Choosing a system is generally based on a number of criteria
Our thoughts on this are that your controller is at the heart of the system and not easily changed. We strongly recommend the EPEVER 4th generation dual charging system. This charges not only the domestic side, it also trickle charges the starter battery.
Our system heart is the EPEVER DR3210, this controls a large 30 amps inc 1 amp for the starter. We include this
You can specify 2,3 or 4 solar panels, with our kits, if budget is your main concern start with 2 panels and this controller can cope with the increases in solar panels.
Likewise with batteries – you will always want more, but you can start with one leisure battery and increase the number.
- How economical are your devices on the boat?This is probably the most important consideration. A well configured boat for off grid living will be largely 12v based and should have a 12v fridge, probably 12v sockets for charging devices up and likely a 12v TV and LED lighting. This is kind of a “perfect” configuration making no use of an inverter to generate mains which requires a lot more power. This perfection comes at a price.Most boats however will require some use of an inverter perhaps just for a TV which is not too bad (all mains electronic devices these days are fairly low power draw and although not as efficient as running 12v units they do not place massive loads on an inverter) but often for a mains powered fridge which is much more “amp hour” hungry and sometimes a mains powered freezer too. Part of the process is calling for a chat so I can find out what you are running and make a recommendation on system size. Basically the more power you draw (and inverter based mains kit draws a lot more) then the more solar you will need. Sometimes it might be better to rethink your power draw and change things for lower voltage equipment then have less solar! *NOTE* THAT REFRIGERATION IS THE BIGGEST ISSUE AS IT IS ON 24 HOURS A DAY. NO MATTER HOW ECO A 240 FRIDGE IS IT WILL ALWAYS BE FAR MORE POWER HUNGRY THAN A 12V FRIDGE DUE TO 24 HOUR INVERTER USE AND THE POOR EFFICIENCY OF TAKING 12V AND STEPPING UP TO 240V.
- Battery bank size The battery bank size also dictates the amount of solar required to ensure its topped up on a daily basis – again the bigger the bank the more solar is required. One very common issue I come across on a regular basis is banks that are way too small. The customer is anxious to get solar as they struggle on a daily basis with power. On chatting through I find they only have two 100 ah batteries and are trying to keep a fridge going and run a TV lights etc. So you may need to have a look at your battery bank size as well.
- What type of user are you? Are you just an occasional holiday boater non live aboard? Are you continuously cruising? Are you living on a linear mooring with no power? These are the kind of questions that will again drive you towards the right system. A holiday boater only wants the batteries to be topped up when they get to the boat and is unlikely to stay somewhere on their travels for long so probably only needs small scale solar. A continuous cruiser needs power on a daily basis but mixes cruising with stopping for a few days. So a good solid mid range system is often best. The boater living on a linear mooring with no power needs the larger system as they are not wanting to run and engine every day just to generate power.
- Budget As always budget comes into it. In all truth you can never have too much solar as the controller backs off once it’s done its job. The more you have the quicker the batteries top up and the more you can draw. So if you want to be totally safe and secure that you have enough power then over specifying the system is the way to go.
So in choosing a system it is a little bit like the “how long is a piece of string” argument as we have to weigh up the 4 factors above.
Generally these are the systems chosen.
- Holiday boat and/or primarily marina based using the boat every now and then and assuming it’s fairly 12v orientated. Then the 430w 2 panel is a good option.
- Live aboard continuous cruisers tend to go for the 3 panel 645W system. This is an excellent all round system that will output a charge rate of 40A on a reasonable spring or summer day but with a good high average on the worst of days. While I would still always recommend 12V refrigeration this system does support a 240V fridge with inverter run 24 hours well as long as your battery bank is capable.
- Live aboard boats on moorings with no power such as linear moorings have the greatest challenge in that they are not naturally needing to move often and so really want to minimise or eliminate engine run time so the larger 4 panel 860W system, with the larger 60A controller is the usually the best way to go, guaranteeing a good high average output in most conditions.
- Large wide beam barges off grid with largely 240V systems. The other category for larger systems tend to be large barges with heavy 240v usage and/or very large battery banks. In these instances the 860W system with 60A controller is the likely minimum but consideration of a larger custom designed Bespoke System is usually the best way forward.
Remember that the more solar wattage you have the higher your average daily output will be and thus the need to monitor and be more “careful” with power reduces considerably as the system size increases. In short – You can never have too much solar – but you can easily have to little.