Solar powered motorhome question.

[russ]

I have a physics degree and, just because I'm using the expertise of others to guide me in an area that I don't know anything about, that doesn't make me an idiot. You say the technology I asked about is garbage and at least one other (seemingly informed) person was knowledgeable about evacuated tube technology and it's alternatives. I am just supposed to take your word for it that it's BS because you decreed it?

Evacuated tube tech is perfectly fine and I have never said otherwise - the way they try to present it is green.

Take whatever you choose to take - makes zero difference to me.

From the site, ''Even on a cold winter day, each solar collector will produce plenty of hot water in a short period of time. Their ability to generate heat in the dead of winter means that they perform even better in the summer.''

Both statements depend on the customer having no idea. The first statement is wild and the second wrong. Evacuated tubes outperform flat plate types in cloudy or cold weather - in full sun flat plates types are more efficient. I could list many more examples.

Look at http://www.solar-rating.org/default.htm for data for both types.

[nternal]

Look for some place that doesn't rely on BS as a sales gimmick - I mentioned before that site is long on green blather and questionable statements.

PS - Don't post the link again please.

I have a physics degree and, just because I'm using the expertise of others to guide me in an area that I don't know anything about, that doesn't make me an idiot. You say the technology I asked about is garbage and at least one other (seemingly informed) person was knowledgeable about evacuated tube technology and it's alternatives. I am just supposed to take your word for it that it's BS because you decreed it?

[russ]

Now that's an idea. In that case using evacuated tube heat collectors might work well to provide the heated water in a winter climate. I found these at: http://www.solarheatingcanada.com/

Look for some place that doesn't rely on BS as a sales gimmick - I mentioned before that site is long on green blather and questionable statements.

PS - Don't post the link again please.

[Naptown]

Now that's an idea. In that case using evacuated tube heat collectors might work well to provide the heated water in a winter climate. I found these at: http://www.solarheatingcanada.com/

Use a minimum of 60 tubes. Don't forget to provide for freeze protection by using a glycol solution enough for the record low where you intend to stay.
Check if the motor home can withstand another 900 pounds concentrated in two fairly small areas and you have room for them inside.

[nternal]

To keep an RV warm, a couple 55 gallon steel barrels, of water, hooked to a solar powered pump & 50W PV. Heat the water with roof top water panels. 100 gallons of warm water will keep the inside from freezing at night. It may not make it 65f all night, but that's what long-johns are for.

Now that's an idea. In that case using evacuated tube heat collectors might work well to provide the heated water in a winter climate. I found these at: http://www.solarheatingcanada.com/

[Mike90250]

To keep an RV warm, a couple 55 gallon steel barrels, of water, hooked to a solar powered pump & 50W PV. Heat the water with roof top water panels. 100 gallons of warm water will keep the inside from freezing at night. It may not make it 65f all night, but that's what long-johns are for.

Or look up the Solar Shed, if you have a plot of land you own, build a heat collector/storage there, hook up to your RV.

http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/solarshed.htm

Water based, hot water heating panels, circulating to heat house in Montana, DIY.

Also, folks have buried a septic tank, insulated it, and lined it, for hot water storage.

[Sunking]

it seems it can't really be done with current technology.

Sure it can the technology is over 100 years old and is pure solar power, LPG. You can store enough on a RV to last a month or two.

[nternal]

A good double pane window will retain most of the heat. Or just block it off with a piece of styrofoam.

He was talking about heat during the day anyway. Direct solar is always better than solar PV -> electric power -> electric heat.

Actually no. I'm looking to meet minimum survival requirements and one doesn't just need to survive during the day. Clearly one needs a way to store energy for this and, even more clearly, it seems it can't really be done with current technology.

[Naptown]

Moveable insulation works. it's a PITA but it works.
In an RV during the winter when heat is needed however not so much. Remember the roof of an RV is generally flat so the angle of incidence is high meaning little heat and lots of loss. Summer is the reverse, although some sun control on the exterior would help. An operating light would be better to vent excess heat from the top.

[billvon]

Until the sun goes down then a huge loss when heat is most needed.

A good double pane window will retain most of the heat. Or just block it off with a piece of styrofoam.

He was talking about heat during the day anyway. Direct solar is always better than solar PV -> electric power -> electric heat.

[Naptown]

If you are going to do that you are FAR better off just putting a skylight in. Close to 100% efficiency heating as opposed to 15%.

Until the sun goes down then a huge loss when heat is most needed.
for the most part skylights are a net loss. Too much loss vs gain during heating season and way too much gain during cooling season.

[billvon]

As for heating, I wonder how one of those small low powered 12 volt heaters would go plugged directly into a solar panel? They are little more than demisters, but if you got a 120 watt heater and plugged it into a 12 volt 180 watt solar panel it may well be enough during the day for a few hours at least.

If you are going to do that you are FAR better off just putting a skylight in. Close to 100% efficiency heating as opposed to 15%.

[noone]

Microwave can be done, but microwave cooked food really suks. They are great for popcorn, steaming veggies, and reheating coffee but that is about it.

I use a 12 volt frypan with a small AH AGM battery (but will use a LiFePo4 motorcycle battery soon for better handling of 10 to 15 amps and more usable power for the capacity plus lighter weight) charged from a 50 watt panel. Works great for ME but then I do not cook things that take too long.

[Sunking]

I know everyone says this but I actually think in SOME cases cooking is much easier with solar and 12 volts than refrigeration.

Microwave can be done, but microwave cooked food really suks. They are great for popcorn, steaming veggies, and reheating coffee but that is about it.

[noone]

nternal the only way you are going to get electric heat in an RV is to park it at an RV park and plug into the grid.

Lights are no problem using solar in an RV. Refrigeration is going to be a challenge but possible and will need a generator as backup. For heat and cooking you are going to need LPG.

I know everyone says this but I actually think in SOME cases cooking is much easier with solar and 12 volts than refrigeration.

A refrigerator is running much of the time at (usually) fairly low amps. 12 volt cooking does use more amps but for a lot of things the total power used is little (20-50 watt hours for a meal for one or two). Cooking with 12 volt and LiFePo4 batteries does make sense and even with AGM batteries can be ok. Of course for cooking things that take a while, it makes a bit less sense though still may be doable.

As for heating, I wonder how one of those small low powered 12 volt heaters would go plugged directly into a solar panel? They are little more than demisters, but if you got a 120 watt heater and plugged it into a 12 volt 180 watt solar panel it may well be enough during the day for a few hours at least.

Again though for heating unless you had LOTS of battery even an almost useless 150 watt heater for 8 hours is going to need 200 amp hours of battery...doable but a waste compared to propane.