How much is too much Solar Power and how much is just enough?

[ditchcrawler]

3 minutes ago, LadyG said:

I am not sure about @ditchcrawler s statement saying any charger will work if left 'on' long enough (though I want to be charged up overnight), my researches indicate that the charger, and nowadays they are nearly all 'smart', needs to be inputing lots of electrickery in order to 'excite' the battery electrons. Rule of thumb being about twelve percent of the capacity of the battery bank. 

So how do you account for your 2 solar panels charging your battery with an output of 40- 40 amps, you said you only have 2. and in spring time probably quite a bit less.

 

[Tony Brooks]

3 minutes ago, LadyG said:

I am not sure about @ditchcrawler s statement saying any charger will work if left 'on' long enough (though I want to be charged up overnight), my researches indicate that the charger, and nowadays they are nearly all 'smart', needs to be inputing lots of electrickery in order to 'excite' the battery electrons. Rule of thumb being about twelve percent of the capacity of the battery bank. 

 

As long as the charger VOLTAGE is sufficient to overcome the resistance of the electrolyte current will flow and given time the conversion of the lead sulphate to lead oxide will take place. As a typical float charge is around 13.6 volts and absorption charging voltage will be in excess of 14 volts the chemical conversion will take place so Brain is correct any flowing charging current will convert the chemicals it is just a question of how long fully charging takes. In fact a long low current charge is likely to produce a higher charge than  a fast short one.

 

[LadyG]

45 minutes ago, ditchcrawler said:

So how do you account for your 2 solar panels charging your battery with an output of 40- 40 amps, you said you only have 2. and in spring time probably quite a bit less.

 

Fair enough, I think my usage in winter is only about 30 to 40 ah.

The engine is the main, and often the only charger in winter.

Batteries are very healthy in summer. Alternator plus solar input.

Just now, ie  today,  the Webasto is running occasionally to heat the boat, the sun is shining, the controller shows solar generating 34.5volts at 5.0 amps. In theory five hours of sun will input 25 ah?  However ......... batteries won't be 'accepting' the maximum available. They will be topped up again tomorrow morning by running the engine, once they are drawing less than 5 amps maybe 60 to 90 minutes, longer if they have been down more than usual.

Update: the sun has now gone in to sulk mode, and it is also snowing.

Solar will effectively be trickle charging, I accept that, but it won't be anything like enough in winter. I was thinking about shoreline chargers which will be much smarter than my Epever controller.

Edited February 10, 2021 by LadyG

[Tony Brooks]

3 minutes ago, LadyG said:

Fair enough, I think my usage in winter is only about 30 to 40 ah.

The engine is the main, and often the only charger in winter.

Batteries are very healthy in summer. Alternator plus solar input.

Just now, ie  today,  the Webasto is running occasionally to heat the boat, the sun is shining, the controller shows solar generating 34.5volts at 5.0 amps. In theory five hours of sun will input 25 ah?  However ......... batteries won't be 'accepting' the maximum available. They will be topped up again tomorrow morning.

Solar will effectively be trickle charging, I accept that, but it won't be anything like enough in winter. I was thinking about shoreline chargers which will be much smarter than my Epever controller.

 

If the 5 amps is for the battery side of the controller then that is what the batteries will be accepting. If its for the panel side then I agree with you but I think most controllers show the actual charging current flowing to the batteries. The panel current is pretty much relevant.

[doratheexplorer]

I've 525w of solar.  From mid-Feb to Beginning of November, I can get enough power to get by on, if it's a good day. From April to September I don't need to run my engine for electric at all.  During those shoulder seasons the weather makes a lot of difference, heavy cloud and mooring under trees or tall buildings is a problem, I'll get some but I'll likely need to top up.

 

It's possible to tilt my panels but it's a faff, but that's something to consider.

 

I reckon if I put another 200w of solar on my boat, I'd probably get another 10-20 days a year where I currently run my genny/engine, but wouldn't need to.  Is that worth it?  For me, probably not.  If I run my engine 3 hours a day, I'm probably using less than £2 of petrol from my genny, over 15 days, that's £30 at the most.  If I put another 200w solar panel on my roof, I'd need to replace my charge controller, buying cheap, the panel might be £50, the charge controller £200, plus about £20 for extra cables, connectors etc.  So £270 to save £30.  So it would pay for itself in 9 years.  But in that time, I would have less space to store things on the roof (important for liveaboards).  At the moment, my 3 x 175w panels, plus chimney, plus pole, hook & plank, leaves me enough space to squeeze 15-20 bags of coal on the roof, so I'd need a much better reason to add to my solar.  In other words, there's a sweet spot where the law of diminishing returns makes it unreasonable to add more panels.  This will vary from boat to boat, but for me, it's about 500w.

Edited February 10, 2021 by doratheexplorer

[Porcupine]

Thanks very much - really helpful. 

[doratheexplorer]

This is where I got my solar stuff.  Popular with lots of boaters, and they're used to delivering to the canal.

 

https://www.bimblesolar.com/

[Porcupine]

?

[tehmarks]

16 hours ago, David Mack said:

House-type panels around 1.6-1.8m long by 0.9-1.0m wide...fit conveniently on a narrow boat roof.

 

But often not easily if you plan to use the roof to get to the other end of the boat, which I personally think is essential as a single-hander.

[LadyG]

3 hours ago, markeymark said:

My only advice is that a fridge (high energy consumer) is superfluous when its cold. I have a rat-proof metal box on the foredeck with cheese, milk etc. in so cut the fridge out for 4-5 months of the year. In the summer when there is often too much solar then I use the fridge.

Buy filtered milk, eg Cravendale in litre bottles, they will last for three weeks, just open one at a time and don't drink out the bottle. I keep them in cold store, along with white wine and beer, also meat in mouse proof containers. Set  'little nipper' if your cat brings Apodemus Sylvaticus on board, you can tell by the stramash at the cat flap, once on board, cat loses interest.

[Trevor Lyons]

A firm in Stafford, Loryan Micro Renewables, has been recommended to me. They provide a number of packages, ranging from a single panel (335W) t0 8 panels (2680W). Their contact details are below.

 

Friends of mine, a couple in Longport, are converting a 70' butty into an electric powered narrowboat. They are living aboard during the conversion,  They have 2.4kW of solar panels and they say that even though it is winter, they have all the power they need from the panels.

 

Their boat is kept warm with a woodturner and a coal fired cooking stove. They have disposed of a large diesel generator that was aboard, and plan to get a much smaller top-up petrol unit.

Edited February 10, 2021 by Trevor Lyons
typo

[LadyG]

Petrol. NO 

[tree monkey]

26 minutes ago, LadyG said:

Petrol. NO 

But it mixes so well with a bit of tonic, ice and a slice

[doratheexplorer]

32 minutes ago, LadyG said:

Petrol. NO 

Petrol.  Yes.

[Mad Harold]

I don't think you can have too much solar.

The amount will be dictated by the amount of available roof space and money.

Like the amount of Guinness you take on your boat trip is dictated by how much of a list your boat can take.

[ditchcrawler]

3 hours ago, tehmarks said:

 

But often not easily if you plan to use the roof to get to the other end of the boat, which I personally think is essential as a single-hander.

We met a boater who had escaped London on the B&F and he had to adjust the panels to get through the bridge holes 

[David Mack]

3 hours ago, tehmarks said:

 

But often not easily if you plan to use the roof to get to the other end of the boat, which I personally think is essential as a single-hander.

Which is why my single panel is offset to one side of the cabin roof.

[Trevor Lyons]

2 hours ago, doratheexplorer said:

Petrol.  Yes.

I met a narrow boater recently who had a petrol generator, fully encased in a plastic casing, so very quiet. It produced around 2.8kW. Not strictly portable, but luggable, and could be kept in a bow compartment.  Of course, one must be careful with petrol aboard, but provided it's outside the cabin, it should not become a danger. By contrast, gas is the real peril once it sinks into the bilges. (My boat has no gas, having a diesel Kabola space heater  and diesel heating, with oven hob & microwave all electric). Diesel generators are nice, but expensive and often bigger than there is room for.

 

I've fitted 4 x 300W panels, i.2KW in all, plus a 500W wind generator that I have yet to install. The latter is a Renytek unit that has its own controller within it and which outputs 12v DC current that can be connected to the battery bank with no further additions. 

Edited February 10, 2021 by Trevor Lyons
Add text

[Alan de Enfield]

1 minute ago, Trevor Lyons said:

By contrast, gas is the real peril once it sinks into the bilges.

 

As do petrol fumes.

A petrol generator should NEVER be run on board, not only for the possibility of petrol fumes trickling into the bilges, but CO building up and then you 'wake up dead'.

 

Petrol generates many times more CO than either gas or diesel.

[Trevor Lyons]

1 minute ago, Alan de Enfield said:

 

As do petrol fumes. A petrol generator should NEVER be run on board, not only for the possibility of petrol fumes trickling into the bilges, but CO building up and then you 'wake up dead'. Petrol generates many times more CO than either gas or diesel.

Indeed! (The petrol genny I saw the other day was being run on the towpath, but its owner planned to install it with a flexible exhaust hose leading outside via a thru-hull fitting).

[Alan de Enfield]

Just now, Trevor Lyons said:

Indeed! (The petrol genny I saw the other day was being run on the towpath, but its owner planned to install it with a flexible exhaust hose leading outside via a thru-hull fitting).

 

 

O'dear. PLEASE don't do it ........................................

 

A Gas-Safe engineer did just that and killed his wife and child.

Those generators are not designed to have modified exhausts, or for pemanent installation inside a boat - maybe if you see him again you could point this Inquiry out to him,

 

 

MAIB Report No 02/2015 - Arniston - Very Serious Marine Casualty (publishing.service.gov.uk)

 

On Monday 1 April 2013, the emergency services attended the motor cruiser Arniston on Windermere, Cumbria, where a mother and her daughter had been found unconscious. The two females were taken by air ambulance to Lancaster Royal Infirmary where they were pronounced deceased. A postmortem concluded that the cause of death was carbon monoxide poisoning. The subsequent MAIB investigation identified that:

• The carbon monoxide poisoning had resulted from the inhalation of fumes emitted from a portable generator installed in the boat’s engine bay.

• The external exhaust system fitted to the portable generator had been modified to incorporate a silencer that had become detached from both the generator and the outlet pipe to the vessel’s side.

• The portable generator’s engine exhaust fumes filled the engine bay and spread through gaps in an internal bulkhead into the aft cabin where the mother and daughter were asleep.

• The portable generator was not intended by its manufacturer to be installed into an enclosed space, nor was it intended to be modified in any way.

• The improvised exhaust system attached to the generator was constructed from materials and using methods that were not appropriate for this application.

• The boat’s occupants were not alerted to the danger because two carbon monoxide sensors fitted to the boat at build were out of date and had been disconnected from the power supply

 

ARNISTON’S OWNER Arniston’s owner was 39 years old. After leaving school he completed a heating and ventilation apprenticeship, during which he gained City and Guilds qualifications in pipe-fitting and welding. He was also on the ‘Gas Safe Register’4 , which is the official gas registration for the United Kingdom. In 2007, the owner started a business installing and servicing heating and ventilation systems in commercial premises.

 

 

[Trevor Lyons]

4 minutes ago, Alan de Enfield said:

 

Those generators are not designed to have modified exhausts, or for pemanent installation inside a boat - maybe if you see him again you could point this out to him,

 

OK, I'll do that if he's still there, moored at Westport Lake, Burslem. Thanks!

[tehmarks]

1 hour ago, David Mack said:

Which is why my single panel is offset to one side of the cabin roof.

 I did that on the last boat with a panel mounted towards the stern end, but there wasn't more than a person's-foot width between the edge of the panel and the handrail if it didn't overlap the handrail on the other side. It definitely made my life a bit awkward.

 

I've gone for flexible panels on this boat for that reason, though I might augment them with some rigid panels when I have the funds and the inclination. Mainly because rigid panels are so cheap in comparison, and in comparison to even five years ago.

[Mad Harold]

1 hour ago, Trevor Lyons said:

Indeed! (The petrol genny I saw the other day was being run on the towpath, but its owner planned to install it with a flexible exhaust hose leading outside via a thru-hull fitting).

There's a bit more required than a thru the hull exhaust.

To comply with BSS regs,the fuel tank must be vented to outside the hull,and have a drain,again to outside of the hull,to drain any spillage caused by refuelling.It also needs to be secured in place.

[roland elsdon]

Going back to the initial question the answer will probably be n+1. Where n is the number of panels you already have.

While this may not be helpful I do have a sort of solution.

we have 2 roof fitted solar panels. Plus 2 folding panels that can run on fly leads into the mppt regulator. If we are not boating for a couple of days we add this extra 300 w of panels into the system. We have very limited cabin top but 35 feet of cargo deck to put these add on panels on. Works well.