut sur dietpi: admin
mot de passe par défaut sur dietpi: mot de passe entrée à l'installation de dietpi

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Wether it be for ecology reasons, or any other reasons, it is interesting to have a energy offgrid server,

that will not rely on the grid hazards

NB: for a slightly modified version of the photovoltaics sizing (mean production/range based with jrc model in december instead of minimum sunlight hours) see my other tutorial here:

[[Dimensionner une installation photovoltaïque autonome]]

videos:

beginner basis (pannels, regulator, inverter, consumption/production): https://www.youtube.com/watch?v=8Ft4XQj9lQ4

simple myshop solaire kit assembly for 230V:  https://www.youtube.com/watch?v=SvmPEhPq_S8

ready for use kits (if you have subsidies and colleagues who cooperate well):

https://allo.solar/kit-solaire-1650w-230v-autoconsommation-aps.html?gclid=EAIaIQobChMIkY_fxvu-gAMVyLfVCh014gadEAYYASABEgJd8_D_BwE

integrated energy storage  (expensive and not very lowtech)

Portable energy station : 230V BLUETTI AC200MAX

EcoFlow River 2 pro

semi lowtech kits (the one used in this guide):

120W photovoltaics pannels and lead acid car battery.

really lowtech kit:

build lithium battery from waste: see barnabé chaillot on youtube

https://www.youtube.com/watch?v=_hwj7Ds50lU

basis recall: plugging in serie (+ on + and - on -) we add voltage and we keep same amperage, plugging in paralell (+ on +, - on -) we add amperage and we keep same

same for batteries: keep in paralell to keep the same voltage

the first problematic in lowtech photovoltaics offgrid is sizing (see other tutorial

[[Dimensionner une installation photovoltaïque autonome]])

To do so you will find a lot of information on the web.

You can use the libreoffice calc sheet attached to this tutorial for a diy sizing

Sizing-daily need:

Orangepi consumes approx. 20W

An additional usb hard drive consumes approx. 5W

A 4G modem consumes approx. 5W

So a constant need of approx 35W taking 16% of error margin

The daily need for a 24h powered server is approx: 35W*24=840Wh

The daily need for a server working by day only is :

in summer: 35W*14h=490Wh

in winter: 35W*8h=280Wh

Note this is a mean daily need and if you want to size

for varying needs, it is recommeded to proceed more precisely

calculating real time needs

Battery sizing based on autonomy time:

Estimate loss to 20% and increase the needs in consequence:

need 24h=840/0,8=1050Wh

Estimate wanted autonomy time:

example 24h

We will size batteries to hold 24h

For 12V batteries: 1050Wh/12V=87,5Ah

Considered we want to limit battery discharge to 50% we will get:

87,5Ah/05=175Ah

So 2100Wh in 12V

Based on the pannel characteristics (see calc sheet), we can estimate battery charging when the sunlight is minimal (in december)

Sizing with "full charge in x day" method:

If we want to be able to charge the batteries in one day in winter, we must consider the power produced by your pannels a day in winter with the less sunlight

If we take 3,5h for the minimum, the number of necessary pannels of X Watt will be:

C_battery: battery capacity in Wh

In our example 2100Wh

T_winter: minimum daily need in winter (in h)

In our example 3,5h

B_winter: daily need outside of sunlight time in winter (Wh)

in our example: (24h-3,5h)*35W=897Wh

n_wanted: number of wanted days to fully charge the batteries

in our example 1

I: output amperage of a pannel

in our example 7A

U: output voltage of a pannel

in our example 12V

Nb_pannels=C_battery+B_winter*n_wanted/T_wanted*I*U*n_wanted

In the example:

nb_pannel=(2100+897*1)/(3,5*12*7*1)

We will therefore need 10 pannels of 84W 7A in 12V

Notice the cardinal value here is at line 42 of the attached file, it is

daily minimal sunlight in december at nominal production. Reference values can be found at

<nowiki>https://re.jrc.ec.europa.eu/api/v5_2/seriescalc?lat=44.203142&lon=0.616363&loss=14&angle=45&aspect=0&startyear=2005&endyear=2005&pvcalculation=1&peakpower=1&pvtechchoice=crystSi&browser=0&outputformat=csv</nowiki>

But nothing compares to an empirical measurement to verify all that.

The graph in illustrationg comes from monitoring two 400km away installations from an entreprise who install and monitors photovoltaics since 2018. I'm waiting to measure all that with a reliable voltmeter on different second hand pannels to update this tutorial in december! :)

Any comment and feedback is welcome on this matter at the bottom of this page!

Sizing with try and errors method

The calc sheet offers at lines 41 and 42 to adjust the number of pannels and the mean sunlight time in december and gives the daily need outside of sunlight time in winter (Wh) and the maximum battery charge in winter (Ah and Wh). Doing try and errors on these two parameters, we can get the minimum number of pannels so the battery
get charged positively in winter.

The main problematic of lowtech photovoltaics offgrid is how to store the energy.

You can read the pannel characteristics :

-peak power: they add up to obtain the necessary power found when sizing

-voltage: 12V,24V or 48V. see serie/paralell rules to add up

-amperage: varying among the models but often below 10A. see serie/paralell rules to add up

To charge batteries, in principle, if you connect the pannels directly on a battery, you only need the output pannel voltage is the same as the battery so it gets charged

There is one important component you have to think about to charge correctly your batteries:

the regulator or charging controler

Three types exist: the tor (everything or nothing), the mppt (maximum power point tracking) and the pwm (pulse width modulation)

They are built with a DC/DC adapter (direct current to dirrect current) and a circuit breaker. The mppt also has an impedance adapter (it has a resistance to adapt amperag injected in the battery). the mppt accept higher nominal power, ie higher tensions and intensity

The regulator or charging controler mainly allows to break the circuit when the battery is fully charged surveilling voltage and amperage charge levels. It breas the circuit if their values get higher than the reference range (so the charging regulator stops the charge temporarily and measures the voltage at the battery)

The mppt has an integrated "electronic algorithm" that seeks the optimal power point thanks to its impedance adapter.

If you connect several pannels and several batteries, it is recommended to have a regulator to break the charging circuit correctly when the battery is fully charged.

The charging reference voltage is 12V,24V and 48V.

However, the model prices get higher with the nominal power (that will depend on amperage) they accept

To limit amperage and photovoltaics production, it is better to use higher power pannels which generally have higher voltage output

recall: P=U*I

recall E=P*t and is kept equal in a closed system).

notice: if the storage system with batteries or the device connected to your pannels doesnt absorb all the produced power, and if the charging regulator doesnt cut the circuit, the rest will be outputed as heat.

Amperage will also depend on the battery capacity, sized so as to cover your needs for a period defined at sizing.

The charge amperage is calculated dividing by 4 or 5 the nominal capacity of the battery expressed in Ah that should then discharge in 4 or 5h. However a battery will also charge with a charge amperage calculated as nominal battery capacity divided by 20 but more slowly (in 20h).

Sizing and/or arranging your pannels in consequence.

Pannel arrangements can allow to adjust voltage and amperage

There is finally a last point on which i would like to bring attention to: the trigger of the battery charging by the charging regulator (that triggers if the voltage of the battery
goes below a treshold).

Indeed, if the power taken from the battery is too low, it is possible the necessary time to discharge the battery with your daily consumption to trigger the charge in the
regulator goes longer than the daily sunlight time. Then the battery won't charge during the day.

In that case, the battery will charge every other day (depending on the charging regulator treshold)

It is a parameter to take into account in the sizing (not included in the calc sheet)

The regulator has 3 phases:

1.bulk: the regulator let the current pass

2.floating: the regulator switches open and closed at a given frequency to maintain the battery charged

In addition some precautions must be taken because charging batteries can be risky

3.absorption (for mppt): the charging voltage raises a bit to create enough potential difference to continue charging the battery which is almost full.

In theory, the charging current goes low when the battery is almost fully charged (queue current etc.)

Charging the batteries in paralell or in serie on old batteries that do not have the same amperage or voltage is theoretically risky. Indeed, you can read a bit everywhere on the web that the wire resistance to link them

creates potential differences between the batteries producing discharges from one battery to another, etc.

creating risks of explosion, degassing for lead batteries, etc.

We have to remember batteries are assemblies of unit components of weak voltage put in series and in paralell to obtain a generator of a given amperage and tension and therefore doing the same with entire batteries is not really risky...

We often talk of battery management system (bms) "integrated" for lithium ion batteries.

In reality the charging regulator is already a "bms". In theory, the integrated bms makes sure the intensity and voltage of each unit of the battery is the same and balances them at need

We can of course wonder if all this is not a way to make energy storage more expensive with bms components artificially expensive and if this is not a way to avoid to reuse old batteries.

It is amazing no bms exist to balance automatically old lead acid batteries, which would make reusable all old car batteries of the car industry to store energy without risks

In any case, if you reuse old lead acide batteries, use a charging regulator to avoid continuing charging your already charged batteries (hydrogen production risk) -or if you dont use a regulator, size with a lot of precaution-, avoid profound discharges, and maintain the batteries at a constant temperature as much as possible.

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We begin sizing on 1/10 of the peak power of the pannels and 1/4 of the storage capacity given by the theoretical calculations to be offgrid 24h/24h and able to charge in one day in winter, so a pannel of 120W and an old car battery of 45Ah in 12V.

It's ok with a lowtech thinking to have the server only run when it's daylight, and for computers respecting human temporality.

To be ok in winter (hypothesis : a mean of 3,5h of sunlight), we would need a battery of more than 58Ah, but for budget reasons, we do with what we have! :)

The charging regulator doesnt accept 40V pannels so we did not use the second hand 180W pannel at 20€ found on leboncoin, but i will update this tutorial with assembly of pannels and batteries as soon as i will have the material and with the winter production digits if i manage to!

Assembly stages

Plug an electric cable to the + of the battery and to the + of the pwm regulator (battery output). Plug an electric cable to the - of the battery and to the - of the pwm regulator (battery ouput)
 
Plug the pannels to the mc4 cables. Plug the nude cable + to the + of the pwm regulator (input pannels). Plug the nude cable - to the - of the pwm regulator (input pannels).
 
Plug the pliers of the 12V/5V usb converter with the + on the + and the - on the -
 
Plug a rj45 cable of your box or your 4g modem to the orangepi or raspberry pi
 
Plug the usb cable of the orangepi or raspberry pi to the 12V/5V usb converter
 
To automate a switch to power when it's daylight and switch off when it's night, you can use a DRL module (daytime running light) of a car. The module is a switch that lets
current pass when the tension is higher than 13V (when the solar pannel is charging the battery). The switch must be plugged to the + of the IN and to the + of the battery, to the - of the IN on the - of the battery, + of the OUT on the red plier and - of the OUT on the red plier (between the battery and the 12V/5v USB converter)

Wait a few minutes that it boots. And here we are, the nextcloud server is available online! :)

Notice that if you want to power something in AC 220V, the only thing that is missing in this assembly is a DC/AC converter that we easily find in camping shops or on leboncoin.

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At a security level, the known flaws of the cpu can be found under linux doing:

<blockquote>grep -r . /sys/devices/system/cpu/vulnerabilities</blockquote>

This command on the orange pi (cpu CortexA55) with dietpi installed gives: <blockquote> /sys/devices/system/cpu/vulnerabilities/spectre_v2:Mitigation: Unprivileged eBPF enabled

/sys/devices/system/cpu/vulnerabilities/itlb_multihit:Not affected

/sys/devices/system/cpu/vulnerabilities/mmio_stale_data:Not affected

/sys/devices/system/cpu/vulnerabilities/mds:Not affected

/sys/devices/system/cpu/vulnerabilities/l1tf:Not affected

/sys/devices/system/cpu/vulnerabilities/spec_store_bypass:Mitigation: Speculative Store Bypass disabled via prctl

/sys/devices/system/cpu/vulnerabilities/tsx_async_abort:Not affected

/sys/devices/system/cpu/vulnerabilities/spectre_v1:Mitigation: __user pointer sanitization

/sys/devices/system/cpu/vulnerabilities/retbleed:Not affected

/sys/devices/system/cpu/vulnerabilities/srbds:Not affected

/sys/devices/system/cpu/vulnerabilities/meltdown:Not affected
</blockquote>

After a few tests on the orange pi a raspberry pi and a odroid, the problem is the same basics:

we can spend a whole life trying to raise security of a computer system...

finding the good tradeoff and evaluate the risks or lure of profits.

hack is always possible, and considered the number of 0day flaws never published, on any operating system, the question is less to have a flawless system, that to know from which you want to protect from when we talk about "securing" or reducing attack surface.

I think the opensource/libre philosophy is superior in terms of security because auditable and fixable by the "commu", but we must say the default settings are not tip top because linux was thought to be stable at the start (rememeber all the blue screens in windows 30 yerars ago), and not "secured".

After undergoing many hacks i consider very advanced and not in the reach of the script kiddie (and on any operating system any machine and any securing level i tried except from kernel compilation), I have tried to secure my digital stuff and i am now at the point i think "digital soveranignty" doesnt exist or not anymore.
the flaws create a security market, it makes people work... see interesting article of w0nderfall on the subject of security under linux: https://wonderfall.space/linux-securite

However, a few elements because it is a subject on which i havent found much didactic information gathered.

-limiting attack surface principle <nowiki>:</nowiki> general principle, securing only diminishes the potential attack surface

-secured physical access and related software configuration

- physical access: up to you

-grub password launch in a terminal: <blockquote>grub-mkpasswd-pbkdf2</blockquote>

Copy the text starting with grub.pbkdf2.sha512.10000.xy

where xy is a long string of letters and digits

Add the following lines to the file /etc/grub.d/42_pw

replace user by your username in linux and pw by the

text previously copied
<blockquote>

cat << EOF

set superusers=user

password_pbkdf2 pw

EOF
</blockquote>
Then launch command

<blockquote>update-grub</blockquote>

-good passwords in general

to change the user password type

<blockquote>passwd</blockquote>

to change the root user password type

<blockquote>sudo passwd root</blockquote>

-optionnally verify boot integrity (see purism computers for example)

-encrypt your storage:

https://doc.ubuntu-fr.org/tutoriel/chiffrer_ses_donnees

https://www.dwarmstrong.org/remote-unlock-dropbear/

sécurity of a server:

-automated apt update : https://www.linuxtricks.fr/wiki/debian-activer-les-mises-a-jour-automatique-avec-unattended-upgrades

-reinforced ssh :

lines to include in your ssh configuration (/etc/ssh/sshd_config): <blockquote>

Port 22 #change on other port if you want

Protocol 2

PermitRootLogin no

StrictModes yes

PermitEmptyPasswords no

X11Forwarding no

Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr

MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256,umac-128@openssh.com

KexAlgorithms curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group-exchange-sha256

AllowTcpForwarding no

MaxSessions 1

UsePAM yes

AllowUsers user #remplacer par les utilisateurs autorisées

AllowGroups group #remplacer par les groupes autorisés

PasswordAuthentication no

AuthorizedKeysFile .ssh/authorized_keys
</blockquote>

-software firewall:

ufw: https://doc.ubuntu-fr.org/ufw

or iptables configuration file:

https://gitlab.com/aurelpere/bp028-hardening/-/blob/main/rhel_iptables_ipv4/files/server_firewall.sh

-backup: 321 rule: 3 copies, 2 different storage types, 1 copy on another place than others. borgbackup stays a standard for its reliability in the free software community (i confirm after testing several stuff) and offers a cloud which is not expensive to have "remote" backups and invest money in free software development.

fail2ban: https://doc.ubuntu-fr.org/fail2ban

fail2ban for nextcloud: https://tuxicoman.jesuislibre.net/2015/01/fail2ban-pour-owncloud-7-sur-debian-jessie.html

-deactivate ipv6 (or configure the firewall as well for ipv6)

3 methods to deactivate ipv6:

1.in grub

2.with sysctl

add the following lines to /etc/systcl.conf <blockquote>

net.ipv6.conf.all.disable_ipv6 = 1

net.ipv6.conf.default.disable_ipv6 = 1

net.ipv6.conf.all.router_solicitations = 0

net.ipv6.conf.default.router_solicitations = 0

net.ipv6.conf.all.accept_ra_rtr_pref = 0

net.ipv6.conf.default.accept_ra_rtr_pref = 0

net.ipv6.conf.all.accept_ra_pinfo = 0

net.ipv6.conf.default.accept_ra_pinfo = 0

net.ipv6.conf.all.accept_ra_defrtr = 0

net.ipv6.conf.default.accept_ra_defrtr = 0

net.ipv6.conf.all.autoconf = 0

net.ipv6.conf.default.autoconf = 0

net.ipv6.conf.all.accept_redirects = 0

net.ipv6.conf.default.accept_redirects = 0

net.ipv6.conf.all.accept_source_route = 0

net.ipv6.conf.default.accept_source_route = 0

net.ipv6.conf.all.max_addresses = 1

net.ipv6.conf.default.max_addresses = 1
</blockquote>

3. with network manager nmcli

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/configuring_and_managing_networking/using-networkmanager-to-disable-ipv6-for-a-specific-connection_configuring-and-managing-networking

-secure the server in case multi user or when a user accessed the server

lists of files to secure (permissions etc.): https://linuxfr.org/forums/linux-general/posts/liste-des-fichiers-linux-a-securiser-owner-group-permissions-setuid-setgid-sticky-bit

guides to harden:  https://www.ssi.gouv.fr/guide/recommandations-de-securite-relatives-a-un-systeme-gnulinux

To go further in terms of security:

free physical firewall: pcengines/ free software OPNSense

fail2ban with geography lists: https://thecustomizewindows.com/2016/11/fail2ban-geoip-action-script-block-ssh-country/

Create a connection sas to your online service (MySafeip): https://linuxfr.org/news/mysafeip-un-tiers-de-confiance-pour-votre-pare-feu

secure the systemd linux services:  https://github.com/juju4/ansible-harden-systemd

compile a kernel :

[https://doc.ubuntu-fr.org/tutoriel/comment_compiler_un_kernel_de_kernel.orghttps://github.com/robertdebock/ansible-role-kernel https://doc.ubuntu-fr.org/tutoriel/comment_compiler_un_kernel_de_kernel.org]

[https://doc.ubuntu-fr.org/tutoriel/comment_compiler_un_kernel_de_kernel.orghttps://github.com/robertdebock/ansible-role-kernel https://github.com/robertdebock/ansible-role-kernel]

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Notes and references

No thank you, it was difficul and i was not helped ;) The tutorial and its content are not based on expertise or specific training but from diy and information gathered on the web, so please be indulgent ;) feedback welcomed in comments

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