Inverter Size Compared to Your Boat Size?

[cherod]

Grinder , drill , jigsaw , plane , battery charger ,,, kettle , micro wave , hair dryer , aquavac , usb s ,,, shower , watermaker ( eventually ) . plan is solar , wind and 2 k genny . ? (( would love a TIG welder but i think a genny to run it would be prohibitively large / expensive , ))

 

[KompetentKrew]

A bread maker would be nice but I don't fancy drawing about 50A from my batteries for an hour. I'd probably have to put back about 75A later to keep them charged. OK on shore power.

I measured 550Wh - which would be about 50A from the batteries, if my maths is right - from my Panasonic including the bake cycle.

However, I'm in the habit of using only the dough cycle at the moment, and baking 9 rolls in the oven. I haven't measured what the dough-only cycle uses.

 

[cherod]

Requirements are easy enough to estimate and as others have said it isn't practical to use a battery to heat water for a shower. Calculation is pretty simple if you assume insulation is perfect. It doesn't make a huge difference in practice and just means it will take a few minutes longer than shown by the theoretical figure.

A 1kW element will heat 30 litres from 20°C to 50°C in around 63 minutes or 74 minutes starting from 15°C. Obviously in line with the actual figures quoted by Paul.

I have a 1.2kW element in a 45 litre tank which would take about 79 mins. or 92 mins. starting from 20°C or 15°C. The 1.2kW element actually cuts off at about 65°C but the engine gets it up to a ludicrous temperature (probably 90°C). It certainly keeps warm for a lot longer after an engine run than after heating on shore power.

Def some food for thot in there , i think the tank i built is around 5 or 6 gals so maybe a little genny boost would be required some times !! ?. ty

 

[geem]

I need 240v for my TV, power tools, Fridge Freezer and hairdryer. I use an old 600 watt modified sinewave inverter bought from Maplins, its silent and operates everything without any problems. I resentry bought a "modern" 3000 watts modified sinewave inverter, it is light, compact but noisey and therefore I only use it when I need to. I have 3 x 110 domestic and 1 x 95 engine batteries, charged by 2 x 50 watt solar panels and an old Ampair wind generator. The solar panels do all the work and the wind generator just spins round producing almost nothing which means that this winter it will need an overhaul or disposal.

If it was me I would ditch the wind turbine and add more solar. Wind generators just cant compete with solar for Watts/£. They are noisy, ugly and tend to catch stuff in their blades

 

[vas]

fwiw (nothing...)

220Ah @24V Trojans T105RE
3000VA Victron Multiplus (pure sine) - Victron recommends 400Ah for this inverter/charger
lots of things on 240V mainly tools + watermaker and next season 68lt water tank 1800W element
600W solar
In the med July-Aug, can be at anchor for two weeks (well 1 is realistic then I need to move to empty the black tank with two onboard) just fine, no engine, no generator needed.
thinking of upping solar to 850W so I can run 3/4h per day the 2KW watermaker on batteries now run them for 20mins-30max
typically without watermaker, system is on float by midday, have one dodgy fridge which will be fixed this winter so hopefully consumption will drop substantially
btw, never on shore power not even in port.

V.

 

[RupertW]

Fairly enough. Presumably there is a cross-over point where 12V cables heat the air exactly as much as an inverter plus 240V cables. Thanks.

There must be and I looked at a wire calculator and saw that my 1.5mm 240v cable over 5m for 1.5kw would lose 0.24% of voltage whilst trying to put 12v through it for the same power would lose 89% of voltage. So for AC the only loss I really need to think of is the inverter at 90-95% efficiency. But I had the 240v element, the wiring and switches for it and the inverter already so it was an easy option for me to add in a transformer to step down the voltage and a programmable VSR to ensure the water is only heating when batteries are nearly full and solar can keep up. If I was starting totally from scratch I could consider 12v element with massively thick wires running 5m and a very very powerful charger to keep up when I was on mains but I think I’d still go inverter and mains.

 

[noelex]

We heat almost all our shower water via (electric) solar and battery power for about 2/3 of the year in northern climates.

If using a calorifier (we use a more versatile and slightly more efficient system) it does not make much difference to the overall total power consumed if this is via inverter and 240v AC element or a 12/24v element. However, the lower wattage 12/24 elements make it easier to utilise energy that would otherwise be wasted from the solar panels/wind generator. On the other hand, high wattage AC elements tend to be better suited to those boats regularly running a generator as the water can be more rapidly heated during the generator run time.

Hot showers without running the engine are a luxury rather than a necessity, but especially in colder climates they are a significant improvement especially for boats staying at anchor (so away from marina showers) and not moving every day ( so, ideally, the engine is not run frequently). Systems that achieve this (not necessarily electric), without the noise and complication of a generator are viable on even smaller yachts.

As well as the power needed to heat the water, some consideration also needs to be given to the much higher water consumption that will inevitably occur with the availability of regular hot showers. This is more difficult to manage on smaller yachts and is often the limiting factor preventing the ultimate luxury of long, hot showers. On larger yachts this is often not an issue.

 

[Buck Turgidson]

We heat almost all our shower water via (electric) solar and battery power for about 2/3 of the year in northern climates.

If using a calorifier (we use a more versatile and slightly more efficient system) it does not make much difference to the overall total power consumed if this is via inverter and 240v AC element or a 12/24v element. However, the lower wattage 12/24 elements make it easier to utilise energy that would otherwise be wasted from the solar panels/wind generator. On the other hand, high wattage AC elements tend to be better suited to those boats regularly running a generator as the water can be more rapidly heated during the generator run time.

Hot showers without running the engine are a luxury rather than a necessity, but especially in colder climates they are a significant improvement especially for boats staying at anchor (so away from marina showers) and not moving every day ( so, ideally, the engine is not run frequently). Systems that achieve this (not necessarily electric), without the noise and complication of a generator are viable on even smaller yachts.

As well as the power needed to heat the water, some consideration also needs to be given to the much higher water consumption that will inevitably occur with the availability of regular hot showers. This is more difficult to manage on smaller yachts and is often the limiting factor preventing the ultimate luxury of long, hot showers. On larger yachts this is often not an issue.

where do you get so much power from?

 

[noelex]

where do you get so much power from?

Almost all our electric power comes from solar panels. We also have a large frame high output alternator (over 2kw), but with limited engine run times, its overall contribution is very little (perhaps less than 5%). As we have no generator or wind generator and are almost never in marinas, these are our only two possibilities.

Hot shower water is heated electrically in sunnier climates. Even in more extreme latitudes we can use this for much of year, but in winter we use our Reflex diesel heater. The back up is propane/butane, but this is rarely used.

 

[ip485]

We heat almost all our shower water via (electric) solar and battery power for about 2/3 of the year in northern climates.

If using a calorifier (we use a more versatile and slightly more efficient system) it does not make much difference to the overall total power consumed if this is via inverter and 240v AC element or a 12/24v element. However, the lower wattage 12/24 elements make it easier to utilise energy that would otherwise be wasted from the solar panels/wind generator. On the other hand, high wattage AC elements tend to be better suited to those boats regularly running a generator as the water can be more rapidly heated during the generator run time.

Hot showers without running the engine are a luxury rather than a necessity, but especially in colder climates they are a significant improvement especially for boats staying at anchor (so away from marina showers) and not moving every day ( so, ideally, the engine is not run frequently). Systems that achieve this (not necessarily electric), without the noise and complication of a generator are viable on even smaller yachts.

As well as the power needed to heat the water, some consideration also needs to be given to the much higher water consumption that will inevitably occur with the availability of regular hot showers. This is more difficult to manage on smaller yachts and is often the limiting factor preventing the ultimate luxury of long, hot showers. On larger yachts this is often not an issue.

I know it is a luxury but I like a long hot shower - and I mean hot. I dont know how you can produce hot water in volume without a huge solar array, given the solar will also be looking after the other electrical needs in temperate climates. I tank 1,200 litres which gives time at anchor measured in weeks even with long showers without resort to other sources but that is quite large for most yachts.

 

[Mistroma]

We heat almost all our shower water via (electric) solar and battery power for about 2/3 of the year in northern climates.

You seem to say that most of your water heating is via solar power and that's for 8 months of the year in a northern climate.

I can meet battery charging needs for about 4 months each year in Greece. Output needs to be topped up for a month either side of peak summer using engine or generator. I have very little excess electrical capacity to heat water during this 6 month period. Output drops off a cliff in winter.

I have 300W panels with MPPT regulator and can deploy another 100W panel at beginning and end of season. I do use solar showers to get 5-10 litres for showering and could replace that with more PV. However, using PV to heat water is a lot less efficient than direct heating of a solar shower.

It would be interesting to know:
1) Size of solar array
2) Geographic cruising location (e.g. West coast of Scotland)
3) Size of water tank
4) Amount of time you manage using PV alone, not supplemented by engine or generator (Is it really 8 months?)
5) Battery size

Thanks

 

[Buck Turgidson]

Almost all our electric power comes from solar panels. We also have a large frame high output alternator (over 2kw), but with limited engine run times, its overall contribution is very little (perhaps less than 5%). As we have no generator or wind generator and are almost never in marinas, these are our only two possibilities.

Hot shower water is heated electrically in sunnier climates. Even in more extreme latitudes we can use this for much of year, but in winter we use our Reflex diesel heater. The back up is propane/butane, but this is rarely used.

Is this you?

 

[cherod]

We heat almost all our shower water via (electric) solar and battery power for about 2/3 of the year in northern climates.

If using a calorifier (we use a more versatile and slightly more efficient system) it does not make much difference to the overall total power consumed if this is via inverter and 240v AC element or a 12/24v element. However, the lower wattage 12/24 elements make it easier to utilise energy that would otherwise be wasted from the solar panels/wind generator. On the other hand, high wattage AC elements tend to be better suited to those boats regularly running a generator as the water can be more rapidly heated during the generator run time.

Hot showers without running the engine are a luxury rather than a necessity, but especially in colder climates they are a significant improvement especially for boats staying at anchor (so away from marina showers) and not moving every day ( so, ideally, the engine is not run frequently). Systems that achieve this (not necessarily electric), without the noise and complication of a generator are viable on even smaller yachts.

As well as the power needed to heat the water, some consideration also needs to be given to the much higher water consumption that will inevitably occur with the availability of regular hot showers. This is more difficult to manage on smaller yachts and is often the limiting factor preventing the ultimate luxury of long, hot showers. On larger yachts this is often not an issue.

also , having a hot shower on board with being able to lounge around afterwards and not have to trapse back along the ( possible cold and raining ) marina / pontoon is indeed a luxury worth making an effort for .

 

[noelex]

You seem to say that most of your water heating is via solar power and that's for 8 months of the year in a northern climate.

Yes, that is roughly correct. Perhaps currently more like 7 months, but we are a long way north.

It would be interesting to know:
1) Size of solar array
2) Geographic cruising location (e.g. West coast of Scotland)
3) Size of water tank
4) Amount of time you manage using PV alone, not supplemented by engine or generator (Is it really 8 months?)
5) Battery size

1) 1005w
2) We are currently above 55° N
3) Approximately 750L. We have an efficient rainwater deck collection system so in these lattitudes we can collect more fresh water than we can use, so water consumption for showers is not usually a consideration.
4) We normally produce enough solar power 12 months a year. However, so far north the sun does become very low for a couple of months so the backup large alternator is occasionally needed in the depths of winter. In a similar location last year we ran the main engine 5 times at anchor for battery charging. This was all in December and January. We are cruising full time.

 

[noelex]

Is this you?

No, that is another KM yacht. It has an amazing electrical system.

 

[Mistroma]

Yes, that is roughly correct. Perhaps currently more like 7 months, but we are a long way north.



1) 1005w
2) We are currently above 55° N
3) Approximately 750L. We have an efficient rainwater deck collection system so in these lattitudes we can collect more fresh water than we can use, so water consumption for showers is not usually a consideration.
4) We normally produce enough solar power 12 months a year. However, so far north the sun does become very low for a couple of months so the backup large alternator is occasionally needed in the depths of winter. In a similar location last year we ran the main engine 5 times at anchor for battery charging. This was all in December and January. We are cruising full time.

Sorry, I was asking about the HW tank. I've never even thought about fresh water being a limitation in Scotland. You don't need an efficient collection system here, an inefficient one is adequate (or a leaky deck ).

That is certainly a lot of solar and explains a lot. Even so, you must be very frugal with electrical power to keep batteries charged and have enough spare to heat water.

I need to recheck my figures but think this is how much water you could heat every day from 15ºC to 50ºC using 1005W solar. That's in Scotland with the panels lying flat. You get a big boost if panels are angled in winter months but only if you aren't swinging at anchor.

Month___Litres
Jan________ 6
Feb ______16
Mar______34
Apr______66
May_____83
Jun______91
Jul_______83
Aug _____64
Sep______41
Oct _____22
Nov_____ 9
Dec _____ 5

Of course this assumes it is all used to heat water, in reality you'll use most for charging. I can see that it would work with a well insulated system and not always having daily showers. About 6.5-7 months with HW and charged batteries does seem to be achievable.

I just wish I had the space for another panel, but that's always the case. Thermal solar heating is more efficient for heating water but obviously adds complexity. PV is only around 20% efficient whereas a solar shower pretty much catches everything in Greece where ambient is high and heat loss isn't important.

 

[Iliade]

I know it is a luxury but I like a long hot shower - and I mean hot. I dont know how you can produce hot water in volume <snip>

Simple - Connect the shower tray discharge pump into the shower head feed with a non-return valve betwixt 'T' piece and tank and a gas instantaneous water heater (better still a solar water heater tube) inline to keep the temperature up.

What could possibly go wrong...

 

[vas]

1) 1005w
2) We are currently above 55° N
3) Approximately 750L. We have an efficient rainwater deck collection system so in these lattitudes we can collect more fresh water than we can use, so water consumption for showers is not usually a consideration.
4) We normally produce enough solar power 12 months a year. However, so far north the sun does become very low for a couple of months so the backup large alternator is occasionally needed in the depths of winter. In a similar location last year we ran the main engine 5 times at anchor for battery charging. This was all in December and January. We are cruising full time.

battery bank size/type please?
sounds like a very efficient system, well done!

 

[ip485]

Simple - Connect the shower tray discharge pump into the shower head feed with a non-return valve betwixt 'T' piece and tank and a gas instantaneous water heater (better still a solar water heater tube) inline to keep the temperature up.

What could possibly go wrong...

Do you know this has attractions rather like the counter flow system in some arctic dwelling animals.

It is indeed perverse that we dont recover the heat we flush into the sea.

The trouble is, it would obvioulsy be a very complicated system.

Of course rather like modern car washers there could be huge efficiencies cleaning the water as it is pumped out the shower tray and just cycling it all back through the shower, a bit like wallowing in your own bath water, but requiring much less water. In fact if you arent to fussy I suppose it would only require a filter to remove the smaller particles and it would still be better than bath water, with no need for any heat recovery as long as you started with the water a little hotter than you wanted to end up with it.

 

[Rappey]

Im getting an impression that people in greece, spain etc think they get more solar but surely its much hotter there so the panels are less efficient as they heat up ?