What to ask for in fitout?

[WotEver]

 

HAY what are you doing posting this time of night???!!

 

Errr.....

I had a bad dream. I got up. I made coffee. I played on here

[MtB]

I had a bad dream. I got up. I made coffee. I played on here

 

 

And I was awake at that time because feckkin Network Rail were running a generator for lighting here with a faulty governor, and driving a sheet of piling in at the rate of one every twenty minutes all night, about 30 yards from my bote...

[cuthound]

Eh? What sort of unit is THAT supposed to be for a generator??!!!

 

Anyway the discussion veered off on this tack when mross said them £4k 12v batteries can be charged at 500A. I said the gear to charge 12V at 500A would cost about £10k. No-one has come up with a more accurate figure yet.

 

 

 

 

 

I'm pretty certain the OP stated this fairly early in the thread when 650AH/day was first questioned. He said he used 24v as motorhomes in Oz use 24v almost universally. CBA to trawl back and find it though...

Sorry, spurious h.

 

I was tired after driving to Surrey and back to do some DIY on my youngest sons flat.

 

I'll amend my original post.

[magictime]

I'm pretty certain the OP stated this fairly early in the thread when 650AH/day was first questioned. He said he used 24v as motorhomes in Oz use 24v almost universally. CBA to trawl back and find it though...

 

No, it was 12V living on motorhomes he mentioned:

 

I've done quite a lot of 12V living - caravan in Europe and over here our motorhome quite a bit out bush, so 'learnt' what is needed

 

However even 1000watt to provide 300ah per day at 12v could only really be done on the best summer days but it will provide the majority or near enough all during summer, but use of the genny will be needed for around 9 months of the year.

 

As I said, the "rule of thumb" I had in mind was that a solar panel typically generates the equivalent of 4-5 hours' full power at its rated output on a summer's day in the UK, which would suggest that 300Ah is pretty conservative. If they managed (much more optimistically!) to generate 400Ah on an average day in the three summer months, 200Ah in the six spring and autumn months, and 100Ah in the three winter months, yes, you'd need the generator around nine months of the year, but for six of those months you'd "only" need to run it every 3 days.

 

Now maybe that's more often than the OP would like, so fair enough, I can see why he might want to have more than 600Ah of battery capacity, but 1200Ah just seemed a lot as a starting point given that he's talking about a solar array designed to replace a good proportion of the energy he uses on a daily basis for a good proportion of the year.

 

As I say, it just seems to me that there's a bit of a clash between two approaches going on here: one in which you use a generator for a long time once a week to recharge a large battery bank which then runs down towards 50% capacity over the next 7 days, and one in which you have a solar array large enough to replace all or most of the power you use on a daily basis for most of the year.

[MtB]

 

No, it was 12V living on motorhomes he mentioned:

 

 

Ok thanks for checking. *Something* in the thread left me with the impression that the OP was planning a 24v system though. No idea what.

 

 

 

 

As I say, it just seems to me that there's a bit of a clash between two approaches going on here: one in which you use a generator for a long time once a week to recharge a large battery bank which then runs down towards 50% capacity over the next 7 days, and one in which you have a solar array large enough to replace all or most of the power you use on a daily basis for most of the year.

 

 

I see no clash. Surely if the OP wants a system that works 52 weeks of the year, it needs designing to cope with the three winter months when solar generation is negligible. Designing one that only works for most of the year isn't good enough.

[Alan de Enfield]

 

No, it was 12V living on motorhomes he mentioned:

 

 

 

As I said, the "rule of thumb" I had in mind was that a solar panel typically generates the equivalent of 4-5 hours' full power at its rated output on a summer's day in the UK, which would suggest that 300Ah is pretty conservative. If they managed (much more optimistically!) to generate 400Ah on an average day in the three summer months, 200Ah in the six spring and autumn months, and 100Ah in the three winter months, yes, you'd need the generator around nine months of the year, but for six of those months you'd "only" need to run it every 3 days.

 

 

Interesting - my 'rule of thumb' is slightly different but (whilst being a lot more pessimistic for Winter) gives similar results in Summer.

My formula assumes 50% efficiency of the panels, but operating for twice the period of your 'system' If we take Summer 'daylight' to be from 04:00 to 22:00 (18 hours) then I am also assuming that I only get 55% 'effective' light on the panels.

 

Summer time - I work on 50% of theoretical output for 10 hours per day at an average of 13,5v

Winter time - I work on 50% of theoretical output for 1 hour per day at an average of 13.5v.

 

So with 1000 watts :

Summer - Theoretical output 74A, x50% = 37A, for 10 hours per day = 370Ah

Winter - Theoretical output 74A, x50% = 37A for 1 hour = 37Ah

[Robbo]

 

Interesting - my 'rule of thumb' is slightly different but (whilst being a lot more pessimistic for Winter) gives similar results in Summer.

My formula assumes 50% efficiency of the panels, but operating for twice the period of your 'system' If we take Summer 'daylight' to be from 04:00 to 22:00 (18 hours) then I am also assuming that I only get 55% 'effective' light on the panels.

 

Summer time - I work on 50% of theoretical output for 10 hours per day at an average of 13,5v

Winter time - I work on 50% of theoretical output for 1 hour per day at an average of 13.5v.

 

So with 1000 watts :

Summer - Theoretical output 74A, x50% = 37A, for 10 hours per day = 370Ah

Winter - Theoretical output 74A, x50% = 37A for 1 hour = 37Ah

Do those figures tend to be accurate as well in the real world or on the conservative or optimistic side, as it seems a good formula to go by.

[Alan de Enfield]

Do those figures tend to be accurate as well in the real world or on the conservative or optimistic side, as it seems a good formula to go by.

 

The 'formula' seems to be 'about right' for my installation (170w 'low light' panel, mounted flat, but with the ability to angle slightly if needed to catch the afternoon sun)

 

My Summer' formula gives the same results as 'magictime' but I just arrive at them a different way.

I think for Winter, output is so minimal, and unreliable, that it is almost better to 'write off' solar production and have alternative arrangements capable of meeting 100% of demand

[magictime]

I see no clash. Surely if the OP wants a system that works 52 weeks of the year, it needs designing to cope with the three winter months when solar generation is negligible. Designing one that only works for most of the year isn't good enough.

 

OK, let me put it this way:

 

Suppose somebody wants to design an all-solar power generation system that meets his needs 52 weeks a year. He works out that in the depths of winter, he's going to need a 4kW solar array. So he sticks ten 400W panels along the length of his roof and chugs off into the sunset.

 

Most of us would think this bloke is crackers, because he's paid so much money and given over so much space to a system that is only suited to his needs for a few months of the year, and the rest of the time is complete overkill. For most of the year, he just isn't seeing any benefit from fitting a 4kW array rather than, say, a 2kW array.

 

I'm suggesting that if someone fits a whacking great battery bank and generator fitted to his needs in the depths of winter, it is similarly going to be complete overkill most of the year if he also has a large solar array. For much of the year, he just isn't going to see any significant benefit from fitting a "run-generator-once-a-week" system rather than a "run-generator-every-three-days" system.

[Robbo]

 

OK, let me put it this way:

 

Suppose somebody wants to design an all-solar power generation system that meets his needs 52 weeks a year. He works out that in the depths of winter, he's going to need a 4kW solar array. So he sticks ten 400W panels along the length of his roof and chugs off into the sunset.

 

Most of us would think this bloke is crackers, because he's paid so much money and given over so much space to a system that is only suited to his needs for a few months of the year, and the rest of the time is complete overkill. For most of the year, he just isn't seeing any benefit from fitting a 4kW array rather than, say, a 2kW array.

 

I'm suggesting that if someone fits a whacking great battery bank and generator fitted to his needs in the depths of winter, it is similarly going to be complete overkill most of the year if he also has a large solar array. For much of the year, he just isn't going to see any significant benefit from fitting a "run-generator-once-a-week" system rather than a "run-generator-every-three-days" system.

The oversize bank can reduce the generator running by averaging out the solar days, so in non summer and non winter time you may have enough sun on average over the course of a week (or how big your bank can cover) for you daily needs.

[ditchcrawler]

 

 

Ok thanks for checking. *Something* in the thread left me with the impression that the OP was planning a 24v system though. No idea what.

 

 

 

 

Probably from the suggestion that high power installations work better at a higher voltage.

[magictime]

The oversize bank can reduce the generator running by averaging out the solar days, so in non summer and non winter time you may have enough sun on average over the course of a week (or how big your bank can cover) for you daily needs.

 

OK, fair point. Still, you only "need" that extra capacity to the extent that (1) you don't expect to make up any day-to-day shortfall from the solar panels just by cruising, and (2) you aren't willing or able to make up any shortfall from the solar panels and cruising combined by running the engine or a generator as needed on a day-to-day basis.

[Robbo]

 

OK, fair point. Still, you only "need" that extra capacity to the extent that (1) you don't expect to make up any day-to-day shortfall from the solar panels just by cruising, and (2) you aren't willing or able to make up any shortfall from the solar panels and cruising combined by running the engine or a generator as needed on a day-to-day basis.

 

That's correct but you can replace solar with cruising, batteries are only the buffer. If you regularly cruise but only at weekends, that cruising may generate all the electric you need for the week but only if you have somewhere to store it.

[magictime]

 

That's correct but you can replace solar with cruising, batteries are only the buffer. If you regularly cruise but only at weekends, that cruising may generate all the electric you need for the week but only if you have somewhere to store it.

 

Sure. But even with a pretty modest battery bank, you might reasonably expect that having fully recharged it through cruising once a week, a decent solar array would generate enough power on a day-to-day basis to ensure that it never fell below 50% capacity for maybe six months of the year. The question then becomes, during the other six months (or whatever), am I willing and able to 'top up' from day to day as needed using my engine or generator, or would I rather invest the money and space in a battery bank large enough that I don't need to worry about it?

[Robbo]

 

Sure. But even with a pretty modest battery bank, you might reasonably expect that having fully recharged it through cruising once a week, a decent solar array would generate enough power on a day-to-day basis to ensure that it never fell below 50% capacity for maybe six months of the year. The question then becomes, during the other six months (or whatever), am I willing and able to 'top up' from day to day as needed using my engine or generator, or would I rather invest the money and space in a battery bank large enough that I don't need to worry about it?

If you only plan for a few days grace in charging then that will be only now, those batteries will reduce capacity over time. A larger bank will potentially reduce less as you may not be taking as much out of them percentage wise.

[magictime]

If you only plan for a few days grace in charging then that will be only now, those batteries will reduce capacity over time. A larger bank will potentially reduce less as you may not be taking as much out of them percentage wise.

 

Well, at this point I think you've successfully persuaded me that there's a strong case for allowing a bit of headroom over and above the 600Ah I originally suggested as a starting point! Still not sure 1200Ah isn't overkill, though, in an actively cruising boat with a large solar array; it still seems like a lot of money and space to invest in something that arguably wouldn't be earning its keep for such a large chunk of the year.

[Robbo]

 

Well, at this point I think you've successfully persuaded me that there's a strong case for allowing a bit of headroom over and above the 600Ah I originally suggested as a starting point! Still not sure 1200Ah isn't overkill, though, in an actively cruising boat with a large solar array; it still seems like a lot of money and space to invest in something that arguably wouldn't be earning its keep for such a large chunk of the year.

Of course having a oversize bank for the majority of boaters would be not worthwhile, it only really benefits those that liveaboard all year round and are off-grid for that time. For someone who's on shore power regularly and cruises daily at other times then a "undersized" bank may be more appropriate.

[IanD]

Wouldn't something like the Hybrid Marine "Power Station" meet the OPs requirements?

 

http://www.hybrid-marine.co.uk/

 

48V system, 5.5kW charging from engine, added solar as needed, 48V 200/400Ah Odyssey or 800Ah 2V traction cells, aimed at gas-free boats with heavy electrical use which seems to be what is wanted. Usable battery capacity (to 50%) with traction cells would be 20kWh -- cells weigh about a ton but that's just free ballast in a new boat.

 

Heavily sound insulate the engine bay and add a hospital silencer and it would probably be as quiet as a cocooned generator, also cheaper and much more reliable.

[Robbo]

Wouldn't something like the Hybrid Marine "Power Station" meet the OPs requirements?

 

http://www.hybrid-marine.co.uk/

 

48V system, 5.5kW charging from engine, added solar as needed, 48V 200/400Ah Odyssey or 800Ah 2V traction cells, aimed at gas-free boats with heavy electrical use which seems to be what is wanted. Usable battery capacity (to 50%) with traction cells would be 20kWh -- cells weigh about a ton but that's just free ballast in a new boat.

 

Heavily sound insulate the engine bay and add a hospital silencer and it would probably be as quiet as a cocooned generator, also cheaper and much more reliable.

It does make sense for the OP to look at electric propulsion as well. However for me the power plant would be a 13kw genny and electric propulsion.

[JJPHG]

Wouldn't something like the Hybrid Marine "Power Station" meet the OPs requirements?

 

http://www.hybrid-marine.co.uk/

 

48V system, 5.5kW charging from engine, added solar as needed, 48V 200/400Ah Odyssey or 800Ah 2V traction cells, aimed at gas-free boats with heavy electrical use which seems to be what is wanted. Usable battery capacity (to 50%) with traction cells would be 20kWh -- cells weigh about a ton but that's just free ballast in a new boat.

 

Heavily sound insulate the engine bay and add a hospital silencer and it would probably be as quiet as a cocooned generator, also cheaper and much more reliable.

Interesting!

[mross]

Hybrid = cruise in silence - run engine for 2 or 3 hours when tied up in the evening - seems pointless, unless you go on mains every night.

Edited January 31, 2017 by mross

[Robbo]

Hybrid = cruise in silence - run engine for 2 or 3 hours when tied up in the evening - seems pointless, unless you go on mains every night.

Hybrid; run engine when cruising, use electric when locking.

 

Other benefits are that you don't need as big an engine as both systems can provide power. A smaller engine is more efficient at the usual canal speeds we do.

Edited January 31, 2017 by Robbo

[mross]

Hybrid; run engine when cruising, use electric when locking.

 

Other benefits are that you don't need as big an engine as both systems can provide power. A smaller engine is more efficient at the usual canal speeds we do.

Do you have a hybrid? Does it have advantages or would you get a conventional boat next time?

[Robbo]

Do you have a hybrid? Does it have advantages or would you get a conventional boat next time?

Depends on the boat, if it had narrowboat with a nice engine room I would have a something like a Gardner to suit.

 

On my current boat (lets say the engine needed replacing) I would do like Tjalk Sara did and have something like a 13kw genny and electric propulsion, but I would need to look at both methods more in depth to see what the cons and benefits are with the different methods.

Do you have a hybrid? Does it have advantages or would you get a conventional boat next time?

Although my other boat has sails and a diesel engine, so that's a hybrid right ?

[IanD]

The system I posted about ("power station") isn't a hybrid, it's a high-power 48V brushless generator and big battery bank/high-power inverter added onto a conventional diesel engine, for people who want more electrical power (5.5kW generation at 1250rpm) than you can realistically support with a travelpower or alternators -- target market is gas-free boats.

 

It's part-way to a parallel hybrid (which they also offer) but with less added cost and complexity -- obviously you can't travel on electric power, but that's not the intention. Parallel hybrids save some fuel but not as much as you'd expect because the losses in going generator -- controller -- battery charge -- battery discharge -- controller -- electric motor largely cancel out the fuel saving from running the diesel for shorter periods at higher load factor. They do have the advantage of silent travel/locking, but the difference compared to a properly silenced (soundproofed engine room + hospital silencer) diesel isn't worth it for most people.

 

Series hybrids (diesel generator + electric-only drive) are invariably more expensive, less reliable and less fuel-efficient than parallel ones, as several trials and investigations have shown -- in many cases such boats have been converted back to diesel.

Edited January 31, 2017 by IanD