You are probably a typical boater in that everything is fine while continuously cruising or plugged in, but when you want to sit somewhere on the cut for a few days you don't want to be running your engine for hours on end! So is solar the answer? The answer to that question is YES, it's PART of the answer. First and most important thing to understand is solar does not mean you can forget about the problems and have an abundant supply of power. You STILL need to be just as economical with your power as you usually are BUT if you are, you won't need to run your engine - possibly at all!

So what else should I think about?

The key secret to living off grid and relying on a 12v battery bank as your source of all power is to run as MUCH as possible at 12v. So in an ideal world a 12v fridge, 12v TV (some very good flat screen with integrated DVD ones available now not like the “old” days) and have 12v sockets allowing car charges to be used for all our modern technology such as mobile phones and tablets etc. The other great new technology is LED replacement bulbs that so sums next to nothing (see below). Most boats will have Inverters fitted that generate 240v mains power from your batteries and whilst useful do be aware that they consume a lot of power in providing that 240v and thus running even the most economical of mains powered devices such as a lap top charger consumes a lot of power. Any 240v object that's heats up should be avoided wherever possible as heating elements consume sometimes 200 amps or more… The most common heavy duty mains device is a wahing machine. The trick here is to use the inverter BUT while the engine is running a high rate of charge is being delivered from the engine alternator to “offset” the high rate of discharge through the inverter. Below are a number of key tips to “eco” your boat..

  1. Fridges are the biggest draw on a 12V boat. Do you have a 12V fridge? Many boats opt for 240V fridges on account of the fact that they are a lot cheaper to buy. Whilst in a marina and plugged into the mains this is no problem, however to keep a 240V fridge going while on the cut means an inverter has to be switched on for 24 hours a day to generate the "mains" to run it. This is very power hungry. As a rule of thumb a 12V fridge consumes about 4 Amps while the compressor is running. A 240V fridge will consume about 8 Amps, while the compresseer is running PLUS the inverter load of between 1 and 2 amps 24 hours a day. I have an excellent company I recommend for 12V fridges. They buy in domestic fridges and convert them to 12V and have a huge range of options. One of my favourites is an under counter fridge/freezer with two doors - a small freezer door and a larger fridge door. A great unit - I have one myself. For further details contact Inlander 12V (telephone 0121 421 2555)
  2. During your installation I am happy to take a look at your light fittings and advise of suitable replacement LED’s and give you online sources from where you can buy.
  3. Have 12V sockets and charger. Most modern electronic stuff is low voltage, though possibly not 12V. Most boaters switch the big inverter on and have laptops, phones etc plugged into 13A mains outlets on the boat. Whilst this works it is very inefficient. Far better to have 12V sockets (very common on older boats, but not so on new ones). You can then purchase car chargers for your phones and laptop and charge DIRECTLY from the 12V with no inverter required. It makes a huge difference! Of course there are some great 12V TV's available now too which consume tiny amounts of power.


Try to get to a point where you don't need to reply on mains power via the inverter as MUCH as possible. Of course you may need to use the inverter to run heavy duty items like the washing machine, BUT you would also run the engine at the same time to make sure a big charge is going in from the altenators while you are drawing a big charge to run the inverter/washing machine. It also pays to remember the golden rule - if you don't need it - switch it off! Thus if you don't need mains at the moment, turn the inverter off. These simple tips above will make a huge difference to your life on the cut AND reduce the amount of solar you need. A boat equipped as described above will comfortably sustain itself on a 330W system. A boat with say a 240V fridge and a 240V freezer will need to consider at minimum 495W of solar and probably look at 660W to be "comfortable".