Dual purpose "portable" solar setup for home and RV

[Sunking]

It doesn't have to be that big for the RV but in order for the system to be reasonably functional at home I would need a large inverter and charge controller(s) so I guess the RV system size was merely a function of sunk cost in all the rest of the equipment, especially since I can get the panels for $40 each. One added note, the original owners of our 5th wheel replaced the refrigerator with a household unit - all electric, no propane - so I have 290 continuous watts and 690 peak that would always be on the system when we are in transit or boondocking.

Be careful here because there are some limits you do not want to fall outside of. Panel Wattage, Controller, Battery Capacity, and Inverter sizes need to be matched up. Batteries are the bottle neck.

Batteries have both minimum and maximum charge and discharge limits. Minimum is C/12 and max is C/8 and some can go as high as C/6. So say you have a typical 12 volt 225 AH Golf Cart battery setup. Wel it means you are going to need at least a 240 watt panel, and no larger than 500 watts. That also means the Inverter should not be larger than 500 watts. You can get away with a larger Inverter, but it will bite you in the but when you need it most.

If you run say a 1000 watts at high noon, you have the panels producing half of the power required. If you have a Battery Isolator and the engine running, the alternator will provide all the power. However say after sunset or early morning when you need that 1000 watts, even though the battery maybe fully charged, when you hit it with 100 Amps of current (C/2), the voltage sags below 11 volts, and your Inverter trips off line from under voltage. That will leave you wondering what is wrong when in reality there is nothing wrong except the design.

So be careful.

[SunEagle]

I do agree it's a lot of fun but you're right going green was not our main reason. We want to camp away from rv parks and the crowds and not use a darn generator. There are so many nice places to camp here out west on BLM land for free. Solar just makes it that much more enjoyable without the noise or using a dime on gas or diesel to run that generator. We were up in Williams two weeks ago camping there were 3 other campers within 300 ft away all had their generators on for much of the day and up to 10 pm sometimes . One class A had 300 watts of Solar which really isn't enough because there are parasitic drains so he used his gen too. The others were 5th wheels with no solar so they had to drive to town to fill their cans every couple of days. By 10 am I had 40 amps coming in, by 11 over 50 @ 14.4 volts. By 11:30 the batteries were filled. Once I got it set up right there really is almost no maintenance, that's why I put it on. It also keeps my starting batteries filled.

Lol with the medical I feel your pain.

I have about 400 watts of panels that I plan on using with my Class A if my wife decides she wants to rough it someday where there isn't any place to plug in. Still it will be hard if it is hot because she wants the AC unit on which requires at least a 30Amp connection or running the gen set.

[Mrchinup]

While installing solar in an RV may be fun I don't think the main reason is to go Green, It seems most off grid people want nothing to do with their mean and nasty POCO so they decide to cut the cord and generate power their way. Although in most cases it will be a lot more expensive they may at least feel that they are free to make their own choices.

I wish I could do that with medical insurance but alas I don't have enough relatives that work in the medical field so I pay through the nose for basic coverage hoping I don't get a serious illness.

I do agree it's a lot of fun but you're right going green was not our main reason. We want to camp away from rv parks and the crowds and not use a darn generator. There are so many nice places to camp here out west on BLM land for free. Solar just makes it that much more enjoyable without the noise or using a dime on gas or diesel to run that generator. We were up in Williams two weeks ago camping there were 3 other campers within 300 ft away all had their generators on for much of the day and up to 10 pm sometimes . One class A had 300 watts of Solar which really isn't enough because there are parasitic drains so he used his gen too. The others were 5th wheels with no solar so they had to drive to town to fill their cans every couple of days. By 10 am I had 40 amps coming in, by 11 over 50 @ 14.4 volts. By 11:30 the batteries were filled. Once I got it set up right there really is almost no maintenance, that's why I put it on. It also keeps my starting batteries filled.

Lol with the medical I feel your pain.

[Mrchinup]

Mrch...I'm not sure where you are getting 300-600w. I intend to use 6-9 panels, 165w each so I am looking at a system larger than 1000w. We don't camp in the winter so that is not an issue for us. We camp April-October and in California those months are all primarily sunny. Despite that we will still need to get more conservative with our energy use due to our poor habits at home. We have a 6K grid tie system so we are accustomed to using as much electricity as we need without much impact to our bill due to NEM. I used approx 13,000Kw last year and still had a zero electrical bill for the year. This is why I am sold on the technology. However, battery setups are far different and I am finding that out to my dismay the more I research it. Solar is significantly more costly in the off-grid world.

Sorry Tap my mistake. I was just agreeing with this.

'' Additionally, many of the places we camp are 95+ degrees in the summer (last weekend it was 106 at our campsite but fortunately we were staying at an RV park) so it would have to be big enough to run our portable 10,000 BTU air conditioner. I'm not sure 300-600w of power would be sufficient to keep the batteries charged for a long weekend in that environment.''

You could get a few hours of AC at the peak sun time during the day with 9 panels with enough batteries. My friend has 2000 + watts on his with 12 trojan 6 v batteries he runs 2 ac's for a short time during peak sun. With the area being so hot (106) I'd assume you're camping in low elevations in CA? Nice to have that solar on your house I'm sure you save a bundle. Electric in CA is not cheap.

We're in the sun too for a couple more years at the most. We head up to the mountains in Williams az and forest lakes area to beat the heat this time a year when we can. Head up to Sequoia NP you won't need the ac up there. ( My favorite park) I fully expect to be able to use an AC for a few hours a day if I had too, after I put the other two panels up and lithium batteries. The cost won't be cheap. Right now we only camp here out west so a evap cooler would work pretty well on most days when it hits 90 in the mountains.

[Sunking]

While installing solar in an RV may be fun I don't think the main reason is to go Green, It seems most off grid people want nothing to do with their mean and nasty POCO so they decide to cut the cord and generate power their way. Although in most cases it will be a lot more expensive they may at least feel that they are free to make their own choices.

RV is an exception.

[SunEagle]

Well said and very true. Just in battery cost alone you are paying 5 to 10 times more than just buying power. Used in an RV, camp site or other part time use like a hybrid system can be 100 times more expensive. So if anyone is considering going off grid to save more or lessen their CO2 foot-print is only fooling themselves as that is impossible with off-grid.

While installing solar in an RV may be fun I don't think the main reason is to go Green, It seems most off grid people want nothing to do with their mean and nasty POCO so they decide to cut the cord and generate power their way. Although in most cases it will be a lot more expensive they may at least feel that they are free to make their own choices.

I wish I could do that with medical insurance but alas I don't have enough relatives that work in the medical field so I pay through the nose for basic coverage hoping I don't get a serious illness.

[Sunking]

Mrch...I'm not sure where you are getting 300-600w. I intend to use 6-9 panels, 165w each so I am looking at a system larger than 1000w. We don't camp in the winter so that is not an issue for us. We camp April-October and in California those months are all primarily sunny. Despite that we will still need to get more conservative with our energy use due to our poor habits at home. We have a 6K grid tie system so we are accustomed to using as much electricity as we need without much impact to our bill due to NEM. I used approx 13,000Kw last year and still had a zero electrical bill for the year. This is why I am sold on the technology. However, battery setups are far different and I am finding that out to my dismay the more I research it. Solar is significantly more costly in the off-grid world.

Well said and very true. Just in battery cost alone you are paying 5 to 10 times more than just buying power. Used in an RV, camp site or other part time use like a hybrid system can be 100 times more expensive. So if anyone is considering going off grid to save more or lessen their CO2 foot-print is only fooling themselves as that is impossible with off-grid.

[SunEagle]

Mrch...I'm not sure where you are getting 300-600w. I intend to use 6-9 panels, 165w each so I am looking at a system larger than 1000w. We don't camp in the winter so that is not an issue for us. We camp April-October and in California those months are all primarily sunny. Despite that we will still need to get more conservative with our energy use due to our poor habits at home. We have a 6K grid tie system so we are accustomed to using as much electricity as we need without much impact to our bill due to NEM. I used approx 13,000Kw last year and still had a zero electrical bill for the year. This is why I am sold on the technology. However, battery setups are far different and I am finding that out to my dismay the more I research it. Solar is significantly more costly in the off-grid world.

Spoken like a true believer. Off grid will always be more expensive then grid tie users. The cost difference goes up if the usage is high. My guess is that batteries will be hard to justify for a while so the best way to save is to find ways to reduce your electrical usage and match your system to that lower number.

[Tap2112]

Hi Tap: I can tell you from experience that 300 to 600 wouldn't be close to being enough for what you want. I do know a little bit about RV Solar though. In the winter with a few clouds you will be cut in half. I have two 435 watt SP panels that I can tilt on my Class A, works nicely for now. In the winter you really need that tilt. With as many panels you want most likely you will have some in the shade. Another friend has 12 older panels on his, he gets shade spots.When we go out for 10 days or so we have plenty of power for what we want right now. In two years we'll go on the road for long stretches. I have 4 extra panels 2 in case anything goes wrong and two more that will go on top before were full time off grid. I know people who live off grid with 2000 watts and many with 350 or so, one of my best friends does it with about 350. He's very conservative with his power. I like the Idea of the residential fridge too, if my 4 door propane fridge dies I'll do the same.

I really like using the big panels with high voltage, less drilling into the roof, less panels, smaller wire, ect. I lose much less than 1% to the controller but lose 2-3% more in the conversion from high voltage to low voltage. If you live out west in a low humidity area you might want to try a evap cooler they really do work, my friend has a couple. We never use our 6k generator while dry camping. GL

Mrch...I'm not sure where you are getting 300-600w. I intend to use 6-9 panels, 165w each so I am looking at a system larger than 1000w. We don't camp in the winter so that is not an issue for us. We camp April-October and in California those months are all primarily sunny. Despite that we will still need to get more conservative with our energy use due to our poor habits at home. We have a 6K grid tie system so we are accustomed to using as much electricity as we need without much impact to our bill due to NEM. I used approx 13,000Kw last year and still had a zero electrical bill for the year. This is why I am sold on the technology. However, battery setups are far different and I am finding that out to my dismay the more I research it. Solar is significantly more costly in the off-grid world.

[Mrchinup]

[QUOTE=Tap2112;n353548]Thank you guys for your responses...



It doesn't have to be that big for the RV but in order for the system to be reasonably functional at home I would need a large inverter and charge controller(s) so I guess the RV system size was merely a function of sunk cost in all the rest of the equipment, especially since I can get the panels for $40 each. One added note, the original owners of our 5th wheel replaced the refrigerator with a household unit - all electric, no propane - so I have 290 continuous watts and 690 peak that would always be on the system when we are in transit or boondocking.

Additionally, many of the places we camp are 95+ degrees in the summer (last weekend it was 106 at our campsite but fortunately we were staying at an RV park) so it would have to be big enough to run our portable 10,000 BTU air conditioner. I'm not sure 300-600w of power would be sufficient to keep the batteries charged for a long weekend in that environment. My 6-9 panel guesstimate was to make sure we had enough power for everything else after fridge and A/C were satisfied. Also, the used panels are now more than 8 years old so they are not putting out 165w anymore. The controllers would need to handle the original open current specs but real life output I'm sure will be down about 10%.



Hi Tap: I can tell you from experience that 300 to 600 wouldn't be close to being enough for what you want. I do know a little bit about RV Solar though. In the winter with a few clouds you will be cut in half. I have two 435 watt SP panels that I can tilt on my Class A, works nicely for now. In the winter you really need that tilt. With as many panels you want most likely you will have some in the shade. Another friend has 12 older panels on his, he gets shade spots.When we go out for 10 days or so we have plenty of power for what we want right now. In two years we'll go on the road for long stretches. I have 4 extra panels 2 in case anything goes wrong and two more that will go on top before we're full time off grid. I know people who live off grid with 2000 watts and many with 350 or so, one of my best friends does it with about 350. He's very conservative with his power. I like the Idea of the residential fridge too, if my 4 door propane fridge dies I'll do the same.

I really like using the big panels with high voltage, less drilling into the roof, less panels, smaller wire, ect. I lose much less than 1% to the controller but lose 2-3% more in the conversion from high voltage to low voltage. If you live out west in a low humidity area you might want to try a evap cooler they really do work, my friend has a couple. We never use our 6k generator while dry camping. I don't see any panels going over 1 dollar a watt most are much less. GL

[AWS]

I've put two small RV solar systems together, both have 100w panels and PMW controllers one on each of our RV's. They allow us to run my wifes c-pap, the roof vent most of the night and lights, the fridge is propane while boon docking. For the power you are needing I would look to one of the new very quiet generators, weight, cost and setup would be much easier, I doubt if you could even hear it with the AC running.

[Sunking]

BTW, Sunking I just checked the specs of the unit and you were spot on with the energy rating. Here is the unit I have:
http://www.sears.com/royal-sovereign...p-04274902000P

Well thanks, but knowing how to calculate EER is grade school math formula EER = BTU / Watts. Just from that formula you can rewrite:

BTU = Watts x EER
Watts = BTU / EER

Now think about this. What if EER = 25, and BTU = 10,000. How many watts for the same cooling? 10000 BTU / 25 = 400 watts.

Goberrment mandates lowest EER of a air conditioner is 10. That means the unit you are looking at is the most inefficient model money can buy. You get what you pay for. I understand Hot Climates. Spent most of my life in TX, NV, and OK. Now I live where it never goes below 55, and never warmer than mid 80's in Panama. However with the humidity, mid 80's can get uncomfortable. We also get a lot of rain. Just about every day in wet season in the mornings or late afternoon. Does not last long. Dry season rains twice a week briefly in the mornings.

[Tap2112]

That would be a very low efficiency window shaker with an EER 10,000 BTU's / 950 watts = 10.5. As low of efficiency as Uncle Sam will allow made. Double the cost and equipment of a 5K unit. A 5th wheel trailer is not insulated like a home office setting out in the broiling Sun.

It would take a minimum 1500 watt panel to run off solar for a hour or two around noon. You would have to have at least a 12 volt 1000 AH battery or 24 volts @ 500 AH. Either way is a 700 pound $2000 battery. for just a few hours of cooling. Good luck with that.

Fair enough.

Due to the part of the country I live in some form of A/C is a required. For instance, today it is 106 degrees where I live and it's 100+ for much of the 200 mile surrounding area where we often camp. If I can't even run a portable A/C unit, let alone a roof mount, then I can't do much boondocking without a noisy and expensive generator. That my defeat the purpose of doing a solar installation in the first place. Maybe I just got a little overly ambitious wanting to add solar because I believe in it so strongly.

BTW, Sunking I just checked the specs of the unit and you were spot on with the energy rating. Here is the unit I have:
http://www.sears.com/royal-sovereign...p-04274902000P

[Sunking]

I never suggested I was going to use a 5K btu unit. That was Sunking's response in another thread that he was posting here for reference. I have a 10K unit that uses about 950 watts

That would be a very low efficiency window shaker with an EER 10,000 BTU's / 950 watts = 10.5. As low of efficiency as Uncle Sam will allow made. Double the cost and equipment of a 5K unit. A 5th wheel trailer is not insulated like a home office setting out in the broiling Sun.

It would take a minimum 1500 watt panel to run off solar for a hour or two around noon. You would have to have at least a 12 volt 1000 AH battery or 24 volts @ 500 AH. Either way is a 700 pound $2000 battery. for just a few hours of cooling. Good luck with that.

[Tap2112]

You are not going to cool a camper with a 5k btu AC unit. much less power that unit from Solar. Most campers have 12k and 18k BTU air conditions due to the lack of insulation. a 5k BTU unit is no where enough, Might not even be enough to remove the humidity created by 2 bodies, much less the heat uptake of direct sun exposure. The weight of the batteries needed would load down your camper and cost more fuel to move said camper around. Still need AC, get a generator.

I never suggested I was going to use a 5K btu unit. That was Sunking's response in another thread that he was posting here for reference. I have a 10K unit that uses about 950 watts and it quickly cools my 180 sq ft home office when I don't want to run my 5 ton central air unit if nobody else is home. It would easily cool the living space in my 5th wheel during the day if I were to close the bedroom and bathroom doors and could be moved to the bedroom in the evening if necessary.

Whether it can be run strictly from solar is another story, but the cooling capacity of this unit is plenty for my RV needs based on the history of my usage at home.