Solar Panels for Boats
Offgrid living experience
8 years living full time long distance cruising on a yacht.
Installation experience
15 years solar installation experience.
Passionate
We love what we do, which is reflected in the quality of our service.
Thinking of joining the Atlantic Rally for Cruiser (ARC) or wanting the security of backup solar power for weekend trips, we are in a unique position to give expert advice on your solar system. Please call us for advice on 01803 446 109. – we love talking solar and boats.
Integrated hard bimini
Hard bimini and davits
Custom behind hard bimini
Adjustable stanchion
Flexible solar panels
- Ideal for mounting permanently flush on the deck or sewed into a bimini.
- Can be a temporary solution when at anchor and moved to optimise solar generation.
- Choose panels with stainless steel grommets - most flexible solar panels have copper grommets which corrode quickly and can cause panel delamination.
- ETFP top surface - the alternative PET top surfaces do not bond as well to the substrate and are prone to delamination.
Rigid solar panels
- Ideal for mounting permanently on the davits, poles, arches or on rails.
Things to consider
- Quality - most rigid solar panels, including ones for use on houses, are suitable for mounting on a boat. Many have been tested for corrosion due to salt mist.
- Weight - rigid solar panels tend to be quite heavy. Two 360W panels and mounting frames can weigh 50kg so check if your davits or mounting systems are designed for this extra load. Also consider the trim of the boat.
- Fixing method - the loads on a solar panel can be significant on a boat. Make sure they are adequately fixed and supported.
Flexible solar on bimini
Pole mounted solar panels
Deck mounted solar panels
Hard bimini
Charge controllers and the harsh marine environment
- Choose a solar charge controller with a high IP rating. The IP rating might be a good indicator of longevity on a boat.
- Only use MPPT charge controllers since they are designed to reduce energy loss in shade conditions - shade is almost unavoidable on yachts.
IP30
SRNE HP2410
0 - No protection
IP43
Victron MPPT 75/10
3 - Sprays at 60° from vertical
IP67
Lumiax MPPT1050
7 - Immersion at 1m for 30 minutes
Design for shade
In the example below it shows 30% shade reduces output by 30% but surprisingly 30% shade can impact solar output by up to 80%. Try to minimise shade through careful positioning of the solar panels. The example shows the benefit of having multiple solar charge controllers – it also has the benefit of resilience should one solar system stop working, you still have power.
Lithium batteries
- Lithium batteries can absorb more energy from solar. For example, a 1,000 watt solar system may charge lead acid batteries at 600 watts but lithium batteries at 800 watts.
- You may be able to run high load devices such as windlasses and winches without starting the engine. A great safety feature.
- You might be able to avoid having gas on the boat by using induction hobs instead.
Wiring
- Joining cables is the most common reason for solar system failure. Try and join the solar cables below deck or use MC4 cable joiners which have been crimped with the correct tools.
Best solar panel and lithium design for boats
The below is a simple design for installing on boats with jump start capability. All the flows work whether you are anchored, motoring, sailing or at a marina. It also works for storing the lithium batteries – see the section below “Storing lithium (LiFePO4) batteries on boats”.
Storing lithium (LiFePO4) batteries on boats
- Store lithium battery at 50% charge.
- Isolate lithium battery from all loads and charging sources.
- Keep the lead acid starter battery topped up with a small solar panel and a cost effective PWM charge controller.
