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Ace of Spades

Favouring Solar when on Shore Line

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Hi All

 

First post here so go easy on me!!  

 

We are early on in our journey that will hopefully see us eventually take to the water and I am trying to research as many things as possible.

This great forum and other searches has been able to answer most of my questions so far, but there is one question that I am struggling with is as follows:

 

If you have a good solar array (well good in summer at least!!) is there a way for the on board electrical system to favour this over power from a shore line when hooked up?

I.e. it will use electricity generated from solar before pulling additional power needs from the shore line.

From what I can find out, it seems solar will charge your batteries and therefore power 12v items, but any 230V needs will simply pass through the charger/inverter and power sockets directly.

 

As a bit of background - we eventually want to set up a boat that fits our expected cruising pattern.  Basically I envisage being marina based (unfortunately we both still need to work so CC'ing is simply not an option) however we most certainly want to get out and about, so will probably take the boat out in the local area over a weekend to moor for a week and commute from there before returning to the marina (plus holidays etc!!).  Living and working in the Stoke-on-Trent area means we have lots of lovely canal options within easy commute, but could not move enough to legitimately CC.  Therefore our desire for lots of solar to help with power needs when away from the Marina.  However it seems such a waste to not use this energy when on a shore line.

 

I did find a topic that kind of touched this, but didn't really answer the question, and was from something like 12 years ago so I suspect things have moved on somewhat since.

 

Hoping someone more knowledgable can help.

 

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If you are in the marina and not on board you don't need to have your 'hook-up' connected and just let the solar charge the batteries.

What 230v stuff would you want to have 'switched on', on board when you are not there ?

 

If you are living on board then use the solar all day to charge the batteries and run the inverter etc etc., If your voltage starts to drop, put the 'mains hook-up' on overnight to charge the batteries, if you don't need to top the batteries up, then don't switch the 'hook-up' on.

 

Its all about 'managing' your batteries (and lifestyle). Boating does require some human input, you can automate a lot of 'stuff' but that leaves more to go wrong and removes some of the 'fun' of boating.

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You can set up the output voltage of the battery charger to be lower than the Solar controller output so that the solar output will always override the battery charger.

Some inverters have a 'power assist' knob and will take a preset amount from the 'mains hook-up' and then top up from the batteries, I don't know if you can set this to 'zero', but you then have to remember to re-adjust it upwards to prioritise the 'mains hook-up' when you need to.

 

It gets complicated and relies on 'operator memory'

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Timer on battery charger, turn off at 0800 turn on at 8.00 pm, mains stuff draws off shore 12v off batts. Overide as needed.

overthinking leads to complexity, complexity leads to confusion, comfusion leads to breakdowns , breakdown leads to engineers , engineers lead to $$$$$$, and other engineers.

We have a stupid split charge relay on our camper here. I have a solar charger on the start battery and a solar panel on the domestic. One  on windscreen one rear doors. On a sunny morning the volts on the engine rise at 13.1 the stupid relay clicks on and puts the power through to the rear battery, that drops the volts and opens the switch. 5 mins later the volts rise again and the process restarts over and over.

why did the engineer not wire the relay through the ignition?.

cos thats hard work. Eventually the solenoid will go and themnill chuck a switch in. 

Till then every morning click click click.

dont say park up west east tried that.....

 

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If you have a Combi inverter charger then as you say, mains will pass trhough it when on shore power and the charger part will be active. As to which “wins” between solar and Combi, as said it depends on the set voltage and or current limit. Most Combis have multiple settings and you could for instance turn the charge current down to zero. This would mean the batteries were never charged by the Combi. Or you could lower the voltage on the Combi charger so that when it is sunny, the sokar “wins”. But of course when it’s not sunny the charger will “win”. The latter is probably the better solution although I suppose it depends on how much solar you have vs your power usage. If the solar can easily supply all your power, might as well have the Combi outputting zero current. But in winter you would need to turn it up again as it’s virtually impossible to have all your power needs met by solar in winter.

 

Probably the best thing is to ensure you can easily change the setting s on the Combi - a PC interface or other control panel is ideal. A Combi on its own without any controlling device connected can be a fiddle to adjust and even then, you are often quite limited as to what you can change with the internal switches.

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16 minutes ago, Alan de Enfield said:

If you are in the marina and not on board you don't need to have your 'hook-up' connected and just let the solar charge the batteries.

What 230v stuff would you want to have 'switched on', on board when you are not there ?

 

If you are living on board then use the solar all day to charge the batteries and run the inverter etc etc., If your voltage starts to drop, put the 'mains hook-up' on overnight to charge the batteries, if you don't need to top the batteries up, then don't switch the 'hook-up' on.

 

Its all about 'managing' your batteries (and lifestyle). Boating does require some human input, you can automate a lot of 'stuff' but that leaves more to go wrong and removes some of the 'fun' of boating.

Many thanks for the replies.  I suppose there was a degree of naïvety in wondering if there was a way of automating the process - but I have no problem with human input - as you say, its what its all about!!

Just to clarify, we will be living aboard.

15 minutes ago, Alan de Enfield said:

You can set up the output voltage of the battery charger to be lower than the Solar controller output so that the solar output will always override the battery charger.

Some inverters have a 'power assist' knob and will take a preset amount from the 'mains hook-up' and then top up from the batteries, I don't know if you can set this to 'zero', but you then have to remember to re-adjust it upwards to prioritise the 'mains hook-up' when you need to.

 

It gets complicated and relies on 'operator memory'

Probably another silly question but I can see how setting the voltage of the charger lower than then solar controller would prioritise the solar to charge the batteries, and would I assume then switch shore power when voltage on the solar drops off, but out of interest what would happen if the power draw was greater than the solar was producing?  Would this cause a switch to shore power in this set up?

That said, probably just turning the shore line on and off as necessary is probably the best answer.  I assume it would be possible to have some form of internal "master switch" to save actually having the physically disconnect the line.  (Please don't laugh if that's a standard fitting!!)

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1 minute ago, Ace of Spades said:

That said, probably just turning the shore line on and off as necessary is probably the best answer.  I assume it would be possible to have some form of internal "master switch" to save actually having the physically disconnect the line.  (Please don't laugh if that's a standard fitting!!)

Most chargers have an on/off switch. 

 

Just sayin’...

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Old 'mainframe computer' mantra, the KISS principle - Keep It Simple, Stupid.

 

If you're marina based, electricity is inexpensive / affordable - so solar wont add any value

If you're genuinely cruising, then  the engine (with a sensible alternator charging system) will charge your batteries.

If you are CCing or on a mooring without 'leccy - then some solar is a good idea.

 

 

 

 

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10 minutes ago, OldGoat said:

Old 'mainframe computer' mantra, the KISS principle - Keep It Simple, Stupid.

 

If you're marina based, electricity is inexpensive / affordable - so solar wont add any value

If you're genuinely cruising, then  the engine (with a sensible alternator charging system) will charge your batteries.

If you are CCing or on a mooring without 'leccy - then some solar is a good idea.

 

 

 

 

Yeah a good philosophy to be honest and one that SWMBO is always telling me I ignore too much!!

 

7 minutes ago, Paringa said:

In winter I don't see you getting enough solar to make this worth worrying about.

Unfortunately as we will both still be working we won’t have the luxury of be able to cruise all summer long so although we won’t be permanently tied up in a marina and will be out as much as possible, as I said probably finding somewhere to moor for a week locally and commuting, some periods of marina living in the summer will be inevitable. Obviously we can’t stay out for weeks on end as we couldn’t probably move far enough without falling foul of CRT ( and of course I also have no desire to become an inconsiderate continuous moorer ) so will have to return to the marina.

Edited by Ace of Spades

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31 minutes ago, Paringa said:

In winter I don't see you getting enough solar to make this worth worrying about.

He is right.  If you have 1000 watts of solar on the roof in December and January that will give you about 100 watts for 4-5 hours on average, so half a unit of electricity from the bollard or less than 10p per day. In summer June July you should get over 800 watts for 8 hours so about 6.5 units per day.  On a dull day in winter I get about 10 amp hours from 600 watts, or a few minutes of engine running to charge the batteries.

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The answer to the question is that the batteries will almost do it automatically as long a s your aim is optimum battery charge.

 

Any charging source has its output rated in watts and that    = Amps X Volts. With discharged batteries the Amps will be high and if they are at a level tat would equate to more Watts than the charging device can supply the charging voltage is automatically depressed until the Amps X the Volts = the  source's   maximum Wattage. When the batteries demand less current then as the Amps fall the voltage will rise.

 

Now, if you have two charging sources the same applies. If the current (Amps) being drawn from each source is high enough the charging voltage from each source will be depressed and both will operate at their maximum output. As the batteries charge they demand less and less current so the voltage from both sources starts to rise UNTIL it reaches the regulated voltage for one source (as it is unlikely that both sources will have exactly the same regulated voltage). At that point that one source starts regulating its output but the other one keeps on charging with a depressed voltage. As the batteries become more and more charged the current falls and the voltage still rises until it reaches the regulated voltage of the second source then that two starts regulating the voltage. Now any "problem" but it is not really a problem is that once one source starts regulating it might totally shut down but that will make little difference to the overall charging performance because if it did shut down and the second source could not supply enough current the voltage would again be depressed so the first source will stop regulating and start charging.

 

If you want to go messing with the regulated voltages then you will be able to influence which source MIGHT shut down first but given the cost of shoreline electricity I would suggest it is simply not worth it just to save the cost of running the mains charger while delivering no output. As more than one person said KISS.  In any case as soon as you turn a 12V load on any source that has shut down will probably start up again because the load has depressed the voltage.

 

The main thing that might upset the above is where a mains charger decides to go into float too early but even that is not a problem because teh mains charger wuld have been working in the earlier part of h day and leaving teh solar to do the long low current charge needed to fully charge the batteries for the bulk of the day.

 

 

 

 

 

 

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1 hour ago, Ace of Spades said:

Hi All

 

First post here so go easy on me!!  

 

We are early on in our journey that will hopefully see us eventually take to the water and I am trying to research as many things as possible.

This great forum and other searches has been able to answer most of my questions so far, but there is one question that I am struggling with is as follows:

 

If you have a good solar array (well good in summer at least!!) is there a way for the on board electrical system to favour this over power from a shore line when hooked up?

I.e. it will use electricity generated from solar before pulling additional power needs from the shore line.

From what I can find out, it seems solar will charge your batteries and therefore power 12v items, but any 230V needs will simply pass through the charger/inverter and power sockets directly.

 

As a bit of background - we eventually want to set up a boat that fits our expected cruising pattern.  Basically I envisage being marina based (unfortunately we both still need to work so CC'ing is simply not an option) however we most certainly want to get out and about, so will probably take the boat out in the local area over a weekend to moor for a week and commute from there before returning to the marina (plus holidays etc!!).  Living and working in the Stoke-on-Trent area means we have lots of lovely canal options within easy commute, but could not move enough to legitimately CC.  Therefore our desire for lots of solar to help with power needs when away from the Marina.  However it seems such a waste to not use this energy when on a shore line.

 

I did find a topic that kind of touched this, but didn't really answer the question, and was from something like 12 years ago so I suspect things have moved on somewhat since.

 

Hoping someone more knowledgable can help.

 

In fairness solar is a good " help " when out and about on a sunny summers day but in reality plugged in to mains is so damn cheap any way you will probably only save about fifty pence a day messing about switching over. Even now here in winter using plenty much leccy for washing machine, fridge, freezer, kettle, telly etc etc etc etc etc etc etc we are only using 1.36 per day on hook up and in the grand scheme of things boating being more expensive than living in a house fifty p a day is the square root of diddly squat.

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Given that you are in the planning stage (you've not said whether you will be having a boat built) here are some -not often aired - thoughts, though I will get attacked for them. You're enquiring about electrics - so I'll limit comments to that -

  • Battery voltage - 24V equipment, pumps, inverters, alternators; et all -for me at least - have proven to be much more reliable than 12v
  • Battery types. Not fashionable but NiFe batteries are pretty well nigh unburstable, can be left in any state of charge etc etc - BUT are bulky and heavy
  • Refrigeration. a 'proper' fridge freezer is preferable to a fridge with a 'conservator' area in the top of it. Liebherr do a nice efficient one.
  • If you're having a boat built or doing major renovations to an existing vessel, it might be a good idea to fit a waterproof plug and socket on the roof (I have a pigeon box and various sockets horizontal (so they don't get flooded) in the end(s).  

 

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Tony Brooks many thanks for taking the time to write a very good explaination that really did help.

in fact many thanks to everyone.

1 hour ago, OldGoat said:

Given that you are in the planning stage (you've not said whether you will be having a boat built) here are some -not often aired - thoughts, though I will get attacked for them. You're enquiring about electrics - so I'll limit comments to that -

  • Battery voltage - 24V equipment, pumps, inverters, alternators; et all -for me at least - have proven to be much more reliable than 12v
  • Battery types. Not fashionable but NiFe batteries are pretty well nigh unburstable, can be left in any state of charge etc etc - BUT are bulky and heavy
  • Refrigeration. a 'proper' fridge freezer is preferable to a fridge with a 'conservator' area in the top of it. Liebherr do a nice efficient one.
  • If you're having a boat built or doing major renovations to an existing vessel, it might be a good idea to fit a waterproof plug and socket on the roof (I have a pigeon box and various sockets horizontal (so they don't get flooded) in the end(s).  

 

I will research NiFe batteries, don’t know anything about them.

Outside sockets sounds like a brilliant idea, probably wouldn’t have thought of that. Will add that to the list, thank you.

 

We are I would say still very much at information gathering stage, and are weighing up whether to have a boat built or buy a used boat,  either way we would probably be doing major works.

 

Sure this won’t be my last question and I’m really looking forward to sharing my journey.

 

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If you haven't owned a boat before then my recommendation would be to buy a used boat and live with it for a while.

There are many pitfalls in designing the inside of a boat and once you have lived on one you will know what works or doesn't work for your lifestyle. Then you should be able to design the boat and get it right for you.

 

ETA I have a reasonable amount of solar (400w) but never bother with it when on our moorings as its to much faff, i just leave the charger to get on with its job.

Edited by Loddon

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