Solar Panels

[Matthew P]

Has anyone any, ahem, current solar panel experience?

I have a Garmin 555S chart plotter with fish finder that seems to draw about 1 Amp.  It is connected to a Yahusa lead-acid 7Amp/Hr batteries with two back-ups each of which lasts about a day, i.e I have 3 days power supply.

Given normal UK summer conditions what size panel do I need to trickle charge at least one 7A/hr in a 12 hour day? 

What is the difference between mono crystalline, micro crystalline and other types of panel? Which is most suitable?

I plan to site the solar panel using velcro on the afterdeck of my BR20, so a semi-flexible type is best for installation - or is it?

What is the practical difference between PWM, MPPT and shunting controller?  Is it essential to have an expensive one if the panel is big enough?

Any advice appreciated

Matthew
BR20 Gladys

[jonno]

Matthew's technical questions nicely illustrate the complexities of the electricity onboard issue. While someone is answering him, could they address a slightly broader question for me please? What setup - of battery, solar panel, regulator(?), anything else (?) - would they recommend? The flexible panel idea sounds attractive to me as I'm a bit funny about drilling holes in Ella.

Thanks

John

[IanEagland]

Hi

In good conditions in the middle of summer a 25watt panel will give you about 7 amp hours of charge.

However shading and the fact that your panel will not be pointing directly at the sun means you probably need something bigger. Also on cloudy days you will get much lower output. I think a 50 watt panel would be the minimum I would fit. You can always go bigger, the charge controller will take care of any excess and you will be surprised how little you get on cloudy days. Are you charging the stand by batteries or the battery connected to a the chart plotter? If connecting a battery to anything consuming electricity you should get a charge controller with a low voltage dropout (LDO or LVR) which protects your battery from over discharging. You also need to get a charge controller that can be set to match the type of battery you have, Lead Acid or Gel. You won't go wrong with Steca charge controllers but they are expensive. I have had one in use for 5 years (not on a boat) and it is still working perfectly. I have had an Ebay controller that did not last a year.
Size your charge controller according to the Amps produced by your panel. Calculate the Amps produced by dividing the panel wattage by 16.5.
For a 50 watt panel and lead acid battery I would use a Steca Solsum 5.0F and for a 100 watt panel a Solsum 8.0F. If you need LDO it would be the Solsum 6.6F for 50 watt or 8.8F for 100 watt. These are oversize but it is always better to be over the top rather than working on the limit. The only thing I should mention is that I have never used these in a marine environment. If you cannot keep the controller dry you might need to look at sealed controllers and I have no experience of those.

As to the type of panel there is a good comparison here:-

http://blog.renvu.com/choose-your-solar-technology-monocrystalline-vs-polycrystalline/

In answer to Jonno's question I personally would always go for a maintenance free non spill AGM battery on a boat for every thing other than a starter battery. You will need to make sure the charge controller is suitable for AGM batteries.

PS

You will need to check your batteries charge rate to make sure it can accept the charge from the controller. I only just realised your battery is 7 amp hour. I misread it as 70 amp hours and I have no experience of such small batteries. The battery charge rate may be the controlling factor determining both charge controller and PV wattage.

[Graham W]

For the price of a decent-sized solar panel and efficient MPPT controller, you could buy yourself a really good lithium battery, which weight for weight lasts far longer than its lead equivalent.

I have a long thin Aurinco Bluewater 25 watt solar panel (laid along the top of the boom) with a Genasun MPPT controller, which I use to keep my Tracer 24Ah lithium battery topped up when I'm away from the mains for long periods. However, I think Aurinco may be on the way out, as their panels hardly seem to have dropped in price at all these past few years, while their competition (including those sold by Aurinco's own UK agents Kuranda) seem to be substantially cheaper for a better product.

But back to lithium - a 24Ah battery should last you around five days of heavy GPS use without the need to recharge.  In Corfu with its brilliant sunshine and with the solar panel put in place to catch the early morning sun when the boat is tucked up for the night , I can last three weeks away from the mains.  I think the UK may not be quite so impressive!

[IanEagland]

Hi

Further to my previous post I remembered I have used a Morningstar SunGuard on a camper van and that is a fully potted sealed unit good for PV panels up to a maximum of 60 watts.If the panel is flat mounted and not pointing at the sun you could probably go to up 75 watts. Should be OK in a marine environment. £ 24.29 plus vat and carriage here:-

http://www.windandsun.co.uk/products/Solar-Charge-Controllers-/Morningstar-Charge-Controllers#.VyzHOfkrKUk

[Matthew P]

Thanks Ian and Graham

Graham's big battery solution is probably the most robust and simple although the investment is off-putting and I like to think I might need power for more than 5 days although this is probably wishful thinking.   In any case someone gave me a nice couple of 7Ah VRLA (Valve Regulated Lead Acid apparently) batteries when he bought himself a fancy Lithium 24Ah one .

I had ambitious ideas of linking two of the Yuasa 7Ah batteries in parallel and connecting them through my cheapie Ebay controller to the GPS and solar panel.  But I am nervous of connecting batteries with marginal voltage differences engaging in secret and debilitating electrical Sumo wrestling with each other, the controller and the GPS.  I'm not about to start messing with diodes to try and prevent complicated back currents and stuff so now I am simply connecting the batteries one at a time with good quality weather proof plugs and sockets to the controller, and hence the solar panels, for charging or connecting direct to the GPS.  This means I have to physically disconnect and reconnect to swap batteries from charging to GPS supply but at least I know what is going on.

I think the best place to mount solar panels on a Bayraider is the after deck but space is limited so the maximum size I can fit is two 20W panels in parallel on either side of the mizzen.  I think this makes sense because at least one panel will not be in the mizzens shade.  I am using semi-flexible panels and mounting them with hefty 50mm wide velcro (£5 from Screwfix but black or £mega from B&Q in white) to the deck so they can be removed when not on tour and, like Jonno I don't like making unnecessary holes.

Maybe unwisely I've ordered a pair of "20w Semi Flexible Light Weight Sunpower Solar Panels"  from Ebay that are not only the cheapest at £30 each but also claim to be the most efficient at 23%. Probably fall apart - I'll let you know.

Ian's advice on controllers is useful and chastening - I expect I'll need to replace mine but as I've already mounted it in an IP65 box I'll give it a go.

Total cost so far, given a little help from my friend with his surplus batteries is about £100 and ? happy hours faffing at my workbench.

All good fun and I'll keep my fire extinguisher handy.

Matthew
BR20 Gladys       

[IanEagland]

Hi Matthew,

I was going to suggest that parallel connection might be the way to go. If you charge all the batteries on a mains charger just before making the connections everything will be fine.  Any minor voltage difference will quickly stabilize. You are only doing what you do when you jump start a car!.

If really worried put a 5 amp fuse in the plus connection between the batteries. I was going to add that you should fuse the supply anyway and that should be as close to the batteries as possible.You could fit fuses to every battery and only join the supplies after the fuses, that would give you  good protection. If you are in doubt as to what I mean let me know and I will do a wiring diagram.

Another thing to consider is the wire you use. It should really be marine rated with tin plated strands. I also now use crimp barrel connectors to join wires on boats and shrink wrap the join with glue lined shrink wrap. I leave enough length to allow for cutting out the connector several times in case I need to modify wiring.

[Matthew P]

Thanks for the advice Ian.  I've wired two batteries in parallel as you suggest with no fires, fumes or explosions yet.  Your wire connection tips are useful too.  I'm leaving the third battery unconnected but ready to plug in as a reserve.

The two 20W  solar panels appear to be working well. I'm not sure how salt water resistant they are, I may need to seal the edges of the laminate and stuff the junction boxes with Vaseline.

Live system testing at Ullswater next weekend.

Matthew
BR20 Gladys

[jonno]

Graham, Ian and Matthew

Thanks for this.  I like the simplicity of Graham's advice.

John

[Tony]

Hi, Jonno.
If it's simplicity you like, how about something like this?

Plastimo Echofish 400.
Runs on 4x AAA batteries.
Digital and graphic display. (Black & white, so batteries last)
Fish alarm
Depth alarm
Transducer can be fixed (best option) or used with yellow float for use off a pontoon. (Fairly pointless)

Disadvantages
Small screen  ( really needs to be within arms reach)
Loose wire a trip hazard
Transducer causes drag when fixed tho the hull. (It is just possible to mount it on the inside of some hulls - signal detected through 9mm ply - but designed to fix to the transom. )
Weed v hard bottom not well distinguished 

Would be more useful when creek crawling if it could be mounted forward facing. Otherwise, gives an accurate depth reading with a loud alarm for shoaling water - handy in some circumstances.

[Matthew P]

I like the simplicity of the Echofish Tony, I had not realised it was so simple.  Almost as simple as a bamboo stick!  Is the screen readable in strong sunlight?

With a GRP hull, fitting to operate through-hull on the Bayraider should be be possible. 

Just to complicate it, could it be linked to a tablet computer with Navionics GPS?

Matthew
BR20 Gladys

[Tony]

 Yes, Matthew. The Echofish IS as simple as bamboo stick. ... excepting the need for AAA cells, of course . It's only advantage is that it keeps working while you steer!
Easily visible in sunlight but goes weird if you are wearing Polaroid sunglasses.
There is no facility for any conectivity with other gadgets but there is a similar American model ( Sunfish, I think) that has an Nmea output. I bet it "canes" the batteries, though ! 
(See what I did there?  Canes the batteries...? Bamboo stick....? Oh, please yourself....)

Getting back to the point....
The big problem with a solar panel on my boat is where to site it. I need to walk on most of the flat surfaces available and prefer non-slip paint to liquid crystals! Until someone can make photovoltaic sail cloth I've ruled out solar panels
Graham's  Big Lithium Battery solution seems to be the best bet for small boat cruisers, once you accept that you ARE going to run a colourscreen GPS etc. and need megawatts of power on tap all the time. (Expensive but cheaper than using AAA cells !)
As a confirmed cheap-skate, I've been looking at the possibility of using  second hand Makita cordless drill batteries as an easily replaced and re-charged power source for cabin lights and electronics but have found that the usual reason for a Makita drill finding it's way to a car boot sale is that the batteries have had it !
New NiCd 12v 2ah cost about £20, which isn't too bad, I suppose but Li-ion types cost more than double that for a 3ah 18v version, so not really worth the extra electrical fooling about to run your Garmin from it. At 2ah you aren't going  to be running a fridge or a wide screen Navionics chart plotter but it'll give you a glim on a dark night and run an LED anchor light long enough for a summer night.

[Julian Swindell]

I have a simple 20Ahr sealed lead acid battery which I keep charged with a 10W solar panel which is glued to one side of my cabin roof. This certainly lasts all weekend to run a Nasa depth sounder, Garmin 74 GPS and recharge my Android tablet and mobile phone. The only time it ran flat was on a sail back from Yarmouth to poole, when it turned out the battery was on its last legs and needed replacing. It recharges on the mooring and as far as I can judge, if it is sunny, the panel keeps the battery charged indefinitely. I carried out one very unscientific test on one sunny day. I turned everything on and then disconnected the battery. Everything kept on working, just with the solar panel. I haven't felt the need to change the system apart from renewing the battery after three years.

[Andy Dingle]

Similarly to Julien I have two 20w panels on the stern of my BC23 that powers two 50 aph batteries, been running past two years, and sailing thro' two English winters without any noticeable loss in power. Never been charged from the mains in all that time.
I run a dsc/vhf, chartplotter with depth and ais, domestic radio and ipod thingy, nav lights and internal lights etc and soon to be a tiller pilot. Phone and even PC charging.
Touch wood all ok so far.

On a similar them? Has anyone seen these? New to me. That are appearing on boats, primarily aimed at the fishing community..

http://www.ebay.co.uk/itm/like/221877390215?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=122&chn=ps&googleloc=9045997&poi=&campaignid=207297426&device=c&adgroupid=13585920426&rlsatarget=pla-146857555746&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=122

This is just a cheap example, there are many similar types - including bluetooth to your smart phone/tablet. The iBobber (yes, seriously!), for connection to your iphone is another example.
Wont be long before you have your depth, chartplotter, wind etc all just coming into your phone..  no need for all these power problems.. ?

Cheers all - and for those going to Ullswater, have a great time. Would like to go, but it's a bit of a clat taking the BC up there..

Andy

[Michael Rogers]

Good heavens, even fossils like me might be dragged into the technological age with devices like that. Nevertheless, I'm going to request enlightenment for my total ignorance (I'm referring to the fishy transducer widget Andy has linked us up to). Please don't laugh, or at least do it kindly.
What do you actually DO with that yellow thing? Does it have to go overboard? Does it work through the bottom of the boat? Something which is a 'water resistant' design isn't necessarily waterPROOF (cf the scam around wristwatch specs).

End of memakingacompletefoolofmyself.