I am in the process of trying to fit out my boat for blue water cruising and being a geek (retired) I tend to have quite a lot of electronics (not to mention the fridge and watermaker ) on board … presumably you do too or you would not be reading this 🙂
Based on my research it looks like solar panels will provide back up for me rather than become the main source of battery charge. I am sorry to have to conclude this. I hope that increasing R&D and innovation will change that conclusion in the not too distant future.
Why do I say this?… well this is my opinion (at the moment)….
- They are “green” – we all love to reduce our impact on the environment
- After initial outlay – power is free
- They are large and cause windage that affects steering and balance (as does the bimini !)
- They cause weight distribution to go higher than desirable – depending on mounting choices.
- Capital outlay is high for panels; MPPT controllers; wiring; s/s mounting frames /arches
- They are ugly!
I actually already have a Dolphin generator on board and although it hasn't had to pay its way yet (we are not live aboards yet) I think that using a generator is still the most reliable way to keep a good charge in a large battery bank (taking into account the “cons” above ). I know that generators don't last forever and there is some evidence of poor maintenance on mine (here is a nice video for debugging faults on your generator BTW). If the Dolphin is found to be duff (the manufacturer is now bust in the UK) I will probably have to change my mind and go for wind + solar setup.
I know some sailors have suggested using one of the small portable generators of the new quiet type – such as the latest Honda range (…and carry a can of petrol or 2 or 3 – yes that is a downside!). There are some videos here too of just how quiet these things are. Of course if you did this you must make sure that you have storage for petrol, a decent sized generator will us about a gallon an hour on full load, and it should also be 4 stroke not 2 stroke so you don't get nasty oil/petrol mix exhaust being vented from the boat. There is a nice comparison video here that show noise levels and performance form a small generator of this kind. I reckon that would be a lot less costly and keep the weight low in the boat for sailing or indeed wallowing around at anchor! BUT where do you store the petrol?
But I digress 🙂
So this is a collection of information that I have stored to help me navigate through this rapidly developing area of technology – solar power.
Solar panels are big and it is a puzzle trying to locate them so that feet and ropes don't get tangled up and also so that extra windage does not adversely affect the performance of your boat. Also, lets face it solar panels are pretty ugly. We all have preferences about the look of our boats, and so the aesthetic I’ll leave to you.
I personally don't like the idea of leaving flexible panels on the coach roof to walk over, or having a massive arch on the back of the boat with further windage cause by large solar panels held aloft. What's the point of creating a sail plan for storm conditions and then sticking a big flat metal thing up in the air on the stern of your boat where it can catch more air than you storm sail and affect the steering and heeling angle adversely!
The main thing I wanted to collect here is the issue to do with choosing panels for their technical characteristics, performance and issues about installation rather than aesthetics.
Shade issues are the bane of solar panel location. Shade one panel that has been wired in series and they all throttle back some by as much as 50%. You should wire in parallel. See this video of the impact of the shade of a hand across a panel mounted on a boat.
Here are some voltage drop calculators that will be useful for your sizing and location planning:
- Solar Guppy – Download a spreadsheet
- No Outage .com voltage drop calculator online
- Electrician .com voltage drop calculator online
- Elec toolbox .com wire size calculator online
There is a very good forum here too….happy researching 🙂
Clearly I am undecided …watch this space to see what I finally do….:-)