Self Sufficient on Solar? Something Not Right !

[RJsfishin]

I'm happy w/ my small 200 watt solar, but it dawned on me the other day that if the sun hangs in here as long as I do (here in QZS) I will have saved a whole $60 of gasoline I usually burn in my Honda 1000 in a couple months. Not a terrible return on a $300+ solar investment, I thought.
But when I found myself going after my 2nd tank of propane @ 50 bucks a trip, I realized something about this self sufficient solar ain't workin quite right.
Just curious, how many are running their electric heates on some of these chilly nites,.....meaning how many more watts of solar do I need ? 🙂

Or maybe a better question,...how many solarers are still buyin propane. Maybe we don't have this solar all figured out yet ??

[MrWizard]

We have a small 200w electric heater, from lasko called a "my heat" personal space heater
designed for desk or cubicle use
October 2012 during our return from the Midwest, I would run it at night in the bedroom, outside temps in the mid 40s, draws 18~19 amps from batteries using the inverter
Since we were driving several hundred miles a day, there was no problem with the battery bank
Since then I have used it a few times to warm my desk area while on the computer late at night, but only for an hour or two
(The Oly Cat was facing the bedroom for DW),
But I could not do eight hours per night using solar only charging

[pianotuna]

Hi MrWizard,

Absolutely correct. I can do one night on battery electric heat if I restrict it to the bedroom and the temperature is above 0 c (32 f). Then it takes days to recharge the bank.

[MrWizard]

RJ
I think many of the DPs have a hydro hot system burning diesel fuel for heat and hot water
A hundred gallons of diesel will go a long time with that system

Out of all the posts about solar "PT" is the only one I remember using electric heat
And his is primarily from shore power

[EsoxLucius]

The 15,000 BTU air conditioner in my RV is also a heat pump. Hence, large battery and solar banks and a 4000 watt inverter likely would be required. Perhaps 1000AH of LifePo4 batteries at $13,000 would do the job for several hours.

[pianotuna]

Hi Rich,

If they have an absorption fridge chances are they are using propane for that purposed. The darn things use 4.8 kwh per day on electric.

[RJsfishin]

OP here,
it wadnt like I was ignorant to all this inverter, battery AHs stuff,,....I guess the question really was,....how many of those big strapper solar rigs I see out in the desert here are running propane free. There just may be some.
A heat pump is probably the place to start,.....never gave that a thought.
It wouldn't be for me, but propane could be a hassle for a 45 ft MH spending 5 months out here in the desert.

[MrWizard]

pianotuna wrote:
Hi Folks,

As a battery discharges it freezes more easily i.e. at a higher temperature.

freeze points lead acid

100% charged -67 c (-77 f)
0% charged -6.7 c (20 f)

Totally correct i said the temp backwards

i meant freezes sooner at a higher temp, not lower temp

i did say sooner, but typed lower instead of higher

[free_radical]

RJsfishin wrote:
I'm happy w/ my small 200 watt solar, but it dawned on me the other day that if the sun hangs in here as long as I do (here in QZS) I will have saved a whole $60 of gasoline I usually burn in my Honda 1000 in a couple months. Not a terrible return on a $300+ solar investment, I thought.
But when I found myself going after my 2nd tank of propane @ 50 bucks a trip, I realized something about this self sufficient solar ain't workin quite right.
Just curious, how many are running their electric heates on some of these chilly nites,.....meaning how many more watts of solar do I need ? 🙂

Or maybe a better question,...how many solarers are still buyin propane. Maybe we don't have this solar all figured out yet ??

Electric heater on solar wont do it..unless the sun keeps shining 24 hrs!!

I have diesel fueled. Espar heater that uses couple gallons a week in minus 20C.
Expensive heater,but totally worth it in efficiency and low electric consumption.as
Diesel is most powerful fuel in BTU content,

[pianotuna]

Hi Folks,

As a battery discharges it freezes more easily i.e. at a higher temperature.

freeze points lead acid

100% charged -67 c (-77 f)
0% charged -6.7 c (20 f)

[MrWizard]

Lesson 103 is the freezing point of a battery increases as the battery discharges.

NO..
i think you mean this
as battery discharges it WILL FREEZE at a lower temp, likely hood of freezing Increases

the freezing point is Decreased, it is Lower

[pianotuna]

Hi mena,

Heat pumps draw about 1200 watts. However they extract 13500 btu's of heat. A similar sized resistance heater would only output about 3600 btus.

The rub is, that below about 6 c (40 f) output from the heat pump starts to drop. So just when you need the most heat, efficiency goes down. By 0 c (32 f) they are barely better than resistance heating. The most modern ones will work to about -5 c (25 f).

That is why home heat pump systems often use pipe embedded well below the frost line. Unfortunately that won't work too well for an RV.

Don't get me wrong--if my air conditioner ever flakes out--I'll replace it with a heat pump.

[mena661]

Harvard wrote:
Lesson 102 is that when you talk about RV solar apps, 95% of the talk is about batteries.

Since the whole point of solar in a RV is to recharge/charge batteries, how can you have a discussion of solar without a discussion of batteries? But hey, I'm open to learning cause I'm definitely a solar newb.

[Harvard]

RJ, you have just experienced Lesson 101 of Solar Power.

Lesson 102 is that when you talk about RV solar apps, 95% of the talk is about batteries.

Lesson 103 is the freezing point of a battery increases as the battery discharges.

Lesson 104 is a frozen battery can split open and/or damage the plates.

Congratulations, you are becoming a seasoned veteran on Solar Power.

JMO (from my school of hard knocks, circa 1995) :B

[2oldman]

mena661 wrote:
there are members here already running A/C off inverter (few hours here and there), they just don't talk much about it. It's not like it's an impossible task, it just takes some planning like everything else.

Yep, and a heapload of amp-hours.