This blog got a comment from Will who questioned the wisdom of a solar panel array of 48 volts, "48 volts? I question your installer as to weather he knows what he is doing. These should be in parellel for 12 volts." Here is a quote from the Renewable Energy Design Guide & Catalog section on the OutBack MX60 MPPT Charge Controller: "The OutBack MX60 allows you to use a higher output voltage PV array with a lower voltage battery - such as charging a 12 or 24 VDC battery with a 48 VDC PV array. This reduces wire size and power loss from the PV array to the battery/inverter location and can maximise the performance of your PV system."
I received a partial estimate from Solar Wind Works for $9,011. This covers the cost of the hardware (except for cabling) and does not include shipping charges or installation costs. I sent them a check on Friday and depending upon when the hardware arrives, the installation should commence soon.
Last night I spent my first night in the motor home. I slept in the cab over bed and it proved to be pretty comfortable. I'm not sure that this will be how I will sleep when I finally get on the road. Since I have the two couches in the lounge area, I may decide to sleep there and then the cab over bed area could be used for additional storage space. George of the "The Adventures of Tioga and George" blog sleeps below and had his cab over bed area converted to storage cabinets when he was down in Mexico. One potential problem with this idea is that of the weight that the items in the additional storage space could impact on the total weight of the vehicle.
For those of you who are not RVers, one can only have so much weight in the vehicle so you are limited in the amount of stuff you can carry safely. I think that the total amount of items for this size rig is about 2,000 lbs. The solar panels, inverter/charger and additional batteries will add quite a lot of weight and decrease the amount of weight left for storage of items.
I am also thinking of getting a motor scooter and carrier to hang off of the rear as a dinghy. This would also impact the total weight of the vehicle on the road, specifically on the rear axle. Several of the posters in the Yahoo group "Life with Lazy Daze RV" suggested that I should seriously think about towing my Honda Accord instead. I rode a Lambretta motor scooter when I was attending college and enjoyed it, especially the mileage. I love my Honda too, it's paid for and gets pretty good mileage for a car but if I am going to have a toad, I might like to get something smaller like a VW convertible or a Jeep to be able to get off road. I wish the VW Thing was still in production but the ones still available are now getting more expensive since they are now collectible.
I hope to take this rig out in the sticks for camping. I seriously considered getting a Sportsmobile 4x4 van conversion before finally commiting to this Lazy Daze. I also thought about getting a Sprinter class B conversion. These two possibilities would have cost more than a brand new Lazy Daze. It would be nice to have another vehicle to scout for new places to camp and run to the store for groceries but I think for the time being, I'll try it out without a toad or dinghy. I just hope I don't end up on some road stuck out in the boonies with no place to turn around. Maybe I'll get a bicycle or moped. Who knows? Any comments?
Here’s hoping that I’ll see you On the Road with Gary.
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8 comments:
Hi Gary,
I certainly have to agree with your decision to go with 48 volts - you will find the people in the know almost always use or eventually arrive at 48 volts - dealing with 1/4 of the current for the same wattage is the key.
I might argue some about the grandious system you are starting out with - but you are totally right on the 48V - stay with it.
John Calypso
Gary, just curious, where do you store the dish and tripod?
Hi David,
When I first got the dish from HughesNet and assembled it, I tried storing it in the front passenger seat area. Since I plan to travel solo, I can use that area for storage. It fit okay in the passenger seat area. Since then I have added the Dustyfoot parts but I think that the dish will still fit. I think that I'll be able to store the tripod in the same area too but I haven't tested it yet. If it all cannot fit in the passenger seat area, I will store some of it in the over cab area (except when I want to sleep there). The tripod could also be stored in the shower area if need be.
Hey Gary,
Since you live in Truckee, I suggest your first road trip be to the Burning Man art festival in the Black Rock Desert. People come from around the world to participate and you are only four hours away, much of it down hill. As a former, and possibly unreformed hippie you are likely familar with the event. If you aren't, I highly recommend you check burningman.com. Its quite possibly the best opportunity to to recapture your mispent youth you will ever have, if only for a week. However, the playa in late August can be a harsh environment and you may not want to put your new toys to such a test right out of the box. Playa dust is eternal. Good luck on your adventures.
George B.
Miami Beach
Gary,
I like your idea for a moped or something small like that. Ms. Tioga is a 27' Class C and George goes everywhere in her although he will sometimes use his bicycle, Mr. Trek. I (personally) don't think you need a toad with such a small home.
I know that George converted his cabover to a storage area and has a single bed on one side of the rear but Andy slept in the cabover and converted his rear to storage and a computer desk. So there's examples of doing it both ways. I think I would prefer the cabover since you're alone but it is -your- home.
I would like to second the Burning Man festival although I haven't been to one. I've read some -awesome- decriptions, though. Hope to make it at least once. 8-)
Robert in Houston
Hello again
I have been busy so I could not read the posts. I still have to question useing 48 volts. I also question people's qualifications who thinks useing 48 volts is the key. What you quote from the seller of the controller is nothing more than selling HYPE. It is very misleading to advertise a solar panel by power in watts only. You must also look at the volts and current. VOLT * AMPS = WATTS A battery on a 12 volt system needs 14 volts with a suficent current to charge. You cannot try to put 48 volts into a 12 volt battery. The battery will quickly be destroyed. Current is the key here, The more current you can put into a battery at 14 volts the quicker it will charge. A current meter on your alternator will bear this out, I am not talking about a volt meter. I figure your system at 48 volts will put out about 14 amps current. 14 amps is all you have, you need to add up all of the current draws from your system. If you are only charging at 14 amps and you are drawing 20 amps from your battery you will quickly have a dead battery. You could have a 1000 volt solar panel at 7 tenths of an amp and still have 700 watts but it would be useless for you. Remember V*A=P in watts. A charge controller is a device place in series with your battery and solar panels to regulate the voltage to a safe value to charge your battery. It will consume a certain amount of power on its own. How much power is consumes depends on how much voltage it has to drop and at what current it provides. Useing ohms law and kirchoffs law I came up with some figures.
AT 48 VOLTS to drop 48 volts to 14 volts at 14 amps. 14 volts times 14 amps equals 196 watts going into the battery. The charge controller is eating 34 volts at 14 amps. 34 volts times 14 amps equals 476 watts it is eating for itself. This power is NOT going to the battery, it is going up as heat to the enviroment.
Ok let's say you rewire it for 24 volts, sure you will have to use heavier wire, but how much more exspensive is it. The advantage to this is more charging current for your battery. The current will double to 29 amps. If your RV is pulling 20 amps from the battery and the charge system is charging the battery at 29 amps, you will have a surplus of 9 amps. Your battery will be happy. Let's figure the power.
At 24 volts the charge controller must drop 24 volts to 14 volts at 29 amps. 14 volts times 29 amps equals 406 watts going into the battery. The charge controler is dropping 10 volts accross itself at 29 amps. Let's do the math, 10 volts times 29 amps equals 290 watts it is burning up as heat.
Now let's go to the more common solar panels of 18 volts for a 12 volt system. Your charge controller has to only drop 18 volts to 14 volts. Again you will have increased your current. I have done the math of 700 watts divided by 14 volts equals 38 amps. Again we will have to increase the wire size, how much more exspensive can it be for the efficency to be obtained. Again let's do the math
An 18 volt solar system to be dropped to 14 volts at 38 amps. 14 volts times 38 amps equals 532 watts going into the battery. The charge controller has to drop 4 volts at 38 amps. 4 times 38 amps equals 152 watts the controller is consuming. So if you are pulling 20 amps from the battery and the charge system is putting in 38 amps to the battery you have a surplus of 18 amps.
I challenge anyone to dispute ohms law and kirchoff's law and there are some laws of physics involved also.
I have worked in the electronic and electrical fied for well over 30 years and I have worked on cars for well over 40 years. I have seen these sellers of solar panels hype the wattage of solar panels to mislead people. Wattage dosen't mean a damn thing untill you take in account the voltage and current. Remember V*A=P in watts. I wonder just how much do these people really know and how many are just plain shysters trying to make a fast buck. I have a bone to pick with the so called installers. You would not believe how many so called experts, has no idea of what they are doing. I also have a bone to pick with the charge controller manufactors and sellers. They hype the systems up to make people beleive you will get more power out of the system than you are putting in. The laws of physics says this is impossible. There's always inefficenies in every thing. As for useing heavy wire. I have bought wire and yes at time it can be costly but I have found it isn't all that bad. 6 gauge wire at 40 amps should be good for 75 feet. 8 gauge should be good for 40-50 feet. 10 gauge wire should be good for 20 feet. How big is your motorhome, judging from the pictures it isn't much more then 25 feet long. As for my figures there is a little error because I rounded off the numbers, I didn't want to type long numbers in decimals.
Will
Dear Will -
I have a Master's degree in Electronic Engineering from Stanford and have had many solar systems including three in my earthship in Pueblo, Colorado as well as two solar systems in my homes in Mexico. But don't take my word for it - ask anyone that YOU might consider a professional about the pros and cons of these variations. You will find that most people that have used lower voltage systems migrate to 48 volts eventually because it is more efficient and uses less current by a factor of 4 (yes - I know ohms law). One might argue that it is overkill for a smallish motor home - but no one that knows solar will argue that 12 volts is a better way to go than 48 volts - no one.
To suggest that ohms law will give you the answer here is rather short sited and lacking in responsible engineering because efficiency, cable loss and the type of devices that have to handle high current are certainly part of the equation - better check this out before you spout off what an authority you consider yourself.
You might also want to get a spell checker by the way.JEEEEZ!
John Calypso
Gary - I might add that Will's math about voltage drops etc. are quite wrong. There are some amazing charge controllers these days that utilize all available panel voltage when charging. I think maybe Will hasn't kept up with things perhaps resting too much on the laurels of his past experience. I mean with all due respect I went to Stanford 35 years ago ;-)But I continue to follow the progress of photo voltaic technology.I might suggest Will do the same.
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