Everyone, thank you for your posts! Hopefully this can be a learning experience for everyone!
BackAlley, a special thanks!
I love hearing your feedback.
To answer some of your questions,
(1) As far as the flattop propane usage, it only runs on one (out of three) burners. It stays way hot and produces more than enough cooking heat without cooling down - we are only warming tortillas on one side. We will only be on the road 5 days max at a time, so the propane will more than last - I have no doubt about that.
(2) Currently, we have two 25-lb tanks for a home-town location. I calculated 50-lb tanks for the needed increased propane supply on the road. But I had no idea whether they made 50-lb tanks!
I guess they don't. And now with the new calculations, it seems two 100-lb tanks would be needed for worry-free transit.
(3) We decided to go with a 240w solar installation on the roof. More for the environmental standards to help us get approved for festivals. But it will still help our energy efficiency and off-grid longevity.
We've also concluded that we will only be off-grid for 24 hours twice a week, since almost every festival provides electrical hookups. At home base, we have freezer and fridge (F&F) storage. So doing some quick math, it seems that running a propane genny for 1 day to power the F&F while on the road will use 48 lbs of propane (...the steamtable, lights, music, etc will only be on when hooked up to an electrical supply) while a propane-powered F&F will use 3 lbs per day.
It seems more efficient to go propane in the long run. Averaging 5 days a week on the road, a propane-powered F&F uses 15 lbs per week. If we go with an electric F&F, the genny will be on for 2 days max, using 100 lbs a week. At $1 per pound of propane, it will be additional $85 per week for propane. Buying a propane-powered F&F will cost an additional $1100 over electric appliances. So it will only take about 13 weeks to make up the added initial cost by going with a propane F&F.
However, add in the solar setup and the electric F&F setup uses even less electric while off-grid. Plus add 3 or 4 deep cycle batteries that we can charge while on the grid and it reduces our off-grid electricity consumption even further. So figure that now we're down to only about 12 hours off-grid twice a week. So it takes 26 weeks to make up the additional cost for the propane F&F.
I think that if I was looking for maximum off-grid capability, propane-powered appliances with a supplementary solar setup would be the way to go. But for 2 days a week off grid (1 day every 3 days), it seems more efficient (at least in the 2 year term) to go with electric appliances. Hopefully we can build our next truck with maximum off-grid capabilities!!!
Unless I'm missing something here, it seems sensible to go with an electric F&F. And for shorter travel times, it would take even longer to make up the initial cost of propane appliances. Feel free to correct me if I'm wrong. Again, thanks for your help! Very much appreciated!
<message edited by BelizeNut on Sat, 11/5/11 10:51 PM>