Michael Qulek

Kathleen Sanderson wrote:We don't currently use any major solar, other than some small rechargeable items with built-in solar panels. I want to change that. My plan is to start putting up solar panels next year, then add batteries, inverter, charge controller. Then, as various appliances need to be replaced, I want to replace them with 12v. Eventually we should have the whole house running on solar, or close to it, leaving the grid wiring in place if we still need it for a few things (like the two window AC units that keep us cool in Kentucky summers).  

I would strongly admonish you to skip 12V, and graduate directly to 48V.  Did you know that at the dawn of the 20th century, 6V automotive electrical systems were the standard?  By the 1930's, everyone could see the limitations of 6V and starting moving to 12V.  By the 1950's, 12V was ubiquitous.  Today's new generation of electric vehicles are all 48V, and 48V will be the new standard of the future.  You might as well get on the new standard now.

I myself started out at 12V, and attempted to run my own homestead cabin on a 12V to 120VAC system.  It worked, sort of, but left a LOT to be desired.  Certain LARGE items, like the 240VAC well-pump absolutely could not run on a 12V system.  I graduated to 48V in 2017, got a dual 120/240VAC inverter, and have been powering my well-pump with that ever since.  My 48V system powers everything else effortlessly.  Running your power at higher voltage allows you to use thinner copper wire, which is obscenely expensive now.

All the 12V/24V DC appliances out there are overpriced niche products, and you end up spending less money overall going with a standard AC system, with mass-market appliances bought at your local store.

Don't start buying stuff until you've fleshed out a plan.  A lot of those "great deals" end up costing more in the long-run as you attempt to fit them into a system.  Put together a plan and we here can help you troubleshoot the design so you can have the best operating system.

Solar panels have become so cheap now that I personally when the whole-AC method, and went with standard AC appliances I bought at Home Depot.  With a 18cuft refrigerator/freezer, I find myself consuming about 0.8kWh in winter, and 1.8kWh in summer.  With 15 300W panels wired 3S5P, I can keep the batteries fully charged even in the rain on a December day.  Do NOT try to buy panels online from Amazon or Ebay.  Shop for local panels on Craigslist, and buy locally with cash and carry pricing.  I would ignore anything less than 3W/$ for brand-new uninstalled panels, and I think now 5W/$ is a good deal.  Bring a voltmeter with you if you are concerned about panel quality.  Don't buy anything with a Voc more than 10% less than the documented Voc pasted on the back of the panel.

I taught myself to weld a couple of years ago, mostly to build the array frames for our off-grid solar homestead.  I'd say that a smaller 120VAC MIG welder is the way to go.  If you select flux-core wire, shielding gas is NOT required for regular steel.  I got a Lincoln Electric 140A model, that I've used on-grid, off-grid, and powered via a generator.  If you do add a gas cylinder, it expends the materials weldable to stainless steel and aluminum, though I have yet to attempt welding either of those.

There is a learning curve, and the very, very first frames I build were of such low quality that welds cracked as I dropped the frames into place.  They did get better as time went by.  Have to say though by now my welds are starting to look professional, and I go out of my way to build/fix things by welding them.

I think it would be highly recommended that you outline that what you are creating is a carbon monoxide generator, and you must take the precautions required for working with a poisonous gas.  It's very important to understand that CO is an accumulative poison.

Sounds like your panels might be adequate.  What are their specs, and the specs of your panels?  Which Vitron charge controller did you get?

I myself am an proponent of rotating ground mounts, and I've constructed four different versions of them now for my various array frames.  Here are some pics.  The bulk of the materials are schedule 40 steel pipe, and half and full channel unistruts.

You don't mention anything about the solar resources used to charge this system.  That is going to be very important.  What's going to happen when winter storms blow in and you can't get sufficient charge for weeks at a time?  Will there be a backup generator?  I could envision your batteries being totally drained by day 7 of an extended storm?  Will there be periods of time you are away from the cabin, or will you be there 24/7 to tend to the system?

For my own 48V system,I started with 4500W of panels, in five arrays, all facing South.  I later upgraded the system with another 3000W facing due West to catch the late afternoon sun.  This was done to prolong the time I could keep my well-pump, and air-conditioner running in the late afternoon without any battery depletion.  The South-facing arrays start getting shading around 4:30pm or so, and are all in complete shade after 5:00pm.  With the Western arrays, I can keep the well-pump running till 6:00pm, and the air-con running till ~7:00pm, before the battery starts draining.

What's the reasoning for keeping the battery outside?  Is it the potential for a run-away battery fire?  If that's the concern, why build the enclosure right up against the wooden wall of the cabin, made with especially flammable materials?  If in fact the battery were to catch on fire, the outside wall would light after just a minute or two, and then work it's way up to the roof.

Since my battery bank is in an unheated North-facing utility room, I went with lead-acid Rolls-Surrette batteries.  After 5 years, they are still performing like new, with all twelve 4V batteries reaching full charge by the end of the day, even in the rain.  On a sunny day, ~ 10:00am.  The key for keeping lead-acid happy is abundant charging.  The legacy of the many, many, many dead off-grid systems comes from the chronic undercharging resulting from implementing too few watts of panel charging.

Nicolas Derome wrote:
So pawpaws are okay with the stems being covered in soils? I know some plants don't like that and it causes their stems to rot (happened once when I played peppers a little deeper than the cotyledons).

Since you have several deformed seedlings, try covering one deeper, and leave another as-is.  You can then determine for yourself if it's a problem.  In my personal experience though deeper stimulates roots.

I'm sorry, but why is this considered to be a solar myth?  Why does it need disproving?  Everyone in the solar community today knows about raising voltage to cross long distances.  I myself have recommended this in just about every solar conversation on this board.  Why is this guy acting like "he" discovered the secret?

Nobody has actually posted any kind of voltage drop calculator.  I use this one.

https://www.calculator.net/voltage-drop-calculator.html

For my own system, I'm running about 8A a total distance of 130 feet at 120VDC, with no measurable voltage drop through 10 gauge copper wire.  Just plug in your numbers into the calculator to see what you get.

I'd suggest that wiring 5-6 large 250W residential solar panels in series would give you between 150-180VDC that would cross that 200 foot distance with less than 2% voltage drop.

Of course, you need a charge controller (or AiO) that can handle voltage that high.

Remember though you are NOT measuring the working voltage making power, called the Vmp.  You need to be looking at the open-circuit voltage, which is what you measure when the array is disconnected from the controller.  That will be ~25% higher then the Vmp.  Also remember that the voltage of the panels goes up as the temperature goes down.  So, the panel Voc will be higher in below freezing winter weather then in summer.  You MUST take that into account when you are designing your system.  What are your winter lows like?

I think what you could do is to fill in the pots an inch or two deeper, and allow the curvy sections to produce roots.  Eventually, with roots forming above the curves, the curving will become irrelevent.