I need a "Solar Electric Mentor" this Summer 2021

Hi to all,

With so much infrastructure to build over the next five years (and perhaps beyond) I am seriously considering taking something like a Ford F250 and converting it to a solar/mobile electric station with generator, something versatile enough to take to a remote worksite with ability to connect and power a camper, an old house in the midst of deep rehab or just tools and technology in the backwoods.  The problem is, I have tried my hand at building a solar system previously and it was a spectacular crash and burn that resulted in my selling off parts of the project in frustration. I know how to do a few things, but electricity is a definite gap in my knowledge. In short, I am talentless. I was wondering if we could come up with a barter for the right person, mentor me and help me convert my truck to that power station, teaching both the practical and what theoretical knowledge my skull will hold.  My ultimate target is Alabama, however for this opportunity Id be somewhat flexible and perhaps camp out as long as necessary.  I have lived before in Virginia, SC, MS and Florida previously so Id say South of the Mason-Dixon and East of the Mississippi are my historical stompin' grounds.  Anywhere in that  neighborhood is fine.   Any takers?  Thanks for reading..... Best...M

I am far from your neck of the woods, but would be happy to offer you help remotely. I currently live off grid with solar and hydro power, and have been living like this for about 8 years now. If you are serious about learning, there are lots of great resources online, and learning how to find them would be a great place to start your education. The internet knows just about everything, but you do need to learn how to find what you are looking for in a vast sea of uneducated opinions and cat videos.

Anyway, designing what you are talking about should not be terribly hard. You will first need to quantify your goals. You need to establish how much power you need. Power over time is energy. You store energy; your applications require power (which is instantaneous) for as long as you wish to run them. So if you want to run one LED 800 lumen bulb that takes 10 watts for 5 hours a day, you will need to store 50 watt-hours. Add up all your loads, and you can start making an energy budget. 50 watt-hours for lights, 200 watt-hours for refrigeration, 50 watt-hours for pumping water, and so on. Once you have set your budget, then you size your batteries. If you have a lot of cloudy weather and you can not shift your loads around, then you need more capacity. One generally talks about the number of days of reserve - if you have enough power in your bank to carry your loads for 3 days, then you have 3 days of reserve. Then from there you size your array. You can look up solar-incidence maps to give you a ballpark number of sunny days in a given season, and estimate how much power you can expect to produce for a given size of array. There are limitations to how much charging current you can cram into a battery, so that should also be taken into account.

Once you have this outlined, you can start shopping for parts. I would guess that if you want to produce a couple of kilowatt-hours a day, you are probably looking at maybe 5000 bucks to get a basic system set up. An average household in the US uses something like 30kwh, so there are serious savings to be had by paring down your electrical needs....

Anyway, try and dig up some info on any of this that is not clear, and then feel free to fire away with more questions. Would be glad to help, if I can.

Thank you Carl,

-- that's very generous of you to offer your knowledge. I'm very grateful. As opposed to private moose-aging, I think others may be interested in the discussion so I will keep it public unless you think otherwise.  Okay. A process, great. So I already know that my general target is somewhat south of Huntsville, AL and Huntsville is listed as 199 days of sunshine a year.  So this is the first fork in the road where I find myself. Let's say, arbitrarily I select a long bed Chevy S10 truck or its equivalent a GMC Sonoma. I now its dimensions offhand and its possibly a good subject for this build.  Its extended bed version measures 58.4 inches wide x 89 inches in length. There is a roof and a hood which might nearly double the area mentioned if utilized.  Since all technology is a design compromise of some kind, my instinct would be simply to find the most efficient (within cost considerations) rigid panels to be had for the bed and flexible panels for the vehicle's roof and hood (if there are no prohibitions on a design like that.)  A quick look at a major supply house shows 200 watt x 12 volt panels which could be used for the bed, dimensions 64.5 x 24.5 inches.  With a bit of overhang, I then suggest that 3 panels in tandem cover the bed for a total of 600 amps x 12 volts .  One of my first questions would be, can and should flexible panels be mounted to the vehicle's roof and to the hood to increase solar panel area? Would engine heat degrade or reduce the efficiency of panels if they were mounted flush to the hood?  If so could/should they be mounted in a way to allow air flow beneath the panel for cooling effect?  I will stop here.   I'm approaching this in baby step fashion. Many thanks again for your wisdom on this project.   Best...M

PS I realized I haven't worked out any data regarding load, but that will take a little time.
PPS I assumed a rigid non moveable surface like a truck's bed cap, but it occurs to me that solar units might be stacked in layers with rollers to allow them to roll out of the tail gate, doubling or trebling the total panel area.
PPPS I just realized the tailgate might also mount a single panel, and when lowered would make for four rigid units in tandem.

Also needs to include losses going in and out.  Type of batteries, types of inverter, how you use the power all matter.  This can be as much as 50% but 20% is a good starting guess for a modern system.

As for the truck yes heat from the motor can degrade the cells.  Not saying it will make a serious difference in life but depends on how it is mounted etc.   But maybe look at how it is mounted.  In normal operation the panels can reach 140 to 160 degrees so how hot will they get on the truck hood.  Insulation, airflow etc all matter.  Also be aware that many of the flexible panels have limited life expectancy because they are coated in plastic and not under something more durable like glass.

How much mileage are you going to put on the truck?  Do you really need the hood or can you roof out over the hood a bit at roof level.  You can only go so far and still be able to see stoplights etc.  Can you stand the added drag and loss of fuel economy?  Or maybe build  a headache rack clear out over the hood like some plumbers and other construction people use and make the front panels removable to reduce drag.  Or what about panels that fold down over both sides of the camper that you fold up.

Now I am going to strongly second the notion of doing all you can to pare your power needs down.  Even with how cheap panels have gotten simply reducing needs will yield more bang for the buck than increasing supply.  Also how you use the power matters.  For example There may be a temptation to do solar to charge controller to storage battery to inverter to charger to tool battery sorts of things because it is easy.  Each step adds losses.  If you can set up to go solar to charge controller to tool battery you will be dealing with a more complex and expensive system for that part.  But you will save later even if it means doing something like doubling the number of tool batteries you carry with you for battery operated tools.

Finally for high load days are you willing to add a generator to the mix or is the goal purely solar?  Also what about charging your batteries while you commute?  Either by putting more load on the existing alternator or by adding a second alternator specifically for charging your battery bank while driving.

Or have your panels hinged so they pivot and safely stack themselves into the truck bed when not in use, somewhat like the hinges in the old tool box picture below.  There would still be enough space under those panels for a shielded, vented battery storage area and would keep those floppy, fragile panels secure and clean when not in use or during transit.

I am in Florida, when I started looking at EV conversions I  ran into this site which is not far from me.      You may want to give them a call just for ideas ->  

https://greenshedconversions.com

He has converted trucks a lawn tractor,     a regular tractor, and several other vehicles.


Mart

Thanks for that Mart! M

Hi C-

Thanks for all that. Now the 2nd alternator/generator is intriguing. I feel I should have known that. Its a great idea all in and of itself.  Where could I mount a second generator?

I am frugal so the truck would be my primary form of transportation, and also have distant future hopes that the S10 could make a great electric vehicle conversion if I ever had the money for it.

I did this schematic. Im struggling to find a design that would allow me to keep some free space in the back. I was looking at a dresser drawer with rollers this morning, why not the same setup for a second
panel of cells, one above the other?  Schematic attached.

Thanks for contributing on this.

Thats interesting too. What is that I'm looking at, a tool box? Thanks for contributing to this. M

Some questions du jour--

(1) If I'm looking at a system that may be using a hybrid source (generator plus solar panel) does this affect my choice of controller or is a controller a controller?  

(2) Does buying a controller rated for much higher than anticipated charges waste energy? Or is it just overbuilding?

(3)  Could a vertical axis wind turbine of a really short profile (like a pizza box for lack of a better descriptor) mounted to my cab's roof be an option?  Since the car is essentially an airfoil wouldnt 25 mph generate higher pressures than a straight 25 mph wind?  It would create drag on the vehicle and affect mileage, but if charging batteries is the primary goal, if the intake was even a half inch taller than the exit port, wouldnt air be compressed further and travel faster?  I have seen online some wind turbines projects made from relatively low profile ceiling fan motors.  Any thoughts?  M

Hey, I couldnt help but notice that you got a wire crossed somewhere in there - those panels are 200 Watts, not 200 Amps. To get Watts, you multiply Volts times Amps. So a 200 W panel at 12v would be 200/12 = 16.67Amps. (A panel that size that put out 200 Amps would be quite something, as it was likely producing more power than all the sunlight that was hitting it :)

So, some good points have been brought up. First off; about mounting panels. Solar panels need to be as close as 90 degrees to the incoming sunlight as possible to maximize their power. This means that bolting the panels in place in a flat orientation is not ideal. You will get more production from the same panels if they can be set to different angles, depending on the season and even time of day (or the direction that you park the truck). This makes me think that it maybe makes more sense to try and design a system around panels that are small and light enough that you can pull them out of the back of the truck and set them up on some sort of rack. Did you watch the movie "The Martian"? The panels will come with quick connectors, so they are not that hard to just plug together. You could even lean them up on a rail, with the bottom resting on the ground.

Also, about heat - I am not sure about longevity, but higher temps also reduce efficiency, so a little airflow under the panel is better than mounting them flat to a solid surface. I would skip the flexible stuff - its likely going to be more work than it is worth.

A heavy duty alternator is a great idea if you are going to go with a 12v system (there are advantages to other voltages, but 12v is a good place to start, and should be fine up to about 1000 watts of panels). Forget the wind mill. You will get much higher efficiency with an alternator driven from the engine, and it will be a lot less work to boot.

The charge controller only handles the solar power loads, so it would be completely separate from any other charging source. If you wanted to run a generator, you would need a battery charger that took the 120v AC from the generator and made it into the proper voltage to charge your batteries. An alternator has an internal voltage regulator, but it is only designed for lead-acid battery charging - but if you are on a budget, this is likely what you will have anyway. So, the alternator would basically turn your trucks engine into a generator (albeit not a very fuel efficient one).

With solar panels power is never wasted. The controller is basically monitoring the battery, and then feeding as much power to them as they want. Once the batteries are full, it thottles back how much power it applies. The solar panels only produce as much power as the controller requests. Buying a larger size just means that you can expand in the future, and also that you are less likely to overheat it if you run it full-bore all day in the blazing heat. A thing you will discover is that load-shifting is a good way to get more bang for your buck. If there are projects that require more electricity, you do them on sunnier days. If it is cloudy you lay low, or run down all your battery tools, and wait for a good time to charge them. You will note that they are rated in Amps. The reason for this is that current (amps) is what generates heat in wires. Any wire has a certain resistance, and the more amps you push the more "friction" this resistance causes. Remembering that Watts are Volts times Amps, we see that if we double the voltage, we halve the amps for a given array size in watts. You can always add more systems in parallel, or use bigger wires, but sometimes stepping up in voltage is the easier way to go. Again, it depends on how big you want to go.

Really though, 600 watts of panels in a sunny climate will produce quite a lot of power. If you figure 5 hours of good sun, that is 3000wh of energy. A single 18v 5ah battery holds 90 wh, so you could charge around 30 of those batteries (this does not account for losses, but will get you in the ballpark).

Thanks for that Carl,

Regarding angle to the sun, would it also work to fasten the panels to a cap for the back of the truck and use something like a pair of folding mylar lined wings on either side to concentrate and bounce the light?  My concern is that, if I need to park in some parking lot loose panels if a breakin occurred would be easier to walk away with.  There would need to be a cap to contain the panels and batteries anyway. If the panels were the cap itself, it would be one less thing to haul and they would still be in direct sunlight though at less than optimum angle in "parking/errand" mode.  ?

What about batteries? Ive read about deep cell, golf-cart type batteries.  If Im building up my system slowly, perhaps with monthly investments to expand panels and batteries is it better to go with some easily available ATV/RV batteries I could get nearly anywhere, or should I be persistent and try to find some surplus batteries over the internet somewhere?  

Do deep cell batteries need good ventilation like automotive batteries?  Are deep cell batteries sensitive to the kind of heat that might be generated in a locked storage in the back of a truck?

Thanks everybody, the project is coming to into focus (slowly.)

Finally, are solar components now all "plug and play" or will I need a good soldering iron for this?

Many thanks, M

Yeah, ultimately your design is going to be a compromise of many factors. If you put them flat, you will probably just have to figure that the panels are going to be derated. A quick search turned up something like 10 or 12% compared to an ideal angle (in a place at about 30 degrees latitude). The optimal angle can be approximated by the latitude. In the Southeast of the US, you would probably be looking at something similar. So really, a 200W panel would only be like 175W. But that is better than how much power they will produce if someone steals them, so its a good trade off. You might want to angle them slightly anyway so that water drains off and cleans the dust for you - so then you would just want to make sure you found a parking spot that let you face them the right way.

As for batteries and Heat, see this article - has lots of other good info in it too: https://www.trojanbattery.com/tech-support/battery-maintenance/

"FOR SOLAR APPLICATION

Store and operate your batteries in a cool, dry place.
For every 18° F (10° C) rise above room temperature (77° F or 25° C), battery life decreases by 50%."

So yes, keeping them in a baking hot locker is probably not going to do them any favors. That said, flooded deep cycle lead acid batteries are basically the same thing as a regular automotive batteries, which live in a hot steel box next to an engine. If you get flooded batteries, they will also off-gas hydrogen. AGM's dont, but they are more expensive, and probably not worth the extra money. Honestly, lead acid batteries are terrible, but they are cheap, readily available, and tolerant of a certain amount of abuse. I would suggest you start with them until you get a little more experience. I will also point out that lead acid batteries age pretty fast - so you really shouldn't mix old ones with new ones. Try and keep them within a year of one another would be my suggestion. Probably makes more sense to save up and buy the bank you need all at once.

As for connecting components; there will be no soldering required. A charge controller will generally have screw-terminals, sometimes on the outside, sometimes inside an enclosure with knock-outs for running conduit. You just strip the wires, insert, and then tighten them down with a screw. With low voltage stuff, you can get away with pretty sloppy work, and it will not be a hazard. Just make sure you fuse ANY positive wire that connects to your battery. There are charts you can look up that will tell you how many amps you can pull through a wire of a given size. For example, 12awg should have a 20A fuse. The panels are current limited, so if your panel is rated for 16.67 Amps, you can run it on 12awg wire and you dont need to worry about it - it would be impossible to overheat that wire. However, if you start paralleling panels, you will need bigger wire. Also, solar panels have a standard connector called an MC4. It has male and female plugs that click together and lock. You can buy splitters and couplers and loose fittings to make your own cables.

First what about moving the panels higher in the drawer motion.  Put the top of the stationary panel over the bed of the truck up on a rack that amounts to stake pockets and frame work so that panel is just level with the top of the cab.  Build a full rail set going out over the top of the cab and hood supported by posts off the bumper and roll the front panel out like a drawer.  In deployed mode the both panels sets would have full sun exposure.  In transport mode the panels would be stacked so only one set showed  Nothing would interfere with using the bed of the truck up to panel height and while driving you would have a couple of small posts up from the bumper carrying part of the weight and vibration of just the rails so if you moved your head a bit regularly to see around them the blind spots would be minimal.  In panel deployed mode it would look something like this.(see picture)

As for a second alternator the first thing I would do is see about adding a bigger existing alternator.  That would save rebuilding mounts etc.  Add a camper charge controller that protects the main battery from being drained by draw on the auxiliary battery.  The disadvantage here is you would be limited to a 12 volt aux battery.  A second alternator would let you have a completely independent voltage so you could do say 24V aux battery pack or 48V etc.  As for mounting a second something we have always found somewhere to mount one but I have always been bigger trucks and tractors.  More common for me is adding belt drive hydraulic pumps.  I have only ever added 2 alternators and both of those were on full size pickups.  Now I have done a number of belt drive hydraulic pumps and we have always found a hole and way to make the bracket and how to add pulleys to add another belt.  Some pickups you can add another pulley to the damper but usually it has to come off one of the accessory drives(say an alternator driven off an alternator or off the water pump and you have to watch out for the main serpentine belt slipping under load because of the added load.  Best is if it has a bunch of belts because adding is usually easier.

Now as for a generator you might want a standard gas generator so you can power anything assuming your generator is enough for.  Alternately you might was a gas motor driving an alternator with a voltage output that matches your battery bank.  Take it when you need it and leave it home when you don't.  Use it to recharge on cloudy days etc.  Say you got a 24V 150 amp alternator that is 3600 watts.  That is nearly 5 hp so you would probably need a 8 to10 hp engine to drive it.  Now if you go home every night you might not need it at all.  Simply charge the batteries off the grid at home or mostly at home and a bit more during the commute.   It literally depends on your needs and your goals.

Good information. Thanks, Mart!

Hi C interesting but would take the assistance of a welder for the frame, but Im not ruling anything out yet.

For a home construction or rehab project, if I was going to use a  gasoline generator as a standalone source of energy for my tools, what in your opinion is the recommended size?  Im mostly talking grinders, angle irons, recip saw, circular saw.   Being able to power a small welding machine would be a plus on the farm. Do I just go by the amperage of my most power hungry tool, say the welder and work backwards from that?

Many thanks, M

I'd go a slightly different route ... keep your truck bed free for truck duties, or perhaps even to camp in with a topper shell. Buy a HF 4'x4' or 4'x8' trailer kit, build it, and put everything you need for power stuff on it. It's easier to pull this stuff, than to cram it into a truck bed, which would leave you with reduced truck-bed capacity and capability.

The trailer would hold (now, or in the future) a gennie sized to your (jobsite) needs, all solar gear (inverter, batteries, panels, mppt, etc.), and so on. I'd start with the gennie, and add on as time and money permits, the battery bank and inverter, and finally, the solar panels and such.

You can build the HF trailer to your specs, because it's a kit ... you can park it at the job site, and provide power to the jobsite. You can take it camping, to get double duty out of it. You can lock up your tools and such ...

When you are on the road, extend a power cable with connectors from the truck to the trailer, and recharge the battery bank from your driving activities (the alternator part); this probably gets you more power than solar, unless you will be boondocked for long periods of time. If you can safely leave the trailer at the jobsite, then consider more solar panels, but the design of your trailer would better accommodate them than a truck bed or frame.

Thank you JT, there is alot to be said for a small trailer as a  solution and its definitely an idea in the running.

$1000 Solar Panel = 1000W (3x 333W), (with 4hr of sunlight per day aka 4kWH)
$500 Charge Controller = 1000W (80A*12V or 40A*24V or 20A*48V)
$2000 Battery = 4,000WH (LiFePO4 very compact and light, with 8000cycle)
$1000 Inverter = 4000W

Let me know what you think about the above and what you would like to revise or need some clarification on.

The advantage of solar panels is that they supply you with clean, renewable, and safe energy all the time. Standard solar panel found on most recreational vehicles ranges from 150W to 200W. It would be best if you inspected the watt rating of each solar panel and the total watts. In doing so, you could size the solar panel system precisely.  A panel might supply three percent more or three percent less power if it comes with a -3%/+3% power tolerance. Hence, obtaining the percentage number could remarkably assist you in computing the number of watts you will need every day more accurately.