New rv solar from scratch

thedogatemyhomework · March 2015

First let me just say this place is amazing. I googled for an hour before I found this site. Say hello to my bookmarks folder!

Ok so I have a 1978 GMC Coachman RV, It once had a 3.5kw generator, but it is long gone now. When I had it, and when it worked, it barely ran the rooftop AC and struggled badly to run it and anything else besides. it got ripped out and stolen one day when I was not looking, and I have been tethered long enough to suit me for the rest of ever. I need solar in the worst way, like, yesterday..

I would imagine I want probably 4kw of 110V power (this is a guess based on the generators performance) or more.to insure there is plenty of power to run the rooftop AC and still run everything else...but how that converts into a 12/24 volt system is way beyond me. Inverters? charge controllers? batteries? what!? Luckily I have a friend who is good at soldering and the general all around building of stuff who promises to teach me soldering and basic solar-panel-assembly...so I should be able to cut some costs. Installation and even building of the solar panels from stacks of individual cells wont cost me one red cent---and I wont be doing it on my on so that has to be a plus---not that I couldn't, I just have not learned how, yet. It would be helpful if I knew what to buy to make it all copacetic.

That is where you fine people come in.

Imagine in your mind's eye an old RV with a 30 amp Cutler-Hammer panel and a large 110v to 12v transformer (that needs to go---it pushes 16.6v!! Yikes!). I have room for 200+ square feet of panels, and enough cargo area for up to 10 standard truck-sized batteries, and plenty of extra space for wiring and electronics and stuff.

What does it need to never need a tether ever again? How many batteries? What size charge controller? What size inverter? What wattage cells? Mono? Poly? My head is spinning I am so confused....

Can someone please help make sense of all this for me? I got my wallet out ready to buy some solar stuff, but I have no clue where to begin.

Cheers and thanks ever so much in advance!

The dog ate my homework! That is my excuse, and I am sticking to it. (:

BB. · March 2015

Welcome to the forum TDAMHW!

My first suggestion is to know your loads, and look at consevation... It is almost always cheaper to use less/get more efficient appliances, etc. than it is to build out a larger off grid power system.

A small system (~1 kWH / 1,000 WH) per day will give you lights, laptop computer, small fan, TV...l

Add an electric refrigerator, and you are looking at 2-3.3 kWH per day. etc.

So--Designing a system to support the loads you need--Always a good way to start.

Other ways, say you have 200 sq ft of roof space. That will (roughly) give you--Some back of the envelope calculations:

200 sqft * 13.468 Watts per sqft (panels) = 2,694 Watt array

Assuming 3-4 hours of sun minimum (for ~9 months a year minimum--Depending on where you will travel/live/seasonal usage):

2,694 Watt Array * 0.52 typical system eff * 3 hours a day of sun = 4,202 Watt*Hours per day (northeast)
2,694 Watt Array * 0.52 typical system eff * 4 hours a day of sun = 5,603 WH per day (US southwest)

4-5.6 kWH per day (9 months of the year, roughly), is actually a pretty good size system and would power a very energy efficient home quite nicely (100 kWH per month ~ 3.3 kWH per day). Lights, laptop computer, small fan, Refrigerator, well pump, clothes washer, etc.

Now--If you choose a battery bank... If you want 4 kWH for two days of no sun, 50% maximum discharge on a 48 volt system:

4,000 WH * 1/0.85 inverter eff * 2 days storage * 0.50 max discharge * 1/48 volt battery bank = 392 AH @ 48 volt battery bank

Or around 16x golf cart size batteries (8x 6 volt @ 200 AH batteries in series for 48 volts x 2 parallel strings). Can you fit that / carry the weight in your chassis (and do you want to)?

Anyway--A lot more details to talk about--But it sort of gives you an idea of the math, questions, and the typical minimum vs maximum size system that you are talking about.

If your main appliances are mainly using 120 VAC for your power--Get a Kill-a-Watt type meter and start measuring your loads--And getting an idea of how much energy each uses per day of use.

Writing the numbers down (watts, peak watts, WH per day, etc.) and doing some math will give you a greater appreciation about how much power our typical appliances use--A lot more than you think.

And figure that off grid power will cost you something like $1 to $2+ per kWH -- Or around 10x what utility power costs (assuming 20 year system life, new batteries every 5-8 years, new electronics every 10+ years, some fuel for a backup genset, etc.). Makes it much easier to decide what appliances you want to keep vs ditch (i.e., electric vs propane fridge, etc.).

-Bill

Iceni John · March 2015

4 kW of PV power on a medium-size RV isn't going to happen! You need to visualize the actual space that the panels will use on the roof, allowing for them never being shaded by anything up there such as A/C shrouds or vents. On my 40' bus I have eight 255W grid-tie panels in two tiltable rows of four on either side of a walkway that stretches 26' between my two roof hatches - the panels occupy 22' of that length, leaving me space for some eventual water-heating panels as well. Without the walkway and by shoehorning on as many panels as I could, I would have space for a few more, but nowhere near 4kW. Realistically I think you'll be lucky to get much more than about 1 or 1.5 kW of panels on your RV's roof.

You mention having a cargo area for ten standard truck-size batteries. I think of 8D batteries as standard truck-size - they're 160 lbs each and about the footprint of 2-1/2 golfcart batteries. Is that what you mean? I would be gobsmacked if any RV could carry that much weight! If you mean Group 31 commercial batteries, they're about the same weight and footprint as a GC2. (I'm changing my starting batteries from two 8Ds to two Group 31s because I'm tired of lugging those damn things around when I need to move them. Their only benefit over Group 31s is a much greater Reserve Capacity, but I don't need that in sunny Southern California!) Assuming you have space for ten GC2s, that's about 1125Ah at 12V (but they would need a weird wiring pattern to connect that amount for a 12V system), or a theoretical 562Ah for a 24V system (but I have no clue how one would connect ten 6V batteries for that!). It would be more practical to have eight GC2s like I'll have, then you can easily wire them in series and parallel for either 12V or 24V. However, eight GC2s are about 900Ah at 12V, and if you want to charge them at about a 13% rate ( a good goal for an RV system that probably will rarely achieve that ideal rate) you'll need about 2000W of PV panels to do so. That much PV is more than any single charge controller can handle at 12V - I'm using two Morningstar TS-MPPT-60 for that reason as well as for redundancy (I like having backups and Plan Bs!). Even with this much installed PV power and batteries, I don't think I could run a typical energy-hungry RV roof A/C for very long. You should think about more efficient A/Cs such as mini-splits or even window units with high SEER ratings, then you'll be able to run one or maybe two from PV. Even that's stretching it, and you won't have much power left over for any other loads or if it's poor weather.

Making an RV self-sufficient for electrical power from the sun is a noble desire, but the reality of having suitable roof real estate, sufficient battery space and weight capacity, and space for everything else (charge controllers, inverters, emergency generator for those unsunny days, emergency charger for that generator, switches/fuses//circuit breakers, etc etc) will necessarily limit what is possible. No two RVs and no two people's needs are ever the same - only you can decide what is realistic and practical for you.

John

BB. · March 2015

Regarding batteries--Are they deep cycle type? Or standard truck/marine type batteries... This types do not like to be deep cycled and will generally not last as long when cycling below ~85% state of charge. Figure out how many batteries at what voltage and Amp*Hour rating you wish to install. We cannot guess at this--I try to design a "balanced" system. Loads drive battery bank size, Battery bank Size and Loads drive solar array size, how the panels are mounted and where the vehicle will be used (amount of sun) also drives array size.

A/C is a heavy load... If you use A/C a lot--That may be a "killer" for off grid solar power. Insulation/shading your windows, perhaps some low E window film (if they make it), etc.

And even looking at your present A/C system--Perhaps a very high efficiency mini-split or other system can help. But even if you come close to being able to generate ~4kWH per day--For a ~10,000 BTU system on low for ~10 hours per day would use all of the solar power you can generate from an on board power system.

thedogatemyhomework wrote: »

On shore power, electricity for this little truck can easily hit 300 per month running the air. 3600 per year. That seems silly to me.....my last apartment used less!!.

I don't know what the price of power is at your place--But lets call it $0.15 per kWH:

$300 per month / $0.15 per kWH = 2,000 kWH per month
2,000 kWH per month / 30 days per month = ~67 kWH per day
67 kWH per day / 5.6 kWH per day = 12 times bigger than what I think you can fit in your RV

If I am anywhere close to guessing your power usage correctly and what a solar system on your RV can produce, you would only produce a fraction of the power you are presently using every day.

It seems to me I am the prime candidate for solar; I have access to cheap batteries, cheap homemade solar panels (if 40 cents a watt is cheap?), I have cheap tempered glass sheets almost literally across the street, Installation wont cost me anything for the labor...if 3600 dollars is what I am going to spend this year, then the electric bill can just go away....and with my resources and access to discounted bits, I think it just may do-able.

Personally, I am not a fan of building your own panels. The cells you get off EBay and such, are many times rejects from solar companies. There are some process failures where cells can overheat when used in a solar panel and other issues--That is why they were rejected in the first place.

And if you can get panels warrantied for ~25 years for $1 to $1.50 a Watt with aluminum frames/wiring/etc. -- I just don't see making your own really worth the time and risk (panels that fail can be a fire hazard):

http://forum.solar-electric.com/forum/solar-electric-power-wind-power-balance-of-system/advanced-solar-electric-technical-forum/3375-panel-fire-question?4524-Panel-Fire-Question/page3=

I have no washer, no dryer; I do not use hair dryers or toasters or waffle irons. Just LED lights, AC, the desktop, and the occasional 12v drinking-water-pump.

The above can run on just 1 kWH per day... Using propane appliances can help save on your electrical needs.

Is your refrigerator vented directly outside, or into the RV (extra heat/moisture can drive up A/C costs.

200 sqft - 40 cents a watt - 13.468 Watts per sqft (Thanks for that info BB, very helpful!)....so 5.39 per foot by my calculator----so $1100.00 covers the top of the truck in blue silicon from bow to stern, yeah?

That 13.5 Watts per sqft... I just took an average 185 Watt solar panel and divided by its total sqft to get an estimate of how much solar you can fit on your space--You will have to size real panels to fit your space/racking/etc.

add 10 batteries and I am under $1500.00 still. 1500.00 more for inverters and charge controllers....what else is there? Am I missing something here? Could it be that I have my head in the clouds? If what you are saying is I can look forward to spending 36,000 a year on solar...that makes my estimate seem like dreams and fantasies!! What gives?

Let us not get too far ahead of ourselves... Understanding your loads here are critical. Again, I am still guessing here but an off grid system on your RV would provide something like 1/10th of your present power usage. And I am not sure you are looking at deep cycle batteries--Batteries are usually a "killer" for off grid power systems. Expensive, heavy, maintenance, last only a few years, etc.

Note, for large battery banks, generally you need 24 or 48 volt battery bank (to keep the current from getting too large during charging/discharging). A large 12 volt battery bank can be a nightmare to wire (lots of very heavy copper cable) and keep running well. Plus voltage drop for 12 volt systems is critical--You can only have ~0.5 volt drop in your wiring from battery bank to AC inverter, and less for the charge controller.

Just to be clear these (see link below) are the cells I am considering cobbling into panels. will these work?

I am not a fan of building your own panels for a large solar array... I you want to try and build a small panel and experiment. (10 to 100 watt)--Go ahead. Most people have difficulties getting panels sealed and built well enough to withstand a few weeks or months outside in the weather (sun, thermal cycling, etc.).

Have I underestimated something?

Your actual power usage... That sounds like it a a no-go based on your expectations of an off grid power system.

-Bill

AuricTech · March 2015

If you're in one of the more arid parts of Texas, an evaporative cooler (a.k.a. "swamp cooler"), such as the TurboKOOL, might help cool your RV. The tradeoff is that, while the TurboKOOL uses far less power than does a standard air conditioner, it uses a lot of water to operate.

Of course, if you're in a humid area such as Houston, evaporative coolers are pretty much useless.

thedogatemyhomework · March 2015

Thank you for the sage reply BB! Ok from the top...

Are they deep cycle type

Lead acid I believe, not deep cycle.

standard truck/marine type batteries... This types do not like to be deep cycled and will generally not last as long when cycling below ~85% state of charge

is cycling below 85% of charge something they are likely to do? Should I consider deep cycle batteries instead?

Figure out how many batteries at what voltage and Amp*Hour rating you wish to install. We cannot guess at this--I try to design a "balanced" system. Loads drive battery bank size, Battery bank Size and Loads drive solar array size, how the panels are mounted and where the vehicle will be used (amount of sun) also drives array size

Guesswork has no place here I agree. so what you are saying is that I need to figure out how much power I will use (LOAD), then try to balance the system to provide that much power?

A/C is a heavy load... If you use A/C a lot--That may be a "killer" for off grid solar power. Insulation/shading your windows, perhaps some low E window film (if they make it), etc.

Right, lets discuss that a moment. This entire truck has been rebuilt from cab to cabin, and when that happened the windows were all removed, cleaned, tinted and sealed before putting them back on. Every void inside every wall (what used to be filled with fiberglass batting) has been filled with expanded foam and covered in sound-brace structural sheeting on the inside, with a fiberglass GelKote finish. Every window has extra thick custom hand sewn "blackout drapes" which are constructed out of several layers of heavy denim.

Just the chill of an icy beverage in the truck can noticeably lower the air temp around it...as can a heated beverage raise it. This is not your typical RV leaking air from every corner. She is sealed up top and bottom tighter than a drum and I have spent a lot of time and money making her that way because this is Texas. Between March and October the temperature around here can reach 110+ and stay that way for weeks and the aluminum truck is basically an easy-bake oven during those times. I cannot sleep when its 105 degrees and I am sweating buckets. AC is not just a requirement, it is ESSENTIAL to avoid heat stroke around here!

If the AC only ran 10 minutes every hour, that would be plenty to cool off this truck and keep it more than comfortable at any hour. I imagine a world where the truck charges all day, and then the AC gets turned on when the sun sets to cool the truck in preparation for sleeping. If the batteries are dead the following morning from running the AC all night, then its a good thing the sun is about to rise again to start the new day...

I may be all wet. I dont know yet.

If I am anywhere close to guessing your power usage correctly and what a solar system on your RV can produce, you would only produce a fraction of the power you are presently using every day.

....Indeed. Part of that usage is the 12v transformer which pulls 110 and converts it...so there is heat and voltage lost that wont be there when solar becomes available running the 12v. My understanding of the 12v transformer is that it draws load whether it is powering something or not by virtue of the fact that it is plugged in at all. This must be true because it hums loudly and is warm to the touch. 24;7 When this goes, so does part of my load. I am also (inefficiently) converting 110 into 12v and 5v via a regulated power supply to run my desktop PC, but when solar comes, I plan on powering those directly (and efficiently) off the 12 volt too. Same for monitors. Another thing that uses power is the 100 feet of voltage dropping gently warmed shore-power cable and circuit wiring that is eating power just being a long wire with lots of resistance that wont be a factor when going solar. I suspect that these things may account for up to 30% of the load or more, as they all get quite warm.

I will check into replacing the factory installed Dometic heat pump roof unit with something more efficient. Can you suggest any other rooftop models?

Personally, I am not a fan of building your own panels.

That is unexpected, and a little disappointing I have to admit! I understand your reasons, but I do not believe I share them with you and I will tell you why... The idea of producing my own panels from scratch sounds like tremendous fun to me, and if doing so means I am forsaking a warranty with a company that probably wont be around in 10 years to honor it, I can imagine worse things. I fully expect them to sustain damage sometime in the next 10 years and require repair--but by that point I will be qualified to repair them myself and wont need a warranty. I will be completely familiar with their design and materials by that point and can repair or replace them myself. Self sufficiency in all things is my goal, and solar panel acquisition and maintenance are no exception.

Is your refrigerator vented directly outside, or into the RV

That depends entirely on the season. Being a source of heat is advantageous in the winter, so in the winter the outside vent gets closed while the cabinet vent gets opened to keep the heat in. In the summer, I reverse it and vent the extra heat out.

That 13.5 Watts per sqft... I just took an average 185 Watt solar panel and divided by its total sqft to get an estimate of how much solar you can fit on your space--You will have to size real panels to fit your space/racking/etc.That 13.5 Watts per sqft... I just took an average 185 Watt solar panel and divided by its total sqft to get an estimate of how much solar you can fit on your space--You will have to size real panels to fit your space/racking/etc.

Ahh, I see. Back to the calculator for me then...

Let us not get too far ahead of ourselves... Understanding your loads here are critical.

Agreed! How can we best determine loads? Shall I buy a Kill-A-Watt to measure it over several days? I could take readings directly from the meter base if thats better? I could also post the details from all the power rating placards from the AC and such along with a schedule of its usage...I am ready to determine loads. Just tell me how and I will do the very thing you instruct me to do.

Again, I am still guessing here but an off grid system on your RV would provide something like 1/10th of your present power usage

That wont necessarily make it a non-starter, it just makes it more important to examine it that much more closely. We dont actually know (hence the guessing) which is why finding out seems like the next step.

Have I underestimated something? Your actual power usage... That sounds like it a a no-go based on your expectations of an off grid power system.

Boy are you ever right on the money on that! I have no clue what this truck actually pulls, I have no idea what to expect, and I have no earthy notion how to go about figuring that out. I suspect that I can measure it, and if so I would rather measure than guesstimate. I suppose that measuring it will tell volumes,

So, if you dont mind me asking, how does one go about measuring such things?

Thank you for your help and your time BB!

Cheers!

BB. · March 2015

You can call me "Bill"--That is really my name.

thedogatemyhomework wrote: »

Lead acid I believe, not deep cycle.

Short answer is that Lead Acid batteries for cars/trucks/marine use are really designed to supply a lot of current for a short period of time. Discharging below ~85% state of charge.

Deep Cycle lead acid batteries should be cycled down to ~80% to 50% state of charge, with occasional usage below 50% sort of OK (and try to never go below 20% SoC--That can kill the batteries dead).

is cycling below 85% of charge something they are likely to do? Should I consider deep cycle batteries instead?

If you are off grid--ideally you plan for 25% of battery bank usage per day--Two days is 50% state of charge (state of discharge). Below 50% we try to keep as a buffer.

For mobile usage (RV/etc.). Sometimes you are forced to use upwards of 50% capacity per day--Just because weight/space requirements of the typical RV.

Guesswork has no place here I agree. so what you are saying is that I need to figure out how much power I will use (LOAD), then try to balance the system to provide that much power?

If read your meter once every 24 hours--That will give you the overall daily usage. And then you can go with (just starting suggestions--There are lots of options out there):

Kill-a-Watt type meter (120 VAC 15 amp plug in appliances)
The Energy Detective (120/240 VAC split phase--useful if you have 240 VAC/very large loads)
DC/AC Current Clamp DMM (this one from Sears is "good enough" for our needs). Use to measure current flow in wiring: Power = Volts * Current

A kill-a-watt meter is a great place to start--You can take some readings and do some math--Learn about how to account for your power, what appliances use a lot of power, etc.

Tuns out that small appliances that run 12+ hours per day (like a laptop) can use more power than big energy hungry devices that are only used a few minutes per day (microwave).

There are also secondary effects too... Large loads (microwave, well pump, etc.) may not use much power in a day, but you need a very large battery (and cabling/AC inverter) to support those short/high surge loads.

Right, lets discuss that a moment. This entire truck has been rebuilt from cab to cabin, and when that happened the windows were all removed, cleaned, tinted and sealed before putting them back on. Every void inside every wall (what used to be filled with fiberglass batting) has been filled with expanded foam and covered in sound-brace structural sheeting on the inside, with a fiberglass GelKote finish. Every window has extra thick custom hand sewn "blackout drapes" which are constructed out of several layers of heavy denim.

Sounds good--But that $300 per month is going "somewhere" (I have seen miswired electric meters--Loads from other tenants wired to the wrong meter, etc.)--So there may be some investigation needed on your side to ensure that the readings are "correct" and your equipment is running correctly.

Just the chill of an icy beverage in the truck can noticeably lower the air temp around it...as can a heated beverage raise it. This is not your typical RV leaking air from every corner. She is sealed up top and bottom tighter than a drum and I have spent a lot of time and money making her that way because this is Texas. Between March and October the temperature around here can reach 110+ and stay that way for weeks and the aluminum truck is basically an easy-bake oven during those times. I cannot sleep when its 105 degrees and I am sweating buckets. AC is not just a requirement, it is ESSENTIAL to avoid heat stroke around here!

And a very efficient A/C system--Perhaps only cooling your bedroom at night--Will help. But you cannot get the "help" that a building built on slab or earth berm type structure can give you (and the thermal mass of these types of materials).

If the AC only ran 10 minutes every hour, that would be plenty to cool off this truck and keep it more than comfortable at any hour. I imagine a world where the truck charges all day, and then the AC gets turned on when the sun sets to cool the truck in preparation for sleeping. If the batteries are dead the following morning from running the AC all night, then its a good thing the sun is about to rise again to start the new day...

I don't know--I don't have/need an A/C system. We have folks here living off grid with Mini-Split type systems that are very happy with them. However, they are not magic. Talk with an A/C supplier/installer, do some research to estimate your cooling needs, etc.

But you have some very difficult hurdles ahead here--If I guess somewhat close to your needs--You need to reduce your energy usage by 90%--That is not easy.

....Indeed. Part of that usage is the 12v transformer which pulls 110 and converts it...so there is heat and voltage lost that wont be there when solar becomes available running the 12v. My understanding of the 12v transformer is that it draws load whether it is powering something or not by virtue of the fact that it is plugged in at all. This must be true because it hums loudly and is warm to the touch. 24;7 When this goes, so does part of my load. I am also (inefficiently) converting 110 into 12v and 5v via a regulated power supply to run my desktop PC, but when solar comes, I plan on powering those directly (and efficiently) off the 12 volt too. Same for monitors. Another thing that uses power is the 100 feet of voltage dropping gently warmed shore-power cable and circuit wiring that is eating power just being a long wire with lots of resistance that wont be a factor when going solar. I suspect that these things may account for up to 30% of the load or more, as they all get quite warm.

Possibly--Just to give you an idea. 67kWH per day:

67,000 WH / 24 hours per day = 2.792 Watt average load 24 hours per day

That is like running ~2 portable electric heaters 24 hours per day... That energy has to be going somewhere.

I will check into replacing the factory installed Dometic heat pump roof unit with something more efficient. Can you suggest any other rooftop models?

Others can probably give you some good suggestions--But lets look at your present loads and kWH usage... Got to start somewhere and I don't want to see you put a much of money down a rat hole.

That is unexpected, and a little disappointing I have to admit! I understand your reasons, but I do not believe I share them with you and I will tell you why... The idea of producing my own panels from scratch sounds like tremendous fun to me, and if doing so means I am forsaking a warranty with a company that probably wont be around in 10 years to honor it, I can imagine worse things. I fully expect them to sustain damage sometime in the next 10 years and require repair--but by that point I will be qualified to repair them myself and wont need a warranty. I will be completely familiar with their design and materials by that point and can repair or replace them myself. Self sufficiency in all things is my goal, and solar panel acquisition and maintenance are no exception.

Not a problem--DIY solar thermal panels and wind turbines are, in my humble opinion where DIY can be better than commercial/or at least as good. Your choice, here are some links to some pretty professional looking DIY panels:

http://fieldlines.com/board/index.ph...,144982.0.html
http://fieldlines.com/board/index.ph...,144995.0.html
http://fieldlines.com/board/index.ph...,145004.0.html

That depends entirely on the season. Being a source of heat is advantageous in the winter, so in the winter the outside vent gets closed while the cabinet vent gets opened to keep the heat in. In the summer, I reverse it and vent the extra heat out.

Watch for Carbon Monoxide and humidity from combustion from the fridge--More than a few people have died from poorly vented/dirty burning refrigerators.

A Mini-Split Heat Pump system would be safer...

Agreed! How can we best determine loads? Shall I buy a Kill-A-Watt to measure it over several days? I could take readings directly from the meter base if thats better? I could also post the details from all the power rating placards from the AC and such along with a schedule of its usage...I am ready to determine loads. Just tell me how and I will do the very thing you instruct me to do.

The above links to various meters/equipment is a pretty low cost way to start.

-Bill

scrubjaysnest · March 2015

About battery weight, weight is always an issue in a RV. We tend to grossly overload them. This would be especially true for one as old as yours. Now if it isn't going to be on the highway ever then it won't be a problem.

Iceni John · March 2015

That is unexpected, and a little disappointing I have to admit! I understand your reasons, but I do not believe I share them with you and I will tell you why... The idea of producing my own panels from scratch sounds like tremendous fun to me, and if doing so means I am forsaking a warranty with a company that probably wont be around in 10 years to honor it, I can imagine worse things. I fully expect them to sustain damage sometime in the next 10 years and require repair--but by that point I will be qualified to repair them myself and wont need a warranty. I will be completely familiar with their design and materials by that point and can repair or replace them myself. Self sufficiency in all things is my goal, and solar panel acquisition and maintenance are no exception.

FYI, I bought my Sharp panels for $0.81/watt - new, UL listed, made in USA, and Sharp will be around for a LONG time. They're Grade Bs, which means they may have some slight cosmetic imperfections (some cells look slightly different to the others, big deal) and their output rating is to slightly wider tolerances than a Grade A. They have the same high quality of construction as a Grade A Sharp, same frame and glass, same cables, etc. It's hardly worth making your own when you can buy good ones for so little. After you price out aluminum for the frames, glass, backing, junction boxes, cables, MC4 connectors, solder, etc etc, I doubt you'll save anything at all. And I paid more than some folk do - I've heard of these Sharps going for about $0.70/watt from other vendors! Just make sure to get them locally so you won't need them trucked - that's what puts the cost up.

John

New rv solar from scratch

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