What wattage of solar panels should you try for as a liveaboard.

Nostrodamus

Nostrodamus

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When you are sailing in the sun and anchoring off as much as possible power aboard becomes a real issue.
We need to fit new solar panels this year and obviously the more the better.
Given the choice we would tow Chernobyl behind us to meet our power requirements but we have to be realistic.
What wattage of solar panels is realistic for meeting the average liveaboards lifestyle?
 
I used to have a 60 watt panel on an arch, it was okay but after anchoring for 3 days or more the batteries needed the engine running to top them up. Then got 2 x 100 watt panels, had more than enough from April to October, but it may be different in the winter. We did have a keel cooled fridge which helped, we also had LED's, but we did watch downloaded material on the tv and had two computers going a lot.
 
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I have 200wts but we managed with 150wts this year after one panel failed. We did a lot of motoring (in the Med) mind you and we're pretty frugal, but the fridge is on all day and watching DVDs in the eve is no problem. No radar, but occ HF radio, can transmit without running engine now. I now have an additional180Ah big Varta for windlass/radio/DVD, separate from a parallel pair of 125Ah Rolls batts for engine/self steering/fridge. The split system evolved rather than being planned, two panels connected to each bank. And there is a connecting VSR for when engine running. Bog standard Yanmar alternator seems fine.
 
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Short answer - as much as you can fit.

Longer answer - do you first know roughly what your daily usage is in amps ? Good, now you have a target to meet and can work out whether its feasible to meet it with the real estate you have available. If you cant meet it you can either run a regime where you start to minimise use or work out how to make up the shortfall.

Got to go, I'll add a bit more later
 
At the moment we can manage about 3 days at anchor before the batteries get down to 12.2v but we did get new batteries and increased the bank last year. After 3 days we have to use the generator (portable).
We have the usual fridge, computers and music running a lot so the consumption is quiet high.
The panels we did have were the semi flexible stick down ones which I would advise against. These failed after 2.5 years and the company (GB Sol) refused to help.
We would like a stern arch making this year where we could mount the solar panels but I am trying to find out roughly how many watts i really need to fit.
Certainly some of the liveaboards here suggest 3 to 400 watts to be self sufficient totally and not to have to worry about power requirements.
 
We have 40w which is just about sufficient to keep the light in the regulator display going. Once the wind is up our Rutland 913 pushes out 3-10amps but that's about 20 hours a week so pretty pointless to compared to 60ah on the engine alt... If I could do it again I would install 200w ish but position is more important than capacity I suspect. Even a bit of shade cuts out most of the output so placement under boom etc is a waste of excess capacity.
 
I think the ambition to be completely self sufficient with (expensive) panels is unnecessary since we all already have engine alternators and/or generators.
Running the engine or generator every three or four days at anchor is hardly onerous. In practice we rarely stay in one place for longer than three days anyway.
Last time was off Cadiz and well worth it, a great place.
 
We are pretty much self sufficient for power with 125 watts. We can anchor indefinitely with the fridge running 24/7 at the height of summer, although we are fairly frugal so far as entertainment is concerned, mostly reading with LEDs and charging the iPad. Where we struggle is if we are in a port for a few days, in a fixed position with the shadow of the radar scanner or other masts across the panels. Now in September the reducing hours of daylight are beginning to have an effect. So ideally for us a little more would be good, maybe 200 watts, but I would struggle to fit the extra. As said, half an hour under engine usually sorts it.
 
We have 200w on a stern arch with an MPPT controller. We're fairly moderate power users so it's adequate most of the time. As Vyv says the problem is if moored on a quay bows south /stern north- the shading means the solar panels give very little in this situation. Rigid solar panels are relatively cheap so If starting again I'd go for nearer 300w. Make sure you have a suitably rated MPPT controller!
 
Over the past 16 months in the sun, discounting wind and towed generation, I've found 130W to be adequate at anchor where the main drain on power is from the Frigomatic keel cooled fridge. I set the thermostat half way day and night. During the long sunny days there's an excess of power generated and I can make water, use the HF radio, charge the vacuum cleaner and other rechargeable devices. My old batteries lose up to 25% of their charge during the hours of darkness.

On the other hand, discounting wind and towed generation, 130W doesn't cut it for me whilst sailing unless I use the Hydrovane steering or I switch off some of the instruments. To be frank, the chart plotters consume so much power so I sometimes revert to a hand held GPS.

Ideally I would like more solar power: about 300W total would suit my purposes.

Not asked for in your question I know but I do have a wind generator that will produce up to up to 35A every hour of the day and night in the right winds (it haven't experienced the right winds yet) but more realistically up to 7A in some tradewind anchorages and usually less than 7A when tradewind sailing. My towed generator produces about 1A per knot when sailing.

Friends on a 40ft catamaran have over 1kW of solar power and have sufficient battery capacity to do all their cooking on an induction stove and in a microwave oven!
 
Going back to where I was, we use around 100-120a/day; laptops, instruments/GPS while out at anchor and fridge (50-60a/day) are the main users. I installed 200w (4x50) of rigid solar panels about a month ago. Deliberately choosing 4 panels to help deal with shading as there inevitably is some even though they are on a sort of arch at the stern. I'm trying the various connection schemas, at the moment its a toss up between all parallel and 2+2 series/parallel. All parallel is delivering 50-60 amps a day (in Greece), series was giving 10-15a less. This measurement is somewhat subjective as some days are overcast and other days we move and the engine goes on for a bit which skews things.

I try to keep the house batteries above 75% capacity so overall the need to run the engine has reduced significantly. I have a large house bank, 700a, which helps with this regime. Combining a large house bank with a capable inverter helps cope with the few 240v needs that crop up without resorting to shore power.

I have an MPPT controller but I'm not convinced I need it, given I'm keeping the batteries fairly well charged anyway & that parallel connection seems to be more efficient. Certainly I understand that MPPT works best with matched panels so building a system with disparate panels is probably better with PWM. Either way, having a controller that allows data collection and setpoint tweaking enables me to see whats going on on a daily basis and change the preset values to match my system. I also read recently that tweaking the setpoints to bring the bulk/absorb voltage and timings down when leaving the boat for extended periods is a reasonable alternative to covering the solar panels to prevent battery overcharging.
 
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Full time liveaboard in the Carib. 400 watts of tiltable solar, Blue Sky MPPT controller. 675 am/hr battery bank. My fridge makes ice.

When the sun shines I am fully charged by mid day. The extra capacity is great when we have a succession of cloudy days as the bank stays above 30% which is the point at which I start the engine. I think I have had to do this 3 times in the last 6 years.

I could scrape by on a sunny day with 200 watts being diligent about following the sun.
 
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350w in total running a fridge and freezer 24-7 plus laptops and charging various bits and bobs, with 2 x 260 amp Rolls bats for domestic use, then a 4.5 Gen for the watermaker and hot water and any other high powered stuff. We have not been in port since May for power or water reasons.
 
I fit quite a few solar panels to liveaboard narrowboats in the uk. I fit domestic panels as they work out cheapest/watt. I think in the med I would want mono crystalline and these are usually what my customers want because they are the "best'" apparently. I recommend amorphous ones for the uk though...they are space inefficient and rubbish in comparison with monos in the summer sun but perhaps 10-15% better when it is grey and horrible.

250 watts is enough for low power users (no/rare TV, 12v fridge, led lighting) up to about 400 Ah battery bank) 500 watts copes well with heavier users for 9 months a year (240v fridge, hair dryer every morning, 2 computers (600-800 Ah bank). For those that expect to recharge even in mid winter, I double the solar array and if possible, fit a 200w dc immersion heater to make the most of the additional capacity in summer.

I would really appreciate photos of solar arches, especially of those with large arrays/domestic panels as I've not yet worked out how!
 
We survived the summer on 300w (2x150w) on a radar arch running the fridge/freezer 24/7, inverter for the kettle, toaster and occasional induction hob. I have another 300w to fit when I can get around to it which SHOULD keep us going through the winter (although we will 'cheat' with shore power...). Got a good deal and advice on the panels from Quentin at Turbotricity in Eire (no connection etc...)
 
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