DC Space heaters and BTUs per square feet

[Mike90250]

Even something as simple as a 55 gallon drum, with a low flow circulating pump, would store heat overnight, and slowly release it all night. 35ga might work too. Water is a very good storage medium for heat. you could also use rock in the drum, to take up space, and use less water/anti-corrosion mix too, water circulating will heat the rock, and it will still release it overnight.

Solar thermal also works on cloudy days when solar PV will generate little power (my 3,000 watt array only produces 300 watts on a cloudy day, just 10% of nameplate)

[plateauhops]

Using solar electric is very inefficient for heating. If you install solar thermal panels, you can harvest almost 3x as much BTU for either hot air or hot water.

Battery capacity for heating is also difficult, as you need batteries to be 6x your nighttime power needs, to allow for a day or 2 of shade/clouds, and to not destroy batteries by deep discharge.

Ok thanks! So, if I used a solar thermal for the day, would it store anything for the night?

For solar electric, I'm making a moderate estimate of 12 hours for nighttime, which by one calculation is 166W/h x 12= 1992 Wh. So I'd need 12kwh of batteries... Unless I could use a storage heater?
https://secure.wikimedia.org/wikiped...Storage_heater ( I don't know how it works, but maybe it could be useful. Edit: that link doesn't even work on mine)

[Mike90250]

Using solar electric is very inefficient for heating. If you install solar thermal panels, you can harvest almost 3x as much BTU for either hot air or hot water.

Battery capacity for heating is also difficult, as you need batteries to be 6x your nighttime power needs, to allow for a day or 2 of shade/clouds, and to not destroy batteries by deep discharge.

[plateauhops]

Hi, I'm looking into heaters than run on DC and am wondering if anyone has used DC heaters with batteries run on solar. [Edit: I started writing this thread because I was interested in understanding heating utilities but have updated it to include what type of multi-utility system it could be useful for]. I may plan to use LiPO4 batteries and I know that's not really common yet, but if you have knowledge on batteries that work with DC space heaters, I would be very interested in discussion.

One measurement I am reading is BTUs, and most of them recommend an average of 5,000 BTUs per 100 square feet. I'm using Tumbleweed Tiny Houses as a research model, since they are built with a standardized quality of insulation, and have many testable examples around 90-120 sq ft.
http://tinyhouseblog.com/stick-built...german-weebee/ (this one used an AC space heater, but 500 watts was turned on twice an hour for 10 minutes and was reported to keep the entire house warm).
From that link: "These houses are energy efficient when well insulated! Currently there is a electric convection heater (500W) at work until I