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Solar power

Hi I am nearing the end of my 60Ft boat build, and now my attention turns to the need for power. We have decided to have a generator fitted to give us 230v when on the move ,but most people seem to have solar panels fitted are these a good option and if so which ones are the best and what wattage should we go for it will be a live aboard thanks Tom

Asked by: Tom Grocott  | 5.38pm, Monday 10 October

WW says:

If you just want to keep the batteries topped up when not using the boat, then around 10'to 20W per 100Ah of battery capacity will do. For more substantial input, especially to give useable power, then 200W is probably the minimum. For meaningful power in winter, you may need more panels. You need to do an energy audit really to work out ideal amounts. There is will be an article soon in WW looking at sizing and installing solar systems.
Monocrystaline panels are most efficient, and those that can be fixed in frames clear of the deck (to keep cool- panels lose efficiency as there temperature rises) - and if angled to face the sun, they will be more efficient. However this can be ungainly especially for cruising. fitting flexible monocrystaline panels to the steel roof with adhesive like Sikaflex may be more aesthetically pleasing, though with a drop
In economy.
PWM (pulse width modulation) controllers are cost-effective but MPPT (maximum power point tracking) units may give better performance. MPPT controllers have the advantage that, if you wire two 12V panels in series to give 24V, the charger will step it down to voltages suitable for 12V systems, but should shadows (or lines) cross the panels and the voltage drops (which it can do substantially) then the panel voltage will always be above battery voltage and so be able to charge.
If you want to be self-sufficient, fit as many panels as you can, with decent controller, suitably thick wiring and appropriate fusing. A specialist can be useful- but may be worth fitting after you have had the boat for a while and now how much power you use. If the builder fits the wiring (or at least conduit) - and one or more deck gland fittings for the cabling then you can easily add them in the future- and the price keeps dropping!

Mark Langley  | 11.36PM, Monday 10 October

Apologies for the typos!

Mark Langley  | 11.38PM, Monday 10 October

Readers say:

My husband and I live aboard in Canada and have for 6 years. The past 2 we have been completely independant of shore power. We have solar panels and find if an effective way to generate power in the summer but more challenging in the cloudy winter months. You need a very good battery system if you want to get the most from your panels and if there are lots of cloudy days you will need a generator to keep your batteries topped up if you are independant of shore power for extended periods. You need to know how much wattage you will use from all your electrical appliances to really know how many panels and deep cycle batteries you require.

Shelly L Broeckx  | 5.05PM, Tuesday 18 October

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