Hi GuysOkay i have been given the task of fitting a 240v generator to an RV in to one of it's closet spaces.It needs to power one 240v socket, charge the RV battery (standard battery on trickle charge) and power the shower which doesn't have a boiler as such it heats the water on a 'as and when' basis. Low wattage lighting also two 40W lightsThere is plenty of space. so I thought how about try and fit a generator than runs on renewable energy.I just need to know what direction I should be looking in. HydrogenSolar (Doubt it)Bio-FuelAnything else?Also, is it best to convert an existing design of generator, buy a new one or build one from scratch to fit?Any help would be truly awesomePeace
Electric heating of your hot water is very inefficient since you have so much heat rejected in the exhaust for every KWHr you make. Your best bet would be to use the exhaust heat and/or jacket cooling water from a biofueled generator to heat the hot water tank. You get very high efficiencies from that combination. I have seen such devices talked about (see the link below) for years, but have recently seen one that is actively under development. It may be a bit oversized for your RV, however, since it is for a house. You may be able to just add a heat exchanger on the exhaust and use a small, thermostatically controlled pump to circulate the hot water from the tank through the tubes. Biofuels are not as available as gasoline, but if you research where you are going, you may find they are more prevalent than you think. Also, the generator will be able to run on fossil fuels as well, giving you a back up in case you can't find biofuel. Hydrogen is interesting, but I can't think a commercially available generator that runs on it. And you would still have the efficiency issue unless you recovered the exhaust heat like I have said for the biofuel. I can't think that solar would work well, you have such a limited amount of collection surface on the roof, and lugging around batteries and/or hot water is also inefficient. I have been on trips where it was cold and cloudy for a week, solar would not do well under those circumstances.
You need the power level, and I suspect it is very high. The shower is the problem, as it will use several thousands of watts only for a few minutes, then zero power for the rest of the time. Everything else is a hundred watts or so. If you could switch to a tank hot water storage system, where you can heat the water slowly, with perhaps 500 watts over hours of time, so it is ready for those showers. Perhaps even less. Hydrogen is not practical, as it is not readily available, neither is bio-fuel. Your best bet is solar, as you have plenty of space on the roof for the panels. You will need a charge controller, a few sealed deep-discharge 12 volt batteries, and an inverter. The batteries can store up power for the times you need it. The number of batteries will be determined the needed power levels. Again, the shower predominates. Get readings of watts used and time lengths, so you can calculate the number of batteries. .
