Log in
Article search:

Q & A

Fridge Freezer

Wide beam so space is good
I have 920 watts of solar panels and three leisure batteries connected to a 3000watt pure sine wave inverter
12volt or a 240v A+++ rated fridge freezer

Asked by: Steve Batt  | 9.45am, Sunday 19 November

WW says:

Generally it is better to have a low voltage appliance such as a fridge/freezer because it can use the boats battery supply directly without having to first convert it to 230V mains.
A compressor fridge only uses power intermittently when the temperature rises within and needs cooling; running a mains appliance means running an inverter constantly just to supply this intermittent load. A typical 3kW inverter will consume a constant 20W of power from the batteries when not supplying any mains power. Your maximum available cabin battery capacity is around 150Ahr; you obviously wish to supply a substantial amount of your power from the solar panels to avoid having to run the engine, so do you wish to use 40Ahrs per day just to keep the inverter ticking over waiting for the fridge to kick-in? The maximum efficiency of a typical 12V inverter is 93%, which means at least 7% of the battery power is lost in the conversion process, a 12V appliance will cost more but should use less power.

Rupert Smedley  | 10.42AM, Monday 20 November

Some modern inverters have an exceptionally low quiescent (standby) current- so check the draw of your inverter that you have (or are going to fit) and then do the calculations- it might be cheaper in the long term then to fit a couple of extra batteries (ideally in a seperate battery bank you can switch into) and have a 230V fridge freezer, which would be far heaper to buy. However, if your inverter is an older, less efficient model, then a 12V appliance is the better way to go.

Mark Langley  | 7.27AM, Tuesday 21 November

You must log in to post an answer.