I'm in self isolating for the next two weeks in our old static caravan after coming home from the UK. Its got me thinking about going off grid with it as far as possible.
First of all I thought it would be nice to have a decent radio built in and having a spare nearly new 12V car radio from a recently scrapped car I though why not install that and some decent speakers. Along with the internet, Bluetooth on a mobile phone and laptop that gives me access to all the audio content I want.
I then realised that it might be easier to power the car radio (12V 10Amp) from a 12V battery than make up a power supply. OK so then I lost the plot a bit and thought if I'm using a battery why not charge it from solar panels and if I'm doing that why make the whole thing off grid.
Currently the static caravan (30ft) is connected to the mains. Heating, hot water and cooking is all gas so that eliminates some big power hungry uses for electricity. That leaves fridge, toaster, electric kettle and microwave as items that probably use more power than I may be able to accommodate. Apart from the fridge which is always plugged in, the toaster, electric kettle and microwave are only used for a few minutes a day. I'm even thinking of getting rid of the microwave as its rarely if ever use. I can dump the toaster and use the grill on the stove and similarly the kettle but I do like their convenience. Items I'd like definitely like to power from solar/battery are, LED lights for the whole caravan, laptop computer (will get 12 V psu for it), router, wireless link (PoE), TV, Security system (12v), USB charging (phones, tablets, torches), car radio (12V). A bonus would be to be able to charge 18V Dewalt XR batteries I can't find a car charger for the 4 Amp ones I use so would have to hack something.
Getting PoE working as directly from the batteries is possible an issue. I don't see the point in charging batteries, then using an inverter to power a 24V PoE adapter, but I'd like some form of charge limiting or intelligent controller for the PoE as I don't like the thought of a short at the end of a Ethernet cable being a short across the batteries - would a fuse be enough protection? The PoE is worth the effort because we are the last house on the circuit in our area and I'm connecting for the internet to a neighbor whose power comes from a different county so if we go off they often still have power.
So to start me off what is a sensible amount of power to be trying to generate and what would be a sensible amount of storage?
First thoughts are I have room for 600 Watts of panels (4 x 150Watt?) but might be able to squeeze in more and was thinking about a 24V system with either 2 x 12V 100Amp leisure batteries or 4 x 12V and having a 24 Volt system (there is plenty of well ventilated space for batteries). Which leads to the question of what charge controller? 24V seems more sensible to keep cable size down but then how do I power my 12V car radio that started me down this road?
This is a hobby project so I'm not looking for a return on investment but don't want to waste money on stuff I really don't need. I tend to be a bit excessively belt and braces so would prefer to over rather than under specify.