Building a Solar Electric Houseboat

[tim123]

Hi Luc,
  thanks for sharing your build. I'm really impressed with your innovation and craftsmanship. 

I have a few questions, I hope you don't mind...

- Have you calculated the heating requirements for the boat on a cold winter day?
   i.e. given the R-values, the surface area, and the inside & outside temps - you can calculate how much heat you'll be losing, and hence how much you need to add...

- How will you be powering and heating the boat during winter? Is there any opportunity to have a wind-generator, for example?

- Have you considered using wave-power at all?
   It's really easy to have a float connected to a (geared) DC generator, and it works at night too.
   Potentially much cheaper than solar.
   Not much use in winter, or on a trailer, though...


Tim

[gotoluc]

Hi Luc,
  thanks for sharing your build. I'm really impressed with your innovation and craftsmanship. 

I have a few questions, I hope you don't mind...

- Have you calculated the heating requirements for the boat on a cold winter day?
   i.e. given the R-values, the surface area, and the inside & outside temps - you can calculate how much heat you'll be losing, and hence how much you need to add...

- How will you be powering and heating the boat during winter? Is there any opportunity to have a wind-generator, for example?

- Have you considered using wave-power at all?
   It's really easy to have a float connected to a (geared) DC generator, and it works at night too.
   Potentially much cheaper than solar.
   Not much use in winter, or on a trailer, though...


Tim

Hi Tim, thanks for your interest and positive comments.

No, I have not calculated the heating requirements. The internal space is very small, only 8 feet wide x 18 long. Insulation value is very high, R20 in the walls and R40 in the roof and floor. I'm integrating a glycol  radiant floor heating system which will be heated by a small on-demand propane water heater that delivers 14 KW of heat power at 88% efficiency.
I have no worry that the heating system is more than adequate, even a temperatures of -40.

The boat is powered by an electric drive system which will be powered by a 2 KW Solar panels array (above the top deck).  I may use a wind generator in the winter if the panels don't supply enough power, however I doubt that.

Wave power is good if you're in an area with wave action, however, this is not my case, I'm mostly on a river system.

Thanks

Luc

[tim123]

Hi Luc,
  14Kw eh? That's more than my house!

I've done the calcs. I had to use UK metrics, but it looks pretty favourable... I think the values are right, but it's the first time I've done it - so I could have made a mistake. It's not rocket science though...

For living space 8ft x 8ft x 18ft = 2.5 x 2.5 x 5.5m

End walls - 2 x 6.5 m2
Side walls - 2 x 13.75 m2

R-value for 100mm Kingspan (metric) = 4.5 m2 K / W

Assumed temperature difference: 60 Degrees C - (inside +20, outside -40)

AREA x TEMPDIFF / RVAL = WATTS

End walls @ 6.5m2  = 83 Watts x 2
Side walls @ 13.75  = 183 Watts x 2

Total for all walls = 533 Watts

If floor & ceiling have 200mm Kingspan, they both lose 91 Watts

Total Losses = Heating Requirement = 716 Watts


Tim

PS - that's ignoring any insulation afforded by the fiberglass, glue, plywood, wall coverings etc...

[gotoluc]

Hi Luc,
  14Kw eh? That's more than my house!

I've done the calcs. I had to use UK metrics, but it looks pretty favourable... I think the values are right, but it's the first time I've done it - so I could have made a mistake. It's not rocket science though...

For living space 8ft x 8ft x 18ft = 2.5 x 2.5 x 5.5m

End walls - 2 x 6.5 m2
Side walls - 2 x 13.75 m2

R-value for 100mm Kingspan (metric) = 4.5 m2 K / W

Assumed temperature difference: 60 Degrees C - (inside +20, outside -40)

AREA x TEMPDIFF / RVAL = WATTS

End walls @ 6.5m2  = 83 Watts x 2
Side walls @ 13.75  = 183 Watts x 2

Total for all walls = 533 Watts

If floor & ceiling have 200mm Kingspan, they both lose 91 Watts

Total Losses = Heating Requirement = 716 Watts


Tim

PS - that's ignoring any insulation afforded by the fiberglass, glue, plywood, wall coverings etc...

Thanks Tim for the reply and energy loss calculations.

I know the 14 KW looks high!  I got it from the ebay page of the heater I bought: http://www.ebay.com/itm/Haier-Gas-LPG-Instantaneous-On-Demand-Continous-Flow-Tankless-Water-Heater-/261274268626?pt=LH_DefaultDomain_0&hash=item3cd528f3d2

I forgot to mention is my ceiling will only be 6-1/2 feet high, but one way or the other the heating requirement looks to be quite low.

One thing I was wondering is how long my propane tank will last. There must be a way to convert propane to Watts output by its weight. I was thinking of using a 15 pound tank.

Here are the average monthly temperatures in Ottawa, Canada, in degrees Celsius:

Month	ºC
January	-10
February	-8
March	-2
April	6
May	13
June	18
July	21
August	19
September	14
October	8
November	1
December	-7

So from June to September we don't need heat but the rest of the 8 months we do. Maybe with the above you can find the average daily Watts needed for those 8 months and from that find how long a 15 pound propane tank will last.

Thanks for your help and sharing

Luc

[tim123]

Hi Luc,

For liquid propane
• 4.16 litres= 1 therm = 100,000 BTU = 29.3701 KW

http://www.lpg-solutions.co.uk/how-will-a-supplier-calculate-the-cost-of-lpg-to-an-end-user/