It was three years ago when I decided to jump into solar power purchasing a little Bluetti unit and experiment with it. You can read about it in this blog post from September 2023.
A few days after testing the unit, I decided I wanted to have an off-grid way of charging the power station besides using the house power and I ended up purchasing a compatible 100 watt portable panel. The unit can take only up to 200 watt from solar panels. You can read about the panels in this other post
Getting a portable solar pannel to charge the small unit
The first real test was in October 2023 when we spent a few days camping in Portugal and I soon realized it was not enough to power the small portable fridge unit we have. It ran out of power after a few hours as the fridge ventilator was running 24hr a day. Actually, small camping fridges consume more than regular home ones. This small units are good for a day out in the country side or if you need power in a place away or a home outlet but you can not ask too much more. This particular unit has 1Kw power and 730Kw/hr battery capacity and I have used it to power the pump when getting water out of the well or to power some tools when working on projects.
As we were planing to start reconstructing the tiny house on the farm I decided to purchase a bigger unit which I could use later to power the house. I chose the Bluetti AC200MAX, this one has 2Kw of power (with an initial pick up to 4kw) and 2Kw/hr battery. Here's the post I published back then.
Right after getting the new unit, we bought two 500 watt solar panels to feed the power station which can take only 900watts from the sun. I know I was exceeding the nominal 900 input with two 500 units but as those with experience know, you always overfeed the solar production as the panels hardly reach 70% of the nominal power. Actually, I have never managed to get more than 750watts from both panels and that has been only a few minutes a day. You can see the published post showing the panels here.
We have been able to get all our electricity needs from the system last two summers. We have the regular fridge connected permanently and use the water pump every day to water the trees. The unit has also been feeding all the tools needed during the construction and in the middle of the day the sunlight brings the battery back to 100% charge as most of the days are sunny during the summer so there is no worries, although I keep checking the battery situation every once in a while during the day. I was concerned about the consumption during the winter. We plan to spend a few days in the coming weeks and daylight is shorter plus there are more cloudy days so we decided to upgrade the system with an expansion battery and it just arrived today!
This is the new generation of expansion batteries Bluetti launched a couple of years ago, when they decided to get rid of most of the outlets they use to have and leave only a USB-a one in order to reduce the previous prices. They are intended to use added to a central unit as a way to increase its power capacity instead of stand alone. Our main unit, the Bluetti AC200MAX has 2KW/hr and this additional expansion battery brings us 2.7Kw/hr additional so we more than double the capacity we had. We could even add another one in the future if we do need to.
I am sure, in the summer we will get 100% capacity of both batteries with only the two 500Watt solar panels, but I will have to see how they behave in the coming days when I travel back to Portugal and plug this new battery to the system. If there are several cloudy or rainy days in a row, I may need to run the gasoline power station to feed the system Bluetti.
I know setting out a house power with portable units such as this ones is more expensive than setting up a system with panels, inverter and batteries, but internal space is something we need to consider in our tiny house and the "plug and play" solution they offer plus the portability to charge them somewhere else or bring power anywhere have solved us many problems in the past. I even plan to purchase an additional unit in the future to keep as a home backup in the event of a blackout as the one we had a few months ago in Spain and Portugal. According to the news AI data centers will increase global power consumption so much we can expect this power grid issues more often in the future.
