I made my blog solar-powered - a huge update

ul" class="toggle">

Home

Solar

About

Background

In 2020 - inspired by Low Tech Magazine - I decided to make this blog solar-powered. At that time, I was already self-hosting this blog on a Raspberry Pi at that time so it felt like a fun little project.

It all started with a small 60W solar panel and a few small 'motor cycle' lead acid batteries1. In part due to the sub-optimal orientation of my balcony, the 60W panel did not generate enough energy. So I added a bigger 150W panel in parallel with the 60W panel and added an old lead acid car battery, as documented in my first blog post about the project.

As this still didn't generate enough solar power to keep the Raspberry Pi running 24/7, I added two 370 Watt solar panels and a large 280Ah 12V lead-acid battery, as documented here2.

During spring and summer, the two large solar panels provided enough power to charge the battery and even run my Mac mini and dual monitor setup for many hours. So I added an inverter (converts DC to AC) to make this possible.

As this setup worked great, I decided to replace the lead-acid battery with an<br>LFP battery, which was a huge improvement.

Four 230Ah LFP prismatic cells (~2.7 kWh)

As a ship of Theseus, not a single component of that first solar setup remains3. And I'm no longer only powering the 3W Raspberry Pi hosting this blog, or just my computer and monitors.

My solar-setup now powers my apartment .

I want to acknowledge that DIY solar-battery systems is starting to become more mainstream and in that sense my setup is not special. People building DIY 1-phase or 3-phase systems with 15kWh - 64kWh+ of battery storage is well-documented on Youtube.

Yet, I think my small setup might still be interesting and I just wanted to share my build.

About my apartment

I live in an apartment in The Netherlands. I've placed two solar panels on my balcony, which is facing west. Direct sunlight only appears at around 16:00 in the afternoon, which is far, far from ideal.

This is an important limitation of my setup and the daily solar yield of the two panels would be much higher if my balcony would have faced south. I'm convinced I could run my home most of the time on solar from April until early October with just two 370W panels4.

An overview of my current setup

It's a 12V system where all components are connected to a shared busbar. It consists of two 370W solar panels, each connected to its own solar (MPPT) controller. There are two batteries based on LFP with a combined capacity of around 6kW. The inverter is grid-connected and can charge from the grid or discharge towards the grid. A 20x4 LCD display connected to the Pis GPIO pins shows some basic info.

Some 12V 'cigarette lighter' style outlets are used to charge power banks, tablets and other battery-powered gizmos. I've also used a boost-converter to power 30V DC led lights to illuminate my living room.

The shunt is a device that measures how much energy is flowing through the system and it is the most accurate device to gauge state-of-charge of the batteries. Although statistics about the batteries and individual cells can be read through bluetooth, the state-of-charge estimate of the individual BMSses (Battery Management System) isn't reliable enough.

I want to acknowledge that the wiring of my setup isn't neat or pretty, but I've done my best to keep everything safe to the best of my knowledge.

Since the last blog post about my solar setup, the following changes have been made:

Added a second MPPT solar charge controller, one for each 370W panel

Added a grid-connected inverter to keep my house energy meter at zero

I'm reading P1 energy data in real-time from my energy meter via P1

Switched from a fixed to a dynamic energy tariff for my grid connection

Added a second 280Ah LFP battery (~3.3kWh for a total of ~6kWh)

Added two 12V 25A battery chargers to speed up charging (1 visible)

Use zigbee to enable / disable the auxiliary chargers

Bought proper battery cases for the cells and BMS

Added 1W temperature sensors

These changes will be discussed in this blogpost.

Extra MPPT Charge Controller

Initially, I had the two solar panels connected to a single solar controller (MPPT 100/30) in parallel, but the output of this MPPT is limited to 30A x 12V = 360W. By adding a second solar controller - one for each panel - 576W peak power was reached in June. Adding the second MPPT clearly removed a bottleneck.

The new grid-connected inverter

By far the most important change is the new grid-connected inverter.<br>My original Victron Phoenix inverter is intended for off-grid usage only and can't be connected to the grid, so I had to replace it.

I bought the Victron Multiplus II 12/1200/50 model. This is a 12 Volt model with a max output of 1kW and can charge with 0.6kW.

The Multiplus inverter can use the grid to charge the batteries, but can also inject power back onto the grid. In other words: if your home is...