Need solar help!

Hence the need for an energy audit to determine sizing.

My older MH has a parasitic draw of 8a a day (including fridge). Normal total daily usage is 20-25a. 100w of solar and an 80ah battery works great. If you have a 35a draw before you even turn on a light you will need much more.

I use two 12V fridges. Together they easily use 65AHs daily.

Not sure what is typical as there many variables.

HTH;
John

If you read my posts on this thread I made it clear I was speaking about my RV. Trackrig has similar loads amounting to 35 amp-hours.

I do wish the fridges were not such hogs. Mine draws 1.5 amps when the gas valve is open and 0.5 amps when it is not active. On a duty cycle of 2:3 per hour, that works out to about 1.17 amp-hours X 24 hours = 28 amp-hours per day. And yes, this is from real life data measured in October when the ambient temperature was 20 c (68 f).

The point is that for many (if not all) RV'ers a 100 watt solar panel may not be sufficient to their needs. Suggesting otherwise does solar a disservice, which results in an attitude that "solar doesn't work" or "solar is expensive".

The reality is that a properly sized solar charging system is the nearest anyone ever gets to a "free lunch". It is a one time cost. Do it right the first time.

pianotuna wrote:
So the fridge doesn't need power to run? Let me know how that works for you.

The Dometic RM182 in our bus doesn't require any electricity to run on propane. It works very well for us, thanks for asking.

The DM2652 in the TT does require electric power. But, it only uses electricity if you switch it on. That's not a parasitic load, which is what was being discussed. Stop trying to create a strawman.

And, the DM2652 only draws about 0.7 A, and would be much less than that if I disconnected the anti-condensation heating strip. That's about 17 Ah per day. The parasites might add to 1 or 2 Ah, which still gets nowhere near the 35 Ah which was claimed to be a typical parasitic load.

The OP should become aware of how much different things consume, and how much they're on. I mentioned lighting, a 30' could easily have 3 or more double lamps with 921 bulbs on during the evening for 4 hours or more. That's 30+ Ah.

mike-s,

So the fridge doesn't need power to run? Let me know how that works for you.

pianotuna wrote:
35 amp-hours is what my particular RV draws, and there are others who have quoted that figure.

The biggest draw is the fridge. Duty cycle is 40 minutes on and 20 minutes off. I suppose you could turn the fridge off--but it would certainly be less than convenient.

You said "parasitic draw." That doesn't include anything you can turn off. LP/CO detector and radio (for station memory) are the two most common. The refrigerator is not a parasitic load.

As an example, I was running led bulbs, propane fridge, 42 inch led television, furnace with temps usually in high 40s to high 50s. I was using Four GC 2 batteries and 520 watts of solar through a Bogart PWM controller. We used the television several hours and also ceiling fan or vent fan.It would usually fully charge but I also tilted the panels.

mike-s,

35 amp-hours is what my particular RV draws, and there are others who have quoted that figure.

The biggest draw is the fridge. Duty cycle is 40 minutes on and 20 minutes off. I suppose you could turn the fridge off--but it would certainly be less than convenient.

pianotuna wrote:
Parastic loads are often around 35 amp-hours per day.

No where near. That's like a 1.5 A continuous draw. Nothing you can't turn off draws anywhere near that.

If you short on charging, you will always be operating on the low end of the voltage scale.
If this works for you,.....gets you thru the weekend or whatever, then gets fully charged when in storage, its ok, but operating that way will take its toll on battery life.
Even w/ 300 watts, I operate that way at times when our coastal fog hides the sun for a big part of the days, and rather than fire up the generator, I just let'er run on low voltage for a day or 2, it keeps working fine.