Micro Alternative & Renewable Energy

[JeepHammer]

*IF* I were doing a full on 'Survival' system...

Modular!
Be able to replace every part independently, and have spares!

Stand along inverter,
Stand alone charge controller,
Stand alone battery chargers/power supplies.

In combined systems,
The battery charger quits, the combined inverter/charger has to be disconnected, sent off for repairs, and that can take 6 weeks or more to get it back.

Charge controllers are cheap, some under $20, so you CAN have spares pretty cheap and just swap out the failed unit, back in production in 20 minutes.

Inverters are more expensive, but a pretty reliable inverter can be had for under $200 with no charger, and again fails can be changed in 20 minutes.

The biggest 'Fail' that can happen this way is a bad panel.
Depending on how you wire it, you can bypass a bad panel pretty easily,
But most times you will have to disconnect, test every panel, and replace or jump the bad panel.

Series (driving voltage up, keeping amperage down) is most efficient for inverters...
The issue here is a shaded panel (leaves stuck to panel, shaded during part of the day, etc) drags the entire string down to what the bad panel can pass through.

I hang a volt meter on my panel strings so I can check if voltage is low at a glance (if there isn't one built into the inverter).

Micro inverters & bypass control units (like controllers Solar Edge uses) keeps this from happening.
A controller behind each panel drives up cost, and there are more connections/failure points, but its a good idea in theory.
(Or you can just check on string outputs once in a while)

It's all in what you are trying to do, Im off grid, so I'm already set up stand alone.
If a guy wanted power in a SHTF situation, putting in a little parallel wiring would make a grid tied system a quick switch over to off grid, but most don't think about it ahead of time,
And when the SHTF comes, they can't browse the internet to find out how to do it.

 

[JeepHammer]

DC coupling,
That's ganging inverters to provide more power, most common (larger) inverters are 2,500 watts (2.5kW) up to about 6,000 watts (6 kW).

More and more inverters are designed to connect to provide split phase power.
That's TWO 120vac output inverters connected together to give the common household 240vac, split phase power.

This USED to be quite expensive,
You needed a combiner box, and you needed to add inverters in pairs to that combiner...

Now you can get inverters that connect together to produce 240vac/split phase power, and the inverters can be under $1,000 USD each.
(See inverters like Growatt, but this isn't the only brand that gangs together)

Now, I can recommend a balancer attached to your breaker box.
This will balance the 120vac input legs, and it allows you to do hard starts on larger electric motors (air compressors, water pumps, etc.),
And it also balances the loads in the home, moving power from one 120vac leg to the other, making your system a little more efficient.
They are REAL simple, 3 AC connections to the breaker box and an earth ground.

These are low consumption, often much less in losses than imbalanced loads in the breaker box.

 

[JeepHammer]

To dispell some myths,

Solar panels have about as much currently non-recycled metals (electrical traces) as a 'C' size disposable battery.
The aluminum frame, the glass/silicone is non-toxic and recyclable.
Only the very small electrical connections bonded onto the silicone layers are currently not recycled.

And most commercial panels have a 20 year lifespan while a 'C' cell battery lasts 20 minutes, get dumped into landfills by the billions every year.

I have panels that are 35 years old (or older) and still produce.
The production decreases about 1% per year, at 80% (20 years) they are considered at the end of their life span, but still produce just fine.
I use weak batteries & panels for electric fence chargers, security lights, etc.

--------------------

Current battery technology is somewhere between 4X and 50X charge density of lead/acid battery storage and/or lifespan.

*IF* you go lead/acid you will need a MINIMUM of 4X the number of batteries you *Think* you need...
Lead/Acid batteries are significantly damaged when discharged below 25% of full charge.
The deeper you discharge, the faster the battery damage accumulates...

Now, every current battery will damage itself when charged/discharged,
But current technology is allowing much less damage (and higher charge density) without significant damage.

Personal testing for LFP batteries is showing about 1-2% per year, but I'm running pretty big battery banks so I'm not discharging completely...
At the current rate, these batteries will be 80% efficient for 10-15 years, and still have plenty of storage capacity after that, but 80% is the benchmark most companies use for 'Failed' batteries.

When using lead/acid batteries the voltage drops off immediately and continues at a downward curve. At about 25% discharge the voltage has dropped off so much inverters will automatically shut down.

When using LFP batteries, they have a much flatter output voltage rate.
The voltage doesn't drop off significantly until the battery is 80% discharged.
That's 3-4 times as much useable energy return without damaging the battery...
Combine that with 4-5 times the lifespan of lead/acid batteries and the cost per watt hour is VERY good.

Some batteries are 'Hybrid', they work more like solid state capacitors than batteries.
These aren't common, where LFP batteries are, and they are currently very expensive per watt hour.
What makes this attractive is the lifespan, virtually unlimited so I'm waiting to see if I can get my hands on them.

While charge density in other chemistry batteries is higher (bigger returns on energy input) the LFP fail safely.
Some batteries fail with fire, meaning they burn when shorted out or punctured...
Safety is a concern of mine.

 

[kaveman]

Keep going,.....I just found this thread and I'm eating it up. This is very timely. I'm in the process of putting together a 'future' and I need the info you're putting out. I'm planning on going completely off-grid and have a barn full of panels so far and am sorting out the Growatt models and availability right now. If I follow through with my plan it'll be three tier,.....

A subterranean house on a small bluff overlooking a pipeline r-o-w that should make a nice 1/4ac garden. I want to build a passive solar greenhouse above the subterranean house as cover, moisture protection and to have a nice 12mo/yr 'outdoor' area. And I want to run the home and DC greenhouse fans(winter heat/summer cooling)with solar.

Like I said, I have more than enough panels to do anything(15kw+), several whole house gensets for backup power, I've accumulated a few dozen DC fans and blowers of various wattage and cfm to choose from,......and a couple large sheets of greenhouse poly just delivered today. I may be another yr trying to get started but I'm snagging component parts while they're readily available. I foresee shortages of most things over the next few yrs(or more). I want enough poly to see me through the next decade or two and all the component parts of my PV 'system'. Growatts are on backorder most places I've checked and with things slowing down in China along with all the shipping woes,......I think I want to decide on a unit now and grab one(or two).

 

[dprimm]

Look at watts247.com. Ian gives great USA support. I am not affiliated w him. He gets great reviews on the diy solar forum and has been very patient helping me quickly find a problem in my panel system.

 

[kaveman]

I've got his page open in another browser right now checking stock, specs and prices. He's up alongside Signature Solar(who I'm getting constant emails from ever since putting some panels in my cart to check shipping). Why is it that vendors are so hesitant to put their physical location anywhere on their website? It would be handy to know when you're thinking about shipping packages that weigh a ton.

 

[dprimm]

I've got his page open in another browser right now checking stock, specs and prices. He's up alongside Signature Solar(who I'm getting constant emails from ever since putting some panels in my cart to check shipping). Why is it that vendors are so hesitant to put their physical location anywhere on their website? It would be handy to know when you're thinking about shipping packages that weigh a ton.

Santan solar is either Az or Tx. Watts is Utah.

 

[kaveman]

Yes, I looked into those when I was shopping for used solar panels but everybody is a thousand miles or more away and shipping is a problem($$ and logistics). While scrubbing ebay I found someone in Michigan City just 4 1/2 miles away from me who was wholesaling out a truckload of panels so I trotted on down there with truck and trailer and took all I could afford(and carry). I knew better than to buy the panels before working out a plan,......but I did it anyway.

 

[JeepHammer]

Keep going,.....I just found this thread and I'm eating it up. This is very timely. I'm in the process of putting together a 'future' and I need the info you're putting out. I'm planning on going completely off-grid and have a barn full of panels so far and am sorting out the Growatt models and availability right now. If I follow through with my plan it'll be three tier,.....

A subterranean house on a small bluff overlooking a pipeline r-o-w that should make a nice 1/4ac garden. I want to build a passive solar greenhouse above the subterranean house as cover, moisture protection and to have a nice 12mo/yr 'outdoor' area. And I want to run the home and DC greenhouse fans(winter heat/summer cooling)with solar.

Like I said, I have more than enough panels to do anything(15kw+), several whole house gensets for backup power, I've accumulated a few dozen DC fans and blowers of various wattage and cfm to choose from,......and a couple large sheets of greenhouse poly just delivered today. I may be another yr trying to get started but I'm snagging component parts while they're readily available. I foresee shortages of most things over the next few yrs(or more). I want enough poly to see me through the next decade or two and all the component parts of my PV 'system'. Growatts are on backorder most places I've checked and with things slowing down in China along with all the shipping woes,......I think I want to decide on a unit now and grab one(or two).

You do what you think is best for your situation...

What I did was 8 feet into ground and 1/2 floor above with southern exposure.
Insulation is the foil backed type, works as a reflector down into the structure.

I used clear/opaque polycarbonate tube type sheeting for windows,
Not exactly clear, but much cheaper than glass.

Now, sun angle is a deal, so the windows are vertical, they face a low winter sun, and the back wall is foil to reflect light down.

I used air tubes, just black plastic drainage tubes out about 100 yards in trenches about 5 feet apart leading into the greenhouse.

This pre-heats or pre-cools the incoming air as needed, it's poor man's geo-thermal.
Since low consumption computer fans come in all sizes, you can draw in air from tubes if your top venting doesn't do the job.
Computer fans are cheap, reliable & low power consumption.
A simple tin block off plate shuts things down when you don't want the draft.

The opaque windows don't go all the way to the insulated part of the ceiling...
I did a short opaque panel just short of the roof line, this is a top vent for excess heat in summer time.
It simply tips out from under the roof line to vent.

There are no power greenhouse vents that operate thermally, they open when it gets too hot automatically, which means I don't have to monitor every minute on warm/hot days.

When it gets too hot, I simply use fabric (surplus parachutes) to shade the main windows.
Its a simple stick with cloth rolled around it, pulley & parachute cord to roll/unroll.
Let the automatic vents control maximum temperature.

I didn't worry about 'Water Proofing' in a greenhouse...
Since it's high humidity (gravel floor, drip watering plants) I just used as much rot proof materials as possible.

Its a foundation, concrete block walls, back filled with pea gravel (drainage & evaporation for humidity), treated wood, etc.
Any moisture that gets in is just water you don't have to pump or haul, or pay for...

You CAN use a large water tank, or water filled barrels painted black to absorb heat in the daytime and release at night.
I started with solar-thermal panel to heat water,
A solar electric panel to run a pump,
runs when the sun is out and warming, shuts down automatically at night to retain heat...
Heated a big tank of water I used for catch tank from plant watering, recycling my fertilizers...
Getting that tank of fertilizer is pretty easy to do, but will need cleaning once in a while.

I needed this heat harvesting in above ground greenhouse, but shut it down when I went earth sheltered, just didn't need it when it never drops below 55°F, even all last winter.

I considered fish in the tank.
Fish crap is second only to rabbit 'Tea' for liquid fertilizer.
Rabbit hutches in the greenhouse make it stink, but the rabbits provide CO2 for plants, body heat when it's cold, eat garden waste/grass that's not competition for human food, and produce great fertilizer, in the end, they are good protein meat.

There are a lot of ways to do this,
I go biological when I can...
Things like praying mantis & ladybugs will keep most insect pests out of your closed in spaces.
Cheap & VERY effective since they reproduce as long as there are pests to eat, and will actively hunt down every pest they eat in the enclosure (including eggs & larva).

 

[JeepHammer]

I don't discount anything outright, you never know what the situation will demand...

I'm using 100-120 year old sewing machines because they work with, or without electrical power and do a great job on basic sewing...
This includes the $20 a TON for surplus parachutes.

Parachutes make great netting/drapes for raised garden beds (posts in corners and along sides),
Good sun shades for windows when you don't want direct sunlight,
I've even made area slings up off the ground (with ratchet straps between trees) for kids to build 'Forts' from.
I keep them low to the ground because they are surplus, strength unknown, but they are VERY comfortable and the kids even like sleeping on them.
Another on top makes a big net to keep Indiana twin engine mosquitoes off the kids (and sometimes my wife!).

Early on I was hauling water, which is back breaking...
A post, pulley & rope made buckets on each end of the plant troughs (gutters) pass my fertilizer & water mix back & forth through the trough.
Reduces water hauling by 90% and retains the fertilizer for a couple of posts, pulleys, ropes and a couple 5 gallon buckets.

Gutters let me get my produce up off the ground, vertical gardening is a real space saver.
Under a parachute and off the ground keeps the birds & bugs off my strawberries (gutter berries!).
Works for about any bushing produce (since it doesn't climb).

Barrels work pretty well, just cut a about 5" slots in the side, heat the plastic up, and make a wedge out of a 2"x4" and expand the plastic outward.

I use a piece of drainage PVC pipe (about 4") down the center with a cap on top for watering & compost waste...
Fill with soil, plant in the pockets.

I had a potato barrel that grew so many potatoes I had a hard time getting them out!
One word of caution, paint a potato barrel black or your potatoes will sunburn...
Yup! I did that... Once...

Electrical energy isn't the only way to do things,
Sun energy, both heat & electric,
Geo-thermal, or more accurately thermal mass of dirt,
Like the pulley & bucket, gravity works both ways. Raise the bucket the water drains, lowered it collects the water/fertilizer.

I wouldn't use an electric motor & timer for this, too much equipment investment & maintenance.
Using a little electricity to rotate solar panels is worth the effort/investment/maintenance for the extra energy collected.
In the winter, solar electric panels will collect 15% to 25% more energy on short days.

In some of the out buildings I don't often use, I simply use eye bolts screwed into the wall, leave those self charging LED yard lights in the eye bolts.

Grab one when you go into dark spaces, they come on automatically, shut off automatically when they come back outside, and work as night/security lights when not indoors at night.
They do all this for about $5 each (if China starts delivering again...)

Something like an old truck axle works as rotation for your solar panels.
Stick one end in the ground (with concrete) and use the other end that has bearings to rotate your panel rack.

Something like a big truck axle, you simply unbolt the axle from the hub, turn it around and bolt it back on and for zero dollars you extend the depth of your rack anchor.

A couple spots of weld on the differential (or a bolt through the differential) and you can use the gear reduction in the gear set with an electric motor to rotate your panel rack to track the sun.
Smear some grease on the gears, on the bearings and you have a rotator that will last for decades without issues.
(Mine are approaching 25 years without maintenance and still working fine)

Its all in what you have and how your imagination works...
Mine works in mechanical terms, anything I see I try and figure out a way to repurpose it... Even plain dirt used as thermal mass.

 

[JeepHammer]

Yes, I looked into those when I was shopping for used solar panels but everybody is a thousand miles or more away and shipping is a problem($$ and logistics). While scrubbing ebay I found someone in Michigan City just 4 1/2 miles away from me who was wholesaling out a truckload of panels so I trotted on down there with truck and trailer and took all I could afford(and carry). I knew better than to buy the panels before working out a plan,......but I did it anyway.

I started with used, and mismatched panels.
I have no idea if yours are mismatched...

The only way to use mismatched panels together is parallel, build amperage at whatever the nominal voltage is.
That means a lot of fat wire to handle amperage, and inefficient inverters that work at low voltage.

If the panels are matched, then series so you can drive voltage up, keep amperage down.
More efficient to convert through the inverter.

Yup! I made every mistake at least 3 times since I'm thick headed and often have to make my own mistakes...

I bought out a commercial contractor bankruptcy just before the COVID thing hit and wound up with WAY more than I bargained for, but I wasn't going to let it go to the dump.

When you put a new 300 watt panel where a 20 year old used 80 watt panel was, it doesn't take long before you need to rewire for the increased capacity.
It feels pretty good to have surplus power, and now I'm looking into EVs to use more of that excess...

 

[kaveman]

I've kept my panels matched. First pallet I bought contained 25 240W panels all the same. I didn't know any better at the time and they turned out to be 60 cell 20v panels which are fine but not ideal for battery storage. Later when I looked to see about buying a few more I found that he was out of the 20v panels but had just received a truckload of 72 cell 24v 290W panels,....and when he quoted me the exact same price I'd paid for the previous panels I showed up at his door with truck and trailer,....and cash. Bought two pallets(50 panels)of the 290W and have relegated the 20v panels to thermal storage. Plan on using about half of the 290W on 'my' electrical system and holding the second half back in case my sister needs power.

Sorting through the Growatts now,......settling on a voltage(even though I don't have batteries yet). I like 24v but suspect that I'd be better off with 48v battery bank.

Looking at this,.....

Growatt 24V 6kW Split Phase 120V/240V Package 2 x 2kW MPPT (2 x SPF 3000TL) – Black Friday – Watts247.com

watts247.com

Like the redundancy of twin units but the max solar input seems too small and don't like the max input voltage.

This is better. Same system at 48v, same price but MUCH better solar input(still at a low voltage though).

Growatt 48V 6kW Split Phase 120V/240V Package 2 x 4500W MPPT (2 x SPF 3000TL) – ships now – Special – Watts247.com

watts247.com

And then there's this setup,.....

5kW ES & Transformer Kit

DESCRIPTION SPECS & MANUAL VIDEOS SHIPPING 5000W LVM- ES Off-Grid 240V Growatt Inverter with Solar Charge Controller + Solar Edge SEAUTO-TX-5000 Mid-Point Transformer for true 120V/240V Split Phase Electricity! The Growatt SPF 5000W LVM-ES is the all-in-one inverter/charger you need to take...

shop.signaturesolar.us

Single unit w/transformer to get split phase 120/240. A little cheaper for the system, a little less output(5kw/10kw surge)and solar input splits the difference at 6kw but the input voltage is up where I want it. While the others are available it looks like there may be a 4-6wk wait for this system,.....and I don't trust that the world will still be the same in 4-6wks.

Still a lot to figure out and I feel like I've started way late.

 

[JeepHammer]

Yes, I looked into those when I was shopping for used solar panels but everybody is a thousand miles or more away and shipping is a problem($$ and logistics). While scrubbing ebay I found someone in Michigan City just 4 1/2 miles away from me who was wholesaling out a truckload of panels so I trotted on down there with truck and trailer and took all I could afford(and carry). I knew better than to buy the panels before working out a plan,......but I did it anyway.

The rule of thumb currently is $1/watt for common commercial grade panels.
A little more for the super output versions, a little less for older designs that put out a little less for the sq.ft.

If you are on a shoestring budget, the only way used panels make sense is if you get them from government buildings when administrations change.

I scrounged panels from all over the place for more than 20 years, so I have experience...

Republicans rip off 4-8 year old panels, sold at salvage auctions.
When the Democrats get back in, new panels go back on... The taxpayer gets the bill for installation & removal in both cases.

Where you will REALLY get some value is solar thermal, hot water (or antifreeze) in glass tubes.
No condensation in the tubes means no vacuum leaks, and heating water is a HUGE energy hog!
I use radiant floor heating in the home and I can tell you most times we don't run the boiler, the evacuated panels are enough.
Just fill energy when the sky stays overcast, which usually isn't very long (relatively speaking).

I can give this one away,
I used to watch the county highway & state highway auctions.
They have road signs on little trailers, each one has solar panels, charge controller, batteries in a matched set.
When these things get dinged up, they get sold at auction, and for cheap.
A little straightening/welding and I resell the 'Utility' trailers, keep the solar hardware.

 

[JeepHammer]

Mono-crystalline,
Usually black panels and usually small cells ganged together.
These lasted longer for me, and they resist shading losses better (it's the way they are often wired internally).

While the rated output is a little smaller for the size, they last the 20 years of the warranty (80% of rated power at the 20 year mark).

Poly-crystalline,
That 'Purple' or 'Blue' color so many advertisements show.
They usually drop below the 80% rated output faster, kind of lighten up, change color over time, and I had delamination issues with them, the glass seal separates from the silicone material and moisture/corrosion gets started.

They are higher rated most times (per sq.ft.) so they *seem* like a good deal, but my luck wasn't so good with them.

They usually aren't 'Half Cell' design, so they don't handle shading very well (unless things have changed since I bought them last).

Since one cell produces current,
Then passes that current to the next cell which adds to the current, and so on...
Shade just one cell and the entire panel output drops.
Output has to start over from the shaded cell, and the panel can only produce what the shaded cell will pass through.

In case you aren't a country kid,
Mulberry season is the worst for me.
The birds eat mulberries and land on my panels, then have the runs...
The bird crap shades the panels and production drops...

Mulberries are why I installed drip watering lines across the tops of my panels...
A little drizzle of water from the garden faucet and a long handle mop is the only way I know to deal with bird droppings.
Makes dust/dirt issues easier to remove also.
Since these are mostly summertime issues, a garden hose solves the problem,
In winter I just dust mop the panels once in a while.
There is usually more precipitation in fall/winter/spring, so I rarely drag the garden hose out.

...........

Another mistake I made you could potentially learn from,

DO NOT USE HARSH CLEANERS!

That stuff runs down the glass, stands on the seal/edge of the glass,
AND ATTACKS THE SEAL BETWEEN GLASS & PV SURFACE!

When the seal gets eaten away, moisture enters the lamination and the panel clouds, electrical traces get corroded away!

I used some of that 'Organic' orange peel based cleaner and lost panels in doing so... It's acid and it ate the seal, electrical traces in no time!

A little squirt of dishwashing soap on the cleaning mop saves your panels and works just fine...

My mop is actually a gym floor dust mop, wide and relatively light weight, and the head comes off to dry really easily.

Like a lot of things, the correct tools make the job MUCH easier!

............

Now, there is a way to bypass a crippled panel and restore almost full output from the other other panels...
Its called a 'Bypass Diode'.

Some panels are equipped from the factory, some are not.
At 10¢ to 50¢ per panel when you install, it's quite the deal!

A bypass diode let's higher current jump the crippled panel and move on down the line, it will cost you about 1 volt maximum, less with a slightly more expensive (lower resistance) diode.

Diodes picked at the correct amperage threshold actually work like a second fuse in the system just in case things go REALLY bad (like a lightening strike).
I'd MUCH rather replace a 10¢-50¢ diode, and a 10¢ to $10 fuse than a panel in the worst case scenario...
But then again, I'm a stickler for safety.

If you have any interest in a bypass diode I have graphics somewhere I drew for RE classes so the new folks could get a grip on what they do,
Let me know and I'll try to dig them up for you guys.
Since they are my copyright, I can't post them in the open forum, so we will have to do email or something...

 

[JeepHammer]

Mounting mistakes!
I made them all at least 3 times!

Surface level ground mount,
Grass/weeds grow up right in front, or between panels and shade them.

My old farm dog found out the panels were warm in the morning and slept on them...

The lawn mower throws rocks & debris on the panels...

Best way I found is above head level so you can mow under them, but not so high you can't clean the panels with a mop or duster.

They make a good car port, chicken run, etc underneath if you have the pace for elevated ground mount.
I use long fence posts and my pasture fence lines produce power...
I'm digging the hole anyway, and the pipe from a chain link fence top will hold the panels most time...

North/south fence line allows that pipe to rotate, track sun east/west which increases production 15%-25%.
Higher production means less panels, which is less total cost.

A gear reduction motor on a timer rotates panel pipe, so it's a pretty easy install if you are handy with basic tools.

............

When I started, it was a ground level rack that was WAY over built.
When I built the house, I needed to pull the rack and move it...

Now I'm off grid, all construction power was solar or generator.
I cut the rack off at ground level and put it on an old house trailer frame so it would work while construction happened.

I found out by rotating the trailer east/west to follow the sun, and I was there all day when building,
The power output was 15%-25% higher.

Plan 'B' was a big truck axle stuck one end down in concrete, the trailer mounted on the bearings/flange sticking up.
This gave me bearings to rotate the panels for sun tracking...

Later on, the gear set got a little welding and a motor was attached to the pinion gear, timers moved the panels automatically.

It was crude at first, and this took me about 5 years to figure out...
Sit and watch things long enough and an idea will come to you.

Now I just use tall fence posts or 4"x6" posts in a north/south orientation,
Use a pipe through the posts north/south,
Mount the panels on the pipe.
When the pipe is rotated the panels move east/west.
See about any commercial solar field...

Now mine is far enough up off the ground to avoid grass/weeds, and I can mow under them without throwing rocks at the panels.

Also, with a wind indicator, I can flatten the panels (straight horizontal) in high winds so my panels don't fold up in storms.
I *Can* rotate the panels face down in the event of hail, but to be really effective I'd have to use a backer behind the panel.
Hail can crack from the back as well as the front, and I have to be home to do the face down thing, override the normal timer positions...
So while a 'Good Idea' I don't have the details worked out yet.

The daytime movements are simple micro switches and cheap timers off eBay.
Reach the last timer and an extra switch reverses polarity and returns the panels for morning sun, and starts the timer running again, not much to it...

Some people have an actual photo eye sun tracker, but around here sunrise is more of less in the same position, noon is noon, afternoon is afternoon,
I reset the timer by season, about every 3 months, and just let it run.
On a pipe, flat panels don't compensate for elevation, so it's about timing...


............

There are VERY specific rules for home roof installation,
One of them is the 2017 electrical code change for rapid shutdown.
The idea is, you don't electrocute firefighters.

Some places require specific racks for the panels, so building your own out of what's at hand is out there.
Check your local code requirements before you do something that will cost you more money/work...

 

[kaveman]

The price of new panels has come down so much that I wasn't sure about the used panels, but from a 'quantity' perspective it makes a lot of sense. I got five times as much power as I could have afforded otherwise. These panels worked out to 16.5 cents/watt and even taking into account the degradation of a 5-year old panel it's still well under $0.20/w. It's still working out at 20 cents a watt at 80% rated power so I think I'll still be getting my money's worth thirty yrs from now.

So instead of having $3600 tied up in a single 3.6kw array I have enough panels to build 4-5 or those arrays. That gives me one or two to play with and one or two to set aside for someone else,.....and some spares. So if a twister does come through,...or a fire,...or a thief,....I still have options. And since they were used panels obtained locally there was no shipping or tax and for the quantity that saved me about a grand.

I'm still looking at all the options for maximizing the panels such as tracking and seasonal tilt but I'm not sure any of it is worth the cost/effort. From the tables I've been able to check, it looks like you might be able to squeeze out an additional 10% with seasonal tilt. Best options in my neck of the woods is to tilt at 48 degrees for best yearly power production or build a rack that allows 30/45/60 degree sets. If you go out and adjust the array four times a yr you can boost power by about 10%, but I can do the same thing by simply adding two panels to a twenty panel array. Cost is $100 and I don't have to move or engineer anything. Solar tracking can certainly get you more return but the cost and complication to do so seems excessive. Rather that movable supports, gears and timers(and power), just add 4 panels($200)to your twenty panel array and be done with it.

I think there's a lot of fun to be had dreaming up different engineering ideas to maximize the captured power but at present panel cost none of it is economically viable anymore. Panels are just TOO cheap. Things were different when watts cost you $5-7 apiece. I've thought of all sorts of 'manual' tracking systems with no automation(mostly trailer mount like you mentioned or pivot mounts on wheels(or even floats)). The idea is to have the array hand swingable from morning through afternoon. On days when you have the inclination you can maximize AM and PM power. On days you don't feel like doing anything you're no worse off than with a 'set' array. But it's still a complication in the array construction and harder to do than just adding a couple of cheap panels. What I do think is worth the effort is to construct a set 'V' shaped array with half the panels facing SE and half SW. One limitation to any system is the max wattage being pumped into the system by the panels. If you've got a south facing array and max system input of 5kw you can't build the array above 5kw and you'll only get that power for a short while mid-day. If you build an 8kw array with half the panels facing SE and half facing SW you'll get that 5kw for many more hours during the day. You'd have to figure your angles pretty close and maybe shade one string during summer to get maximum power during the winter, but that would be easy enough to do.

I really like your truck axle idea. That's clever and I think I'd look into doing that if I ever became short of panels and needed to boost the power.

 

[kaveman]

Cheap panel economics works its way into the PV vs Thermal too. My readings tell me that thermal capture is something like three times as efficient as PV electrical, but thermal evacuated tubes or any type of solar collector is way more than three times as expensive as PV panels,...so again, the simple solution is to throw more PV panels at the project. David Pos has a series of videos out on youtube where he direct compares a thermal panel to a string of PV panels for water heating. I think he's comparing equal cost vs cost but it might actually be equal square footage vs square footage. Whatever his comparison was, the result was that the thermal would win if space was a factor but PV panels easily win on a cost basis. And that's what I'm looking to do with my pallet of 20v panels,....just use them for thermal storage. A thermal storage system can be nothing but a tank of water with some heating elements installed(like your backup system for your boiler). Those elements can be run directly from the PV panels with nothing but wire,.....no controllers. no batteries, no electronics at all. Simple, simple, simple,.....and cheap. Just some panels, a few heating elements and enough wire to connect them. Then some method of distributing the stored heat from the well insulated tank(maybe underground in the greenhouse?). Radiant floor of the house? Lots of ways to use the stored heat and if all it takes is a $1000 PV array to make it,.....?

 

[JeepHammer]

I did about everything (wrong) about 3 times, trial & error... Lots of monitoring and note taking.
Its MUCH cheaper when you do it ONCE!

AC coupled, DC coupled, hybrid, off grid, on grid, solar electric vs solar thermal,
It's a steep learning curve sometimes.

I got my evacuated tubes (vacuum) used, for cheap at an auction and couldn't be happier with them.
Took a few tries to get things functioning correctly, had to learn the difference in piping/plumbing for oxygenated/non-oxygenated, etc.

Even overcast days the solar thermal harvests a lot of heat, which surprised me and made for design changes, but I'm a tinkering type, so it's all good.

Tubes ARE expensive, but they don't have an expiration date like panels do...
As long as you don't break them they just keep producing.
You do have to change end (liquid) seals every once in a while, 'O' ring gaskets, about every 20 years.
I use copper instead of synthetics, a little more tricky to install, but it will live 50+ years.
Darned little maintenance too.

Just keep them close to the house/use point so the piping/insulation doesn't drive the price up too much.

You are correct about efficiency,
A watt is 3.41 BTU of heat and it's 100% efficient using electrical resistance.

The issue is switching & control systems, line losses, and if you heat with battery power, battery charging/discharging losses and use damage of batteries.

Batteries ARE MORE expensive!
Beating up batteries to make heat is costly in the long run, no matter how efficient the conversion rate is at the water tank (resistance heating).

500-600 gallon cistern tanks are MUCH cheaper than batteries, or panels to heat water.
Insulate the crap out of that tank, coiled tubing for heat exchanger (stainless for hard water) and it's MUCH cheaper to do solar thermal.

The efficiency of radiant floor heat is impressive, since heated air rises.
Momma likes warm floors, so does the mutt, and I have to admit, as I get older so do I.
Knowing I'll never have to change the heat exchanger tubes in the floor also gives me a warm feeling, that's one part I'll never have to do again.

The two valves behind the front door are handy...
I put the extra tubing under the patio, open valves and the snow/ice melts off.
Costs me about $5 in propane, $0 with solar and I don't have to shovel!
BIG WIN there!
Stole that idea from a hotel construction site. I know a good idea when I steal it.

For panel tilt, a pipe at the top,
Muffler hose clamps mounting panel to pipe.
The pipe is your hinge.

At the bottom there is a pipe,
Use a spiral cut 'Cam' to push the bottom of the panel out.

This requires two things,
One is limiting straps from bottom pipe to panel so the wind doesn't lift panels way up and let them slam back down...

And the small part of your cam is low winter sun angle, as the cam pushes the bottom of the panel out, it reaches high summer sun angle.

When you are trying to determine season (by month, quarter, season or whatever),
Stick a plunger to the panel, when the handle shadow disappears you are aimed at the sun (at noon).
Easiest/cheapest way to determine the correct sun angle (90° to panel) I've ever found.

File/grind your cam for sun angle and you only have to pull the plunger out a few times...

I also use a metal protractor mounted to the panel edge,
A bolt/screw at the angle finder center,
And a hanging wire (plumb line) to show angle for those that want to know exactly what the angle is.

Protractors are cheap, screw & wire are about free, plungers are cheap,
And make your first cams out of wood so they are cheap.
Switch to metal or synthetic cams once you know exactly where your stops need to be.
Pipes are usually from chain link fence construction around here, but about any kind of metal pipes work fine...

The one thing I won't compromise on,
Earth Grounding.
Stainless steel panel clamps, minimum of 10 AWG ground wire, and at least 8 foot copper clad ground rods about every 30 feet.
Lightening is the one thing that can take out everything, so I do my best to see that doesn't happen...

 

[JeepHammer]

And I agree 100% on CHEAP when possible!

Most folks think because it didn't cost a fortune it's not worth having...
(Consumer Economy Thinking)

I struggled since 1997 with what ever I could scrounge up, but it all did the job!
It worked FOR ME instead of me working for it...

I'm SO HAPPY I don't have to scrounge used batteries, used panels, watch the charge gauge constantly...
But it was a LONG TIME getting here!

I do build my own batteries from cells, and I do build my own mounts, racks, rotation devices, everything but the inverters & panels.

I even built the welder that I build the cell packs with...

Its a REAL money saver, and I know EXACTLY how it's all built, how it all works, so repair/maintaince is a snap.

I do some RE and homestead classes, show people how to build/rebuild their stuff, and hopefully avoid my mistakes!
(I'm REAL GOOD at mistakes! )

The other side of that coin is,
Those NOT making mistakes aren't doing anything at all...

I'm determined to grow an orange in Indiana, the reason for earth sheltered greenhouse!
This is my retirement objective instead of bingo or pickling my liver.

It might not mean anything to anyone else, but if I can efficiently grow an orange in Indiana, it proves you can grow about anything in Indiana.

 

[kaveman]

I have no doubt you can grow an orange in your part of IN. There's a guy been growing citrus in Nebraska for 25yrs and all he's doing is low grade geo without any heat storage and no berming. If you store the excess daytime heat in the ground and have any insulation at all you can keep a greenhouse shirtsleeve warm all winter.

I'm up north just about eight miles from the shore of Lake Michigan and that lake gives us an unusual number of cloudy days. That's my only concern. We'd probably have 20% more annual sun twenty miles further south,......and not half as much snow.