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


Porcupine

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Hi -  me and my partner are taking the plunge and preparing live aboard our boat. How much solar power will we need. We work from the boat so we use laptops every day. We watch TV but only on our IPad (so need to keep it charged) we use mobiles, chargeable headphones, Kindle (no toaster, no big TV, no kettle). What would you recommend? And what make of panel? Ta muchly. 

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The basic rule with solar is this. No matter how many panels you put on the boat you will never generate enough power in the winter in the UK. So you’ll need a plan B for winter.

 

A few hundred watts and a decent battery bank should be fine for most of the rest of the year.

Edited by booke23
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26 minutes ago, Porcupine said:

Hi -  me and my partner are taking the plunge and preparing live aboard our boat. How much solar power will we need. We work from the boat so we use laptops every day. We watch TV but only on our IPad (so need to keep it charged) we use mobiles, chargeable headphones, Kindle (no toaster, no big TV, no kettle). What would you recommend? And what make of panel? Ta muchly. 

 

Roughly October to March you cannot get enough Solar on a Narrow Boat to do anything, its output wll be next to negligible, so work out how you are going to live with no solar in the Winter and then anything it produces in the Summer will be a bonus.

 

500 watts should give an average user sufficient output for 3 or 4 main Summer months BUT only you can determine what you will need .

 

You need to do a proper power audit of your usage (everything and for how long per day it will be in use, as a working from home liveaboard your demands will be very different to a non-working liveaboard or even a non liveaboard).

 

When you have done your audit, come back with the figures and we can convert that to how you need to replace it.

 

Will you be in a marina with electric hook-up ?

Will you be continuous cruising in London with high rise buildings alongside the canal (very little direct sunligh and loads of shadows)

Will you be CCing in the country side with trees giving shadows ?

 

You will need to run a generator / to run the engine / or plug into a landline most days to replace what you have used.

 

Edited to reaarange randome leturs appearaing

Edited by Alan de Enfield
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I have 550 watts, flat panels, ie not tilted.

I have nominal 600 amp hour batteries, in good condition.

I have a Webasto.

A laptop and a tablet and a phone.

I use the engine, maybe one hour per day to charge my batteries from November to March, and that is exceptional 'cos I can't move, due to lockdown and other stuff.

If your comms are essential, use something like a Poyntin or top of the range WiFi Router with antennae.

and buy candles (joking), but you have to conserve energy in winter. Go to bed early and get up late.

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52 minutes ago, LadyG said:

I have 550 watts, flat panels, ie not tilted.

I have nominal 600 amp hour batteries, in good condition.

I have a Webasto.

A laptop and a tablet and a phone.

I use the engine, maybe one hour per day to charge my batteries from November to March, and that is exceptional 'cos I can't move, due to lockdown and other stuff.

If your comms are essential, use something like a Poyntin or top of the range WiFi Router with antennae.

and buy candles (joking), but you have to conserve energy in winter. Go to bed early and get up late.

 

I don't think the one hour a day is good advice, especially in winter with little solar input.  It is generally accepted that with lead acid batteries on a typical boat with typical use (electric fridge) you need four hours a day and 8 to 10 hours once a week.

 

I suspect your huge batter capacity is hiding a fair degree of sulphation from you, especially if you are frugal with your electrical use but time will tell.

 

To the OP, for a narrowboat I would suggest as much solar a syou can afford that will fit on the boat. The more you have the shorter the "winter" with insufficient output.

Edited by Tony Brooks
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1 hour ago, Porcupine said:

Thanks, very helpful. What kind of solar panels wound you recommend? 

Solar panels are much of a muchness unless you want to pay a lot more for the high end technology which might produce something like 20% higher output than standard panels. Have a look at someone like https://www.bimblesolar.com/solar to see what is available. House-type panels around 1.6-1.8m long by 0.9-1.0m wide are usually cheapest per watt of output , and fit conveniently on a narrow boat roof.

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Panels and LiPO4 batteries are fairly cheap now, esp. if you have the wherewithal to build a system yourself - I did mine a year or so ago - 1100 watts of panels (4); 50A solar charge controller; 100A BMS; 3000W 24V Inverter; 24V 8cell LiPO4 battery 100Ah; 25A battery charger and 1.6 KVA generator - all told cost around £3000. Most of it off ebay ex China I imagine.

 

The best part was doing all the research and sourcing - matching the power requirements and then assembling. The day it started up \i was super impressed with my efforts. The great thing about the LiPO4 battery is that you can bang in as much charge as you like - The limit is really how big a battery charger you can find.  The BMS takes care of the charging regime too.

 

I usually charge an hour each day on generator in the winter. In summer you can give the neighbours power...

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I I have 4.6kws of solar, it is a widebeam and has an electric motor for driving it  I find in winter even 4.6kw isn't enough solar! I have LifePo4s and their tolerance to being left under charged without damage is great. LAs can't cope with the abuse that LifePo4s can, but if you go that way, please do lots of reading beforehand.

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I've had solar for 7 years.  The answer is normally 'more'. 

 

Do your power audit - Bimble, as mentioned above, have a downloadable spreadsheet to assist.  I use about 1kWh/day in summer, reduced to 400Wh in winter by turning my fridge off. 

 

I have 4 x 320w panels (two in use during summer, and all four in winter).  I aim to park with a view of the sun.  The panels are laid flat on the roof in boxes, but can be tilted up to 45deg if necessary (and it is) to catch the rays. 

 

In essence, winter input is about 1/10 that of summer, so cut out unecessary usage (ie the fridge) and have a large enough battery bank to see you through the days of insufficient sun.  In winter this could mean up to two weeks, which is unobtainable - so go for the largest bank that you can recharge, using your alternator, in a full day of engine running (say eight hours); if you're using lead-acid and a 70-100A alternator then this means you're limited to about 800Ah of batteries (of which only about 400Ah is usable), if you're prepared for the expense and nerdiness of  LiFePO4, then again 800-1000Ah of batteries would max out the alternator, but 700-800Ah is usable.  But if you actually do this, make sure that your engine is quiet or be prepared to either live out in the countryside or invest in large quantities of alcohol to placate your neighbours with....

 

Boats are not houses - electricity is an expensive luxury.  The first rule is to minimise your usage.  The second rule is that generating it is ten times more expensive than the grid, the third rule is that storing it is like water in leaky buckets and the forth rule is that wind is even more fickle than sunshine.

 

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Just now, churchward said:

The US Senate has voted 56-44 in favour of the trial and it being constitutional.  6 Republicans voted for the trial with Democrats.  11 more will need to be convinced of guilt to convict at the end so still not looking likely.

 

I watched a good deal of the presentation and debate from both sides.  Impeachment House Managers (the prosecution if you will) presentation was very good and well argued but as one has come to expect the Trump lawyers etc. did quite a poor and unconvincing job.

 

Donald Trump impeachment trial is constitutional, Senators say in vote (usatoday.com)

 

 

Former President Donald Trump’s attorney David Schoen said he would “have to do better next time” after several Republican senators criticized Monday’s presentation by Trump’s legal team, with one calling them “disorganized” and some praising the case made by Democratic impeachment managers.

Trump attorney David Schoen said he thought the House managers “did a good job” and acknowledged the criticisms made by some, including Sen. Bill Cassidy, R-La., that their arguments didn’t stick.

No, no,no.  That's Hot Air - a completely different (and usually on a different planet) method of (em)powering stuff.

 

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4 minutes ago, churchward said:

The US Senate has voted 56-44 in favour of the trial and it being constitutional.  6 Republicans voted for the trial with Democrats.  11 more will need to be convinced of guilt to convict (if they all turn up to vote) at the end so still not looking likely.

 

I watched a good deal of the presentation and debate from both sides.  Impeachment House Managers (the prosecution if you will) presentation was very good and well argued but as one has come to expect the Trump lawyers etc. did quite a poor and unconvincing job.

 

Donald Trump impeachment trial is constitutional, Senators say in vote (usatoday.com)

 

 

Former President Donald Trump’s attorney David Schoen said he would “have to do better next time” after several Republican senators criticized Monday’s presentation by Trump’s legal team, with one calling them “disorganized” and some praising the case made by Democratic impeachment managers.

Trump attorney David Schoen said he thought the House managers “did a good job” and acknowledged the criticisms made by some, including Sen. Bill Cassidy, R-La., that their arguments didn’t stick.

 

Think you've strayed a bit, Churchward

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5 hours ago, Tony Brooks said:

 

I don't think the one hour a day is good advice, especially in winter with little solar input.  It is generally accepted that with lead acid batteries on a typical boat with typical use (electric fridge) you need four hours a day and 8 to 10 hours once a week.

 

I suspect your huge batter capacity is hiding a fair degree of sulphation from you, especially if you are frugal with your electrical use but time will tell.

 

To the OP, for a narrowboat I would suggest as much solar a syou can afford that will fit on the boat. The more you have the shorter the "winter" with insufficient output

 

Yes, it's not a recommendation, I'm just broadbrushing, in fact what I do is to run engine every two days or even sometimes three days (assuming I'm getting some solar charging) to make use of the big battery banks, once I had to run it for seven hours to get batteries back to parity, I don't want to do that very often

I monitor charging progress as best I can by judging by the draw in amps with engine running,  and the voltage gauges, not ideal, I would much rather have a proper Battery Monitor, but I have two domestic battery banks, so that would require two monitors, There is always a compromise, with two domestic banks, I spread the payments for purchasing batteries.   

My newest batteries are the best I could find at the time, deep cycle I believe, though not Trojans. Agm, as I want everything low maintenance /idiot proof.

I only have a 70amp alternator, not ideal, but it is what it is. 

If weather is dull for a long period, I will compensate by longer engine run,  in normal times, I would be moving the boat, and maybe charge up overnight in a marina two or three times  per winter month. I understand I need an 80amp charger for a 600 ah domestic battery bank 

Fridge is only 'on' when solar input will charge it.

The stove is main source of heating, Webasto usage is minimised, as it uses power, and using more power means running the engine longer.

I take my laundry to the launderette, and I do washing up and showering etc when the engine is running, not sure if that makes much diffference, to battery usage,  but it might :)

To be honest, I don't want more than two big panels, for both practical and aesthetic reasons, I had a frame already on the boat

Edited by LadyG
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As one who has yet to sort out solar panels I'm following this thread with interest. My master plan is to CC during the warmer half of the year and cower in a marina during the cold bits.

 

Mentioning cold reminds me that LiFePO4 cells don't like the cold so are generally installed within the boat rather than in the engine bay. Perhaps users of them could confirm/deny this point. 

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8 hours ago, LadyG said:

I would much rather have a proper Battery Monitor, but I have two domestic battery banks, so that would require two monitors, There is always a compromise, with two domestic banks, I spread the payments for purchasing batteries.   

 

Is this true? If the two battery banks are linked then you may only need the one monitor.

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11 minutes ago, Col_T said:

 

Is this true? If the two battery banks are linked then you may only need the one monitor.

 

It is true because they are only linked by the negatives when there is no charge (or should be). However, the engine battery spends most of its life fully charged in most cases so does not really need monitoring.

 

@LadyG Implies she has an ammeter and voltmeter so as long as they are accurate enough those plus a bit of knowledge/technique provides adequate battery monitoring as long as they are connected to the domestic bank.  This is far less likely to encourage the boater to destroy their batteries by telling lies about the state of charge.

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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.

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9 hours ago, LadyG said:

 

If weather is dull for a long period, I will compensate by longer engine run,  in normal times, I would be moving the boat, and maybe charge up overnight in a marina two or three times  per winter month. I understand I need an 80amp charger for a 600 ah domestic battery bank 

 

Any size charger will charge them, how long it takes is another matter. You probably are not getting much above 45 Amps from your alternator unless your batteries are very low. ou only need to monitor your charge voltage and current to tell when the batteries are charged, much more accurate than any battery management meter.

1 hour ago, Idle Days said:

As one who has yet to sort out solar panels I'm following this thread with interest. My master plan is to CC during the warmer half of the year and cower in a marina during the cold bits.

 

Mentioning cold reminds me that LiFePO4 cells don't like the cold so are generally installed within the boat rather than in the engine bay. Perhaps users of them could confirm/deny this point. 

Some have heat pads to warm them before charging

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39 minutes ago, Tony Brooks said:

 

It is true because they are only linked by the negatives when there is no charge (or should be). However, the engine battery spends most of its life fully charged in most cases so does not really need monitoring.

 

@LadyG Implies she has an ammeter and voltmeter so as long as they are accurate enough those plus a bit of knowledge/technique provides adequate battery monitoring as long as they are connected to the domestic bank.  This is far less likely to encourage the boater to destroy their batteries by telling lies about the state of charge.

Sorry @Tony Brooks , I have three battery banks, my starter battery (bank) is 80ah, and new 2000), it looks after itself , re-charging quickly after engine start up.. There are three newish (2019), agm s in one bank, and two big agm s of unknown type or age, they cope with water pump and charging small electronics, they will be changed when they die, maybe with two small 6 volt Trojans. I don't know the science, but I've always liked to have batteries in different banks with different characteristics.

Time will tell, I expect my main Domestic Bank to last for eight years, worse case scenario five years. I may have shortened their life due to this winter's charging regime, but running the engine not under load , as is happening at the moment, will cost money in engine fuel, and servicing, and maybe shorten engine life, I hope not.

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14 minutes ago, LadyG said:

Sorry @Tony Brooks , I have three battery banks, my starter battery (bank) is 80ah, and new 2000), it looks after itself , re-charging quickly after engine start up.. It is left 'off' when not 'starting'.

There are three newish (2019), agm s in one bank, and two big agm s of unknown type or age which cope with water pump and charging small electronics, they will be changed when they die, maybe with two small 6 volt Trojans. I don't know the science, but I've always liked to have batteries in different banks with different characteristics.

Time will tell, I expect my main Domestic Bank to last for eight years, worse case scenario five years. I may have shortened their life due to this winter's charging regime, but running the engine not under load , as is happening at the moment, will cost money in engine fuel, and servicing, and maybe shorten engine life, I hope not.

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 minimum. Smart chargers can revive, / re-condition batteries to a greater or lesser degree.

Edited by LadyG
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