Using solar panels to lower electric costs

[rthomaslyons]

We go to Yuma for a couple of months in the winter and have noticed fairly high electricity charges each month in excess of $100 per month plus surcharges. When we take our new motorhome down there this year I was thinking of taking our 180 watt portable solar panels down with us and maybe run the fridge and hot water on propane and use the electricity for day time Air/Conditioner and a portable electric heater at night when it’s needed. Does this make any sense? We must pay something for the power that is converted to 12vdc. We are likely going to have to move the motorhome to get propane a few times anyway...

[babock]

If you are paying by the kilowatt hour you might save a couple dollars. If you really can get 180W and 6 hours equivalent sun, you are only generating 1KWH per day. If they charge you $0.15 per KWH, you will save a whopping $4.50/month.


Way cheaper to use electricity than propane more than likely. Not even going to talk about the convenience factor of having to run and fill propane all the time.

[RACarvalho]

In my understanding no, it doesn't.
My background is boating and I have being following solar tech for more than 20 years and despite the huge price drop during this period, solar it still doesn't make financial sense if your horizon is not constant use for a long period of time.
180w is nothing in the context of a decent refrigerator and a 600w array of solar panels + charge controllers + battery + inverter will not make you save money.
A small $300+ 2000W gas generator(if you don't have a generator in your motorhome) with maybe a battery upgrade would be the most cost effective solution if you don't use the AC.
If you want to use the AC, then a ~$700 3100W generator will do it.

[ependydad]

Originally Posted by RACarvalho

A small $300+ 2000W gas generator(if you don't have a generator in your motorhome) with maybe a battery upgrade would be the most cost effective solution if you don't use the AC.
If you want to use the AC, then a ~$700 3100W generator will do it.

If they're in a park that charges electricity, I'd be surprised if they're allowed to run a generator. Plus, I'm betting you would negate the savings in cost of fuel.

[Hclarkx]

Originally Posted by rthomaslyons

We go to Yuma for a couple of months in the winter and have noticed fairly high electricity charges each month in excess of $100 per month plus surcharges. When we take our new motorhome down there this year I was thinking of taking our 180 watt portable solar panels down with us and maybe run the fridge and hot water on propane and use the electricity for day time Air/Conditioner and a portable electric heater at night when it’s needed. Does this make any sense? We must pay something for the power that is converted to 12vdc. We are likely going to have to move the motorhome to get propane a few times anyway...

The solar can only help. Given the sun Yuma gets, 180W could help a lot ... if you use a lot of energy at 12V during the day. As you are thinking, t[he solar will only pump energy into your 12V system to charge the battery or supply 12V load. As such, it may reduce the energy your converter must deliver into the 12V system when the sun is shining. Do you use a lot of 12V energy during the day?

You may find that the converter holds the 12V system voltage high enough that the solar controller thinks it is working into a well charged battery and thus will back off and do little or nothing. To fully utilize the solar, you may need to turn the converter off and run 12V loads from the battery (day and night) with the solar panel re-charging the battery daily. That wear-and-tear on the battery and the monitoring that goes with it could be more than the energy is worth.

If your fridge is like mine, it's very efficient on propane and terribly inefficient on 120V electricity. My 6 cu ft fridge draws about 300W and racks up a lot of hours every day. A 30# propane tank can run it for months. Running the fridge on propane should save $$ if the electricity is expensive. Though the big users are A/C and electric heat so the dent in the electric bill may be modest.

[RACarvalho]

Originally Posted by ependydad

If they're in a park that charges electricity, I'd be surprised if they're allowed to run a generator. Plus, I'm betting you would negate the savings in cost of fuel.

You are looking for the lowest operation cost here.
If you can't use the generator, I really doubt that solar will bring you any savings....
energy is charged in Kw/h.
A 180W panel in a good day would produce 0.9Kw/h/day (assuming 5 hours of full 180W production).
From that 0.9Kw (assuming you can generate that), you need to discount the inverter / charger efficiency and the battery charging rate (the battery may not absorb the quantity of energy that you are generating while it is available)....
Now, compare 0.9Kw/h/day with the power consumption of whatever you will be powering and you will see that 0.9Kw/h/day (which is not real) will not power you for long.
In case generator can't be used, I would run the fridge and water heater on gas and all the rest on the park power...
That would be the lowest cost... in my view.

[lacamastraveler]

Originally Posted by rthomaslyons

We go to Yuma for a couple of months in the winter and have noticed fairly high electricity charges each month in excess of $100 per month plus surcharges. When we take our new motorhome down there this year I was thinking of taking our 180 watt portable solar panels down with us and maybe run the fridge and hot water on propane and use the electricity for day time Air/Conditioner and a portable electric heater at night when it’s needed. Does this make any sense? We must pay something for the power that is converted to 12vdc. We are likely going to have to move the motorhome to get propane a few times anyway...

APS in Yuma charges from about 11 cents to 24 cents per KWh, depending on your plan and time of day.

[TitanMike]

The only reason that solar works with RV's, especially using low wattage panels (<100 watts each) is because they are only used to recharge batteries. This is fine for someone boondocking in moderate weather and doesn't need the high current required to run one or two A/C units.

The power appetite from the A/C unit(s) and the rest of the trailer is like the appetite of a 2 year old and a teenaged football player.

Only way to save money on electricity in Yuma is to get used to a warmer interior like 80 degrees instead of setting the thermostat down to 72, the mythical "Room Temperature.


Building an RV mounted Solar System to save money on electricity is like buying a $40,000- $50,000 Tesla because you want to save money on the gas your paid for vehicle is using. Only time this pays off is when you don't HAVE any electricity and need a quiet way to charge your batteries daily.

[camaraderie]

Under ideal conditions, 180w panels might produce 45-50 DC amp hours...not remotely enough to run any large AC loads like an A/C or residential fridge or microwave but with an inverter, enough for a computer or TV type load.
I would not amount to a hill of beans in terms of electricity costs saved. Just plug in and forget about it unless you are prepated to spend thousands more on passive solar and massive battery banks and associated accessories.
For occasional boondocking with A/C a decent generator in the 1800-3000w range is probably the cheapest way to go. Consensus says Honda & Yamaha make the best reliable & quiet ones but there are lots of other choices. Most can't be used at all in conventional RV parks and are good for boondocking in no amenity state, local and federal land.

[dahagen]

My experience with solar panels is that they are only really good for keeping your battery up when boondocking. Change out your bulbs with LEDs and enjoy the warm weather. Open your windows (unless you have the frameless windows). You don't need to run the AC much in Yuma in the winter. Also, for propane, get an Extend-A-Stay adapter and you won't have to move.

[rlocicero]

When everything is all said and done, you will probably save the price of a cup of coffee a day at Dunkin’ Donuts. Is the screwing around worth it???

[Tom48]

Originally Posted by babock

If you are paying by the kilowatt hour you might save a couple dollars. If you really can get 180W and 6 hours equivalent sun, you are only generating 1KWH per day. If they charge you $0.15 per KWH, you will save a whopping $4.50/month.


Way cheaper to use electricity than propane more than likely. Not even going to talk about the convenience factor of having to run and fill propane all the time.

I can't vote for the accuracy of those numbers but the concept is solid. Solar panels recharging your batteries is great for dry camping but the fraction of your electricity that goes to charging the batteries when you are on hookups is relatively small.

large grid-tied systems on your house can substantially reduce your electric bill or eliminate it but it would probably take 1200 watts of solar and a substantial investment in Victron equipment and lithium to build enough of a power system to make a meaningful dent in your Park billing for electricity

[Larry-NC]

Originally Posted by rthomaslyons

We go to Yuma for a couple of months in the winter and have noticed fairly high electricity charges each month in excess of $100 per month plus surcharges. When we take our new motorhome down there this year I was thinking of taking our 180 watt portable solar panels down with us and maybe run the fridge and hot water on propane and use the electricity for day time Air/Conditioner and a portable electric heater at night when it’s needed. Does this make any sense? We must pay something for the power that is converted to 12vdc. We are likely going to have to move the motorhome to get propane a few times anyway...

Why would you use a portable electric heater at night instead of the furnace?

[Tom911]

Look how much the cost of electricity has gone up in the last 40 years? Ok now look how much the price of gasoline, insurance and propane have gone up? Who is taking advantage of who?

[formerFR]

NO, unless you have a 'HYBRID' inverter, which can take in Solar Power to offset/lower the need for the 120v Shore Power.

Why will a normal Inverter, or just adding Solar Panels not accomplish a savings?
Well, it has to do with how 'solar power' works for typical RV scenarios. Solar panels provide a power output, typically 12v, directly to your House Batteries, NOT directly to any appliance or devices, especially NOT to anything that using the 120v power you are paying for from Shore Power, because those items are powered outside of your House batteries, or thru your Inverter(which is basically 'bypassed' when you are on Shore Power).
Solar power to give an offset to 12v devices and appliances only will doubtfully save you any 'money', especially since the very cost of adding 'expensive' solar is, well, expensive!

The best way to 'save' power bill costs when in your RV is to use other sources of power, such as propane, though it, itself, will have a cost, too. And, some don't like the 'chore' of having to find propane, or carrying bottles to a trading station, etc. It may also be true that using propane doesn't necessarily lower your overall costs, even if you have to pay 'more' for electricity, overall.

Heating and Air Conditioning are always the 'big' costs when RVing, whether parked or traveling. Either your Shore Power or your Generator are going to be needed to power them, or Propane for the heat. If you go outside and stand next to your propane Furnace outlet, you'll quickly see how inefficient the propane might be...a lot is lost to the outside.

[tomkatb]

Spent the month of July in Houston!

Electricity charge was $250!

Both ac units pretty much ran 24/7.

This is not what solar was designed for. It is for boondocking in nice weather out west.

Some day it will be better.

[TitanMike]

Originally Posted by rlocicero

When everything is all said and done, you will probably save the price of a cup of coffee a day at Dunkin’ Donuts. Is the screwing around worth it???

When everything is all said and done------ It usually means more is said than done.

If one factors in the cost of the equipment one will have to get their coffee at the highway rest area when they're handing it out free to tired drivers.

I personally don't believe there is enough room on the average RV to install enough solar panels to handle the A/C load in the hotter parts of our country. One might need a trailer with panels that can be extended while parked like the solar panels on the Space Station. The trailer could also carry the battery bank necessary.

Something else to consider. The more one tries to capture solar energy, store it in 12 volt batteries, they then have to run an inverter to power their A/C unit(s). That's heat that is being generated by the inverter is usually somewhere inside the RV and now the A/C has that extra heat load to deal with.

Not sure I understand why people seek out places so hot that even nature's critters spend most of their days underground. Or the humidity is so high you have to walk around with a towel around your neck like you're living in a sauna. Maybe if a job takes them there but when retired and not tied to any one place? Isn't there somewhere with more moderate temperatures.

Just wondering.

[TitanMike]

Originally Posted by Tom911

Look how much the cost of electricity has gone up in the last 40 years? Ok now look how much the price of gasoline, insurance and propane have gone up? Who is taking advantage of who?

The answer to that last question is "Everyone".

Workers want more money
People that hire workers need more money to hire them
People want more Government Services
Government needs more tax revenue
People paying taxes want more money
Go back to the first line on this list.

It's a great big, vicious, circle.


The only reason Electricity hasn't gone up in price as much as gasoline is the fact that those who sell us the electricity are a regulated Utility. If Fuel Prices were regulated in the same manner as Electricity we'd probably have a lot less fuel. Who'd want to drill wells for crude oil if they couldn't make enough money to cover exploration and production costs?

[Tom48]

Originally Posted by tomkatb

Spent the month of July in Houston!

Electricity charge was $250!

Both ac units pretty much ran 24/7.

This is not what solar was designed for. It is for boondocking in nice weather out west.

Some day it will be better.

running those air conditioners 24 hours a day is going to consume a lot of electricity and with no more solar than you can get on the roof of an RV solar will not make a dent in reducing the bill.

What would probably help a great deal is covering your windows with reflectix and taking other steps to enhance the insulation of your coach. there are dozens of YouTube videos suggesting weak points in the insulation for all of us including such things as putting foam panels in the back of cabinets that face exterior walls.

air conditioning is just going to labor endlessly to overcome not only the heat but the humidity in Houston. Good luck with that.

[babock]

I would never go anywhere where I need to run an AC 24/7.

In fact, I won't go anywhere I need AC. Mine has been run just a couple times to know it works.

I don't have solar to save money. I have solar so I don't have to bring a generator.