solar space heating BTUs

2 Posts
Oct 15, 2008 03:03 pm
solar space heating BTUs

Can someone clarify the output ratings on the SolarSheet and SunMate heaters?  I'm trying to heat an open area that is currently serviced by 2 electric baseboard radiators with a combined wattage of 4500.  I think that equates to about 14,000 BTUs.  The SunMate is rated at 19,000 BTU per DAY "class C".  Is there some way I can relate that heat output to the electric baseboards so I can determine if the unit will be effective?

Also, my house faces southeast.  Is there any benefit to a solar heater if the house does not face true south?

I'm still learning...thanks for the help!
22 Posts
Oct 16, 2008 08:30 am
Re: solar space heating BTUs

The SRCC has rated the air heaters with the same standard as the water heaters, BTUs per day.  The Sunmate is rated at 15kbtu/day, the Solarsheat 1500G at 10kbtu, 1500GS 14kbtu/day (the two can be ganged together for 24kbtu/day), and the small 1000G at 6kbtu/day.

Keep in mind this is supplemental heat, it will not work at night or much on cloudy days.  I just installed a Solarsheat 1000G in my 760 sqft home a few weeks ago.  On sunny days, it turns on at 9:15Am and blows from 85 - 120 degree air into my house.  (I have a thermometer sensor in the pipe in the wall to monitor).  The defuser on the wall spreads it out so it's not just a stream of heat in your face.

Amy Beaudet
Tech Sales Rep
AltE Store
2 Posts
Oct 16, 2008 10:39 am
Re: solar space heating BTUs

Amy, thanks for the reply.

I was leaning towards the SunMate because it has the higher BTU rating while also being a smaller panel.  It also has a 10 year warranty compard to 5 years for the Solarsheat.  However, the Solarsheat has the advantage of having the solar-powered fan inside.

But I still don't know how to measure the output of one of these panels compared to my electric baseboards.  I sense that the panel will supply some heat but that the electric baseboards will still be needed even during the daytime.

Can both of these panels be mounted sideways like you did.  I would guess that the most efficient operation would be to have the inlet at floor level (cold air flows downward) and the output at ceiling level (warm air rises).  Having the two vents at the same height and only a few feet from each other make me think that the warm air would simply be sucked back into the panel before it could flow into the room.

Finally, do I need direct sunlight for the panels to work?  My house faces southeast.  I would bet that it's the rare house that has a true southern exposure!

Thanks again for the reply and photos.
1 Posts
Feb 16, 2009 03:12 pm
Re: solar space heating BTUs

If you go to this web site you will find a calculator for converting watt-hours into BTU. From the SRRC specs, in one of their "rating days" a SunMate panel should produce about the same heat as your electrical resistance heating of 4500 watts does in one hour. Of course, the actual output of the SunMate depends on your location and how the panel is located.

If the panel does not face within about 10 to 20 degrees of south, your results will be quite a bit less. You can go to my web page at to read about my experience with the SunMate panels.

I selected the SunMate over the Solarsheat because the SunMate, according to the SRRC tests, does better under lower temperatures and partially cloudy skies. As far as the input and output of the panels being near each other. This does not appear to cause any problem. And yes, the SunMates can be mounted sideways, but the standard mounting brackets may not work. You should check with Environmental Solar systems on the mounting the units sideways.
« Last Edit: Feb 19, 2009 11:39 am by Bernard Waxman »
2 Posts
Feb 16, 2009 04:01 pm
Re: solar space heating BTUs

I own three of the SunMate panels. Two are vertical and one horizontal. The horizontal one needs to be special ordered with a check valve flap on the intake to prevent thermo-siphoning. With a Southeast orientation I expect that you will get 50-75%(guesstimate) of the SRCC ratings (assuming no shading problems). My panels are mounted 15 degrees East of true South and run from 9:00 to 3:00 on clear cold days.  These are well made panels and will work well given good sun exposure.
33 Posts
Feb 18, 2009 05:16 am
Re: solar space heating BTUs

4500 watts = 15360 btu's it's a simple energy->heat conversion. Sun gives 1000 watt per square meter at 1 solar power which is 3404 btu's.

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