We are continuing to accumulate experience in how best to manage the off-grid energy system on our houseboat. It’s not easy!

After a long Indian summer, it has now turned wet and grey, and that is forecast to continue. Yes we have a nominal 5250w of solar panels on the roof, but in dreary conditions, actual daytime output is running between 160 and 660w. With perhaps 8 hours of light that means between 1000 and 4000w of electricity input. A flat roof is far from ideal in winter! The fridge/freezer alone uses 140w and my computer and screen, and the TV, almost the same. Basic daily consumption is certainly 5000w before using any domestic appliances.

We cook by gas and have a small compressed wood log burning stove for heating, but three on board appliances use a great deal of energy – dishwasher, washing machine, and water heater. Each is drawing around 1000w for about an hour when in use.

A 2000w genset puts about 10A back into the 9.6Kw of 48v main system batteries via a battery charger – enough to prevent too big a voltage drop for basic use. Lithiums are however too greedy to charge directly – they trip the overload on the genset. Keeping the batteries charged is therefore a challenge.

Our solution has been to buy a Bluetti AC200Max that powers my computer and the TV. Installed on the upper floor, it can be recharged either from the mains (no longer possible) or from the genset – works fine. However that does not solve the problem of power generation and being able to run the water heater and other machines. Our solution is to add 2 x 400w rigid solar panels that I may just hang from the rear balcony, but that faces east, so I may move them to the side of the house that faces south. Vertically mounted, the panels alone should keep the Bluetti charged, with 450w of help from the genset whenever running. Most of the time, I am drawing 120w and that only between 10 and 10 so 1440w in total. I have also added an extension 2Kw battery to the Bluetti, taking storage to 4Kw.

We are disconnecting the 1000w water heater that is located on the upper floor from the main 230v circuit and connecting it to a separate circuit powered by the Bluetti power station. My computer, the TV, and upper floor lighting are all being connected to the Bluetti. In addition, we are installing a switch that allows the main 230w system to be powered by the Bluetti in the event that the main system fails for whatever reason.

Technically complex installation? Yes, for sure. Expensive? No not really. Yes I bought “reconditioned” Bluetti bits but they were apparently new, plus the 2 solar panels and assorted cabling costs, so perhaps €2250 in all. If I had just added 4Kw of 48v LifePo4 battery storage that would have cost me €1200, plus the solar panels for another €250, so I have in effect spent €800 to give myself dual circuit safety, and the Bluetti recharges all the telephones and other USB or 12v devices quite faultlessly. I’m happy!