Utilizing Solar with FHU

[TomG2]

I most often park with Full Hookups. I am trying to figure out how to use solar energy to reduce my electric bill and of course be available when I do occasionally park off the grid. I enjoy my air conditioner, microwave, etc. so I do not want to simply pull the plug while parked and plugged into shore power. I am thinking of a very modest system as I cannot see investing several thousand dollars for something that might only save me ten.

[Almot]

TomG2 wrote:
I did not want to make anything complicated. I asked if my investment in solar might be useable while I am in a park hooked to shore power. Not going to be wiring in transfer switches, etc. I will probably just flip the main 120 volt breaker off in the converter

You mentioned microwave. When you flip main 120V breaker off, you will have to run 120V off the inverter.

Transfer switch is a necessary safety measure if you don't want to fry your inverter and/or batteries. You can do without this switch but the risk will be higher.

Your only other choice (avoiding both risk and complications) would be to stop using 120V devices while on solar, though this would be uncomfortable and would reduce your energy savings to $1-$2 per month (compared to shore power).

[red31]

TomG2 wrote:
I asked if my investment in solar might be useable while I am in a park hooked to shore power.

with the converter off (FHU) or unplugged (dry camping), one can operate 12v items like furnace fan, lights, water pump, fantastic fan ... off the battery/solar.

[pianotuna]

Hi TomG2,

Yes the solar is usable, but the benefits are small.

200 watts of solar will be just fine to replenish the battery bank, if you have switched to led lighting. Simply turn off the converter. Do monitor the DC voltage once a day (say just before bed) to make sure the battery bank is not deep cycling. The microwave uses NO 12 volt power, and the air conditioner "sips" 12 volt power. The main 12 volt user other than lighting is the gas valve on the fridge. If you are using the fridge on 120 volt then that too is an extremely small load.

TomG2 wrote:
I asked if my investment in solar might be useable while I am in a park hooked to shore power. Not going to be wiring in transfer switches, etc. I will probably just flip the main 120 volt breaker off in the converter then monitor my batteries and power usage. I can always flip it back on for microwave and air conditioner. Sort of "dry camping" in place.

[MEXICOWANDERER]

Massive systems atop houses and businesses are a long-term project that start to repay their cost after several years. A tiny system would be like flaming a Zippo lighter in hopes of reducing an LPG heating bill.

We have a tiered pricing system down here that starts off at the eqvt of 6 US cents a kWh. But surpass 500 kWh in a 2-month period and the kWh price soars to near fifty cents a kWh. Cutting total kWh usage would be feasible even though panels are anything but cheap.

Periodic outages (like 6 days total in a 30-day span) make solar voltaic or generator power mandatory. Heavy shade stops my solar plans, cold.

Run the kWh numbers according to your cost. If a thousand watts of panels cost "X" amount of dollars, yet a kilowatt of power only costs 12 cents, Imagine the thousand watts, plus inverter as costing a thousand dollars. One thousand dollars divided by 12 cents is 8,333 and you only get the 12 cents when the sun is at it's peak. Long-Term may be an understatement. And a thousand watt system is by no stretch of the imagination "small". It could power a tiny air conditioner for the peak sun period. This is not a rational plan.

[TomG2]

I do not want to make anything run backwards. I did not want to make anything complicated. I asked if my investment in solar might be useable while I am in a park hooked to shore power. Not going to be wiring in transfer switches, etc. I will probably just flip the main 120 volt breaker off in the converter then monitor my batteries and power usage. I can always flip it back on for microwave and air conditioner. Sort of "dry camping" in place.

[pianotuna]

Hi,

It is possible to save about 1 KWH per day with a 200 watt solar system. Compared to 0.15 per kwh it is going to take a very long time to recoup the costs.

If you DIY and search carefully costs may be under $1 per watt for panels, and controller. But such a system would not allow for future upgrades which would make boondocking convenient.

Do you have a way (such as a kill-a-watt meter) to measure consumption on your converter?

Another way to limit use would be to have a hybrid inverter charger that would limit your shore power intake to say 15 amps. Extra power as needed would be drawn from the battery bank, and the solar would help to recharge the bank.

It might take some time to find the "ideal" setting for the intake power limitation. For example if the air conditioner is running 24/7 it may be unwise to limit to just 15 amps.

I do often only have 15 amp shore power and since I have a medium size battery bank I can "live" with that limit while the RV "pretends" it is a 30 amp supply--taking energy from the battery bank when I cook, etc. When the load drops off the charger replaces the energy that I've used from the battery bank.

But the bottom line remains the same. With 200 watts you would only save $0.15 per day on a 365 day average.

[time2roll]

If you want to turn the meter backward you will need a grid tie inverter.

[TomG2]

Transfer switch? In what circuit? Automatic or manual?

[Almot]

TomG2 wrote:
I was curious as to the ease and benefit of using the solar output while enjoying full hookups.

Benefits - see above.
Ease - you need to install and use inverter and transfer switch.

[TomG2]

The dry camping question has been asked and answered many times already on the forum. I was curious as to the ease and benefit of using the solar output while enjoying full hookups.

[Almot]

TomG2 wrote:

What is not clear? I asked, "I wondered if I could get any benefit from solar while in my RV park."

You also said that investment will be for dry camping. For most people adding a solar on dry camp makes sense. For some it doesn't. Questions to answer: How long dry camping, how often, how much AH used per day on dry camp (not counting A/C), can you DIY.

The very question "benefit from solar while in my RV park" is a no question. Yes, you will benefit - IF you are going to have solar anyway. But it won't be much. Again, there are questions to answer: energy use, electricity rates, solar size, can you DIY.

[TomG2]

Almot wrote:

TomG2 wrote:
I wondered if I could get any benefit from solar while in my RV park. The investment will be made for dry camping, but I hate to think that it would not give me a few dollars in return for just sitting there ready to go. If it is simple as turning off the converter, I will give it a try. If I have to plug/unplug every few hours, then it is not worth the experiment.

Scenario is still not clear.

What is not clear? I asked, "I wondered if I could get any benefit from solar while in my RV park."

Dry camping will be handled with a combination of solar and generator. I only want to know the procedure and benefit, if any, of using solar where I have full hookups. Sorry, can't be any clearer than that.

[red31]

what's your dry camping power usage?

[MrWizard]

Yes you turn off the converter, and use the solar to maintain the battery and power the water pump, thermostat etc..
But those savings will be pennies a day.
If you seldom dry camp, and it is only for a limited amount of time
An extra battery or two, might be a better investment, with no need to add solar