Solar Panels

Well I think I found my solution. After reading the most recent newsletter from Tiffin, there was an article about a couple that boondocks 300 days a year in their Phaeton DP. The wife works remotely from the RV and, for them to be fully functional and comfortable, they found that a 2000 watt solar panel system takes care of their needs. I found a complete 2300 watt system with panels, batteries and inverter for just under $4000. I think between that and the generator that would work for us.

Thank you everyone for your insight and input.

fyrflie wrote:
https://www.parkedinparadise.com/solar-calculator/
This is just one of multiple places to look to answer your question.

But, rather than build a system just for the RV, why not look into building a true off-grid power system.

Well, you stepped in it with that last question. The realistic, factual answer is that none of the "alternative energy" options available today are ready for prime time. This is why none of them would exist were it not for the massive government (taxpayer) subsidies they receive. Can you say "Solyndra"? Tesla is another example. Wouldn't exist without subsidies, big ones, subsidies that YOU pay for through your taxes.

rlw999 wrote:

valhalla360 wrote:
So you are looking at a very large solar array, very large battery array and a large inverter charger...realistically, it will be cheaper to maintain and fuel your existing 7kw generator. Even if you have to replace it every 8-10yrs.

I think you're underestimating the cost of running an RV generator 24x7.

Running an Onan 7000 for 6 months 24x7 would use close to $10,000 of gasoline (0.7 gph at half load), and after 4000 hours running 24x7 in the Arizona heat, it'll probably be time to replace it at the end of each season. (plus he'd be changing oil + filters ever 150 hours (or less) which would cost around $1000/year

So that's probably close to $15K/year in total expenses. A 20KW solar array plus a few tesla powerwalls would cost around $50K. So if he's really doing this long term, he'd break even with solar after 3 or 4 years, and he wouldn't have to deliver 120 gallons of fuel to his site every week.

He'd probably save some money buy buying a small 8KVA prime power diesel since fuel cost would probably be half, it would last a lot longer, and would need fewer oil changes.

If there is power within a few miles of his property, it could be cheaper to pay the power company to run power there.

24x7 maybe, if he's out there all summer long (all I can think is glutton for punishment) but if he's doing that, bucking up to get grid power run to the site starts making sense even if it's quite expensive.

Now if the OP is out there for weekends or a week here and there in the summer, he still needs the massive solar system to cover the power demand during hot periods but the rest of the year, it's oversized. A generator would use far less fuel in that scenario.

So really, the OP needs to share what he thinks is usage of the site would be.

valhalla360 wrote:
So you are looking at a very large solar array, very large battery array and a large inverter charger...realistically, it will be cheaper to maintain and fuel your existing 7kw generator. Even if you have to replace it every 8-10yrs.

I think you're underestimating the cost of running an RV generator 24x7.

Running an Onan 7000 for 6 months 24x7 would use close to $10,000 of gasoline (0.7 gph at half load), and after 4000 hours running 24x7 in the Arizona heat, it'll probably be time to replace it at the end of each season. (plus he'd be changing oil + filters ever 150 hours (or less) which would cost around $1000/year

So that's probably close to $15K/year in total expenses. A 20KW solar array plus a few tesla powerwalls would cost around $50K. So if he's really doing this long term, he'd break even with solar after 3 or 4 years, and he wouldn't have to deliver 120 gallons of fuel to his site every week.

He'd probably save some money buy buying a small 8KVA prime power diesel since fuel cost would probably be half, it would last a lot longer, and would need fewer oil changes.

If there is power within a few miles of his property, it could be cheaper to pay the power company to run power there.

"We declined the solar panel option as I don't think 2 solar panels would run the A/C during a 115 degree AZ summer."

Neither will 3 or 4 panels.

We are in a different environment, but have a 9K ground solar system and am adding two Tesla Powerwalls with 27K. Check out Ironridge if you want a ground unit.

This should cover about 98% or more of our requirements. I am still connected to the grid, but if I were not connected, I would use a generator to cover the other 2%. This is a reasonable solution.

I designed and installed most of the components myself, but do have an engineering background.

You asked what size solar system you would need in the Tuscan area. 7K would suffice. Then you'll need 2 batteries.....ugh. That solar will cost you about $15,000. The batteries another $10,000. No way I would leave that stuff sitting unattended for a long period out in the middle of nowhere. Diesel generators are a better bet than a propane generator. They use less fuel and last a whole lot longer. You'll have acreage, so, you could put it far enough away that the noise would not bother you. I just read about wells drying up all around the Tuscan area. If you made your system large enough, you could lease out spaces to Snow Birds, and use that money to put an even larger system in?

LP system out this way are not cheap, and the LP is running above the price of Premium fuel right now. We just had a friend switch out from LP to to total electrical due to the cost of LP for heat and hot water heater and stove. They went thru the winter and came out ahead on cost and the house was still warm. Plenty of shops in Phoenix area that do this and they are good at it.

Assuming 2 air/con units running flat out in Arizona heat...let's say 3kw constant demand (24/7).

That means you need a total of 72kwh generated per day.

Solar panels don't generate their rated output 24/7. A good estimate is 4 times the ratted kilowatts (1000 watts) in killowatt hours. So, you are looking at around 18kw of solar panels...call it 20kw since you will lose some power converting it to battery storage and back again.

Now you need something to store those slippery electrons or they just fly away. That means a battery bank. So if we figure around 2pm, the 20kw of solar panels is putting out less than what you are using and doesn't pick up to that level again until 10am the next morning, you need to cover 20hr of use at 3kw or storage of about 60kwh.
- Traditional lead-acid batteries, you don't want to use more than 50% of the available power, so you will need around 120kwh of batteries.
- Lithium are expensive but you can use 80% without worry, so you need about 75kwh of batteries (just shy of what a Tesla has).

So now you have a way to generate power and a way to store it...but it's stored as DC power. You need a way to convert that to AC power which means an inverter. Well if it you are pulling 3000w, just get an 3000w inverter...except no, 3000w is the continuous draw once the air/con compressors are turning. To start those compressor motors takes 3-4 times the power. If you are careful (or add a device that only allows one to start up at a time, you may see 1500w + 1500w *4 or about 7500w momentarily. You need to buy an inverter that can handle a start up load of 7500w (often it's difficult to find the continous vs startup rating on inverters).

So you are looking at a very large solar array, very large battery array and a large inverter charger...realistically, it will be cheaper to maintain and fuel your existing 7kw generator. Even if you have to replace it every 8-10yrs.

Perhaps I will look at LP powered generators as well. A 10kw is about $3000 and consumes about 1 gal per hour at half load. A 1000 gal LP tank is about $2500.