Solar powered motorhome question.

[nternal]

Is it possible to equip a class C or B motorhome with solar panels that are capable of providing enough electrical power (stored on batteries) for minimum survival needs (heating, refrigeration and lighting) in a moderate climate with an average winter/summer temperature range of -5 to 20 celsius or 20-70 fahrenheit) ?

[Naptown]

Heating no use propane
Lighting yes if you use high efficiency bulbs
Refrigeration maybe.
do plan on running the genset after a cloudy day or two

[nternal]

Heating no use propane
Lighting yes if you use high efficiency bulbs
Refrigeration maybe.
do plan on running the genset after a cloudy day or two

I'm wondering of it's possible to survive (meeting only the most minimal needs) without fuel of any kind other than solar power. For heating I'm not talking about being comfortable, I'm talking about simply not freezing. Any cloudy periods that couldn't be supplemented with stored battery power would be shut downs.

[Naptown]

Again Maybe.
depends on where you are, what minimal energy use is and how much space for panels and weight for batteries.
Oh and how much you can afford to spend. the last one is the kicker.

[nternal]

Budget.

I'd be looking for something durable and permanent so this is NOT where I'd be looking to save money. I have no idea how much money one would need to make this work but would $20,000 get it done?

[Mike90250]

Solar PV = no heating. Maybe a cup of water on an Induction Hotplate. Heat is what fire is for.

You will find winter time, is the hard item, with shorter days, more cloud cover. You will be trading off using a led light or two, against early death of your batteries. Discharging flooded lead acid batteries below 50%, will begin to greatly shorten their life, especially if you have limited recharging (solar) capacity.

A single 100w panel, with 4 hours of sun, will keep a "Group 24" size battery charged, and you can use a 20 watt light, for about 10 hours a night. Add more loads, you get less time. 400wh of sun, gives you 200wh of recharge/discharge, roughly.

[nternal]

Panel efficiency?

Mike90250, I get it that one isn't going to be able to capture much usable energy from the sun. I'm an absolute newb and confused about 2 things:
1) You claim a 400wh of sun gives 200wh hours of recharge but I was under the impression that even the very best cutting edge panels are only about 40% efficiency?
2) Also, aren't lithium ion storage cells the current state of the art?

I guess I would need a massive set of panels to do what I'm proposing or maybe... Could this technology be used on an RV:http://www.solarheatingcanada.com/

[nternal]

Are full spectrum panels available yet?

I've read about recent advances in full spectrum solar panels. Any thoughts on when these might become available?

[Naptown]

Mike90250, I get it that one isn't going to be able to capture much usable energy from the sun. I'm an absolute newb and confused about 2 things:
1) You claim a 400wh of sun gives 200wh hours of recharge but I was under the impression that even the very best cutting edge panels are only about 40% efficiency?
2) Also, aren't lithium ion storage cells the current state of the art?

I guess I would need a massive set of panels to do what I'm proposing or maybe... Could this technology be used on an RV:http://www.solarheatingcanada.com/

Those 40% cells are actually available. however the only one that can afford them is NASA. They are not commercially available in any kind of quantity and can run into the thousands of dollars per watt. Not something you would be putting on your RV roof.
Lighting and Refrigeration are the two things you will most likely be able to run. And refrigeration in the winter means for the most part in the out of doors or cooled by ambient. Luckily this cold part of the year with little sun is the time when there is a reduced need for refrigeration.
Heat is probably not possible unless you can come up with a wood burning boiler that would sit outside but moving it around could be an issue.
Moving around and plumbing a number of thermal collectors could be an issue too. and having enough storage to keep you through a night or a day or two of no sun would be a huge storage mass. (4-500 Gallons of water in a well insulated vessel)

[Sunking]

1) You claim a 400wh of sun gives 200wh hours of recharge but I was under the impression that even the very best cutting edge panels are only about 40% efficiency?

You are confusing two different parameters. You are confusing panel efficiency with system efficiency. They are not related to each other.

Mike is speaking to over all efficiency of an Off-Grid Battery System which is 50%. The panels generate 400 wh to generate 200 wh of usable power.

You are speaking of panel efficiency which is only important with reference to physical size or area of the panel. Best panels on the market are about 20% and very expensive. A square meter of surface has 1000 watts of electrical energy at high noon on Equinox and Solstice. So if the panel is rated at 20%, and 1 square meter in size it will be rated at about 200 watts.

2) Also, aren't lithium ion storage cells the current state of the art?

Yes and no. The kicker is expense for top of the line A123 System batteries beiong used in production electric vehicles. A good flooded lead acid deep cycle battery will outlast a lithium, and cost about 12 to 15 cents/watt hour. A Lithium will cost upwards to around 50-cents/watt hour for a low grade Chi-Com unit and up to $1 or per watt hour for high grade LFP pouch or prismatic cells.

Lithium advantage is energy density which is mission critical for electric vehicles as their specific density runs up to about 120 wh/Kg vs 45 wh/Kg for a lead acid cell. Weight is not an issue for Solar PV systems, but critical for a EV.

[nternal]

Those 40% cells are actually available. however the only one that can afford them is NASA. They are not commercially available in any kind of quantity and can run into the thousands of dollars per watt. Not something you would be putting on your RV roof.
Lighting and Refrigeration are the two things you will most likely be able to run. And refrigeration in the winter means for the most part in the out of doors or cooled by ambient. Luckily this cold part of the year with little sun is the time when there is a reduced need for refrigeration.
Heat is probably not possible unless you can come up with a wood burning boiler that would sit outside but moving it around could be an issue.
Moving around and plumbing a number of thermal collectors could be an issue too. and having enough storage to keep you through a night or a day or two of no sun would be a huge storage mass. (4-500 Gallons of water in a well insulated vessel)

Electrical heating looks like it's a no go but this vacuum tube "heat pump" idea looks promising. Would this work on a motor home do you think? Check it out:http://www.solarheatingcanada.com/

[nternal]

P.S.

Thanx for setting me straight Sunking.

BTW, does anyone have any thoughts on the recently developed full spectrum solar panels that are 70% efficient and, in theory, cheaply manufactured?

[russ]

I've read about recent advances in full spectrum solar panels. Any thoughts on when these might become available?

You might be talking about Off Grid Solar in Florida (I believe that is the correct name)? That has been well documented to be nothing more than a scam from what I have read.

[russ]

Electrical heating looks like it's a no go but this vacuum tube "heat pump" idea looks promising. Would this work on a motor home do you think? Check it out:http://www.solarheatingcanada.com/

1) The claims made by the company are a bit magic - if you check up on both flat plate and evacuated tube type exchangers their overall efficiency is quite similar -
a) In a cold or cloudy situation the evacuated tube type are generally better
b) Evacuated tube type can produce hotter water but less volume
c) In a mild sunny climate the flat plate type win hands down

2) Their chatter about converting 92% of incidental UV is of no meaning - except to impress newbies

3) Solar for infloor radiant? I have looked at that before and have come away totally unimpressed - takes storage and many panels.

They must be having fun trying to sell their product in the land of cheap electricity - even with the rather inflated claims.

The site is dedicated to the fuzzy headed green lot that love such inane chatter.

[nternal]

You might be talking about Off Grid Solar in Florida (I believe that is the correct name)? That has been well documented to be nothing more than a scam from what I have read.

Nope, here's a very recent article: http://www.photonics.com/Article.aspx?AID=50200
and... one of the companies that I believe is currently developing the concept : http://www.sj-solar.com/