JeepHammer
Solar Wizard
- Joined
- Nov 15, 2019
- Messages
- 1,149
Without starting a giant crap fight, this is MY EXPERENCE, and not up for debate...
Disclaimer end.
I started over 30 years ago off grid because I had to, no power supply to my property.
I've been through crappy panels, lead/acid batteries, etc, now operate a Mini-grid that powers homes, farm, businesses with little to no thought about consumption.
Lessons I've learned...
Get away from lead/acid as quick as you can. I had a business that sold lead/acid, talked with factory engineers, saw them produced, learned the difference between consumer and insustral grade, learned the difference between starting, pseudo deep cycle and actual deep cycle.
It's the chemestry, a liquid electrolyte battery is CHEMICAL storage, from the time the acid based electrolyte hits the plates, the clock is ticking on it's expiration date. Period.
Even at 100% State Of Charge (SOC) the battery is eating itself, literally. Below 100% SOC the clock speeds up...
The facts on charge density, usage between Lithium and lead/acid are well known and well published, so do that Google search...
The BIGGEST reason I went Lithium (LiFePO4 in particular) is longevity. They literally last 100X or more longer. This makes them WAY cheaper in the long run for the amount of kWh of work they get done.
Lithium-Ion is lower life span, but more charge dense. Meaning you get more power out of the weight/size. They are NOT the longest life, number of charge cycles.
LiFePO4 is less charge dense, takes up a little more space, but has 10x minimum the number of charge cycle life.
These batteries will sit for years on the shelf, not significantly degrade, and work fine. This is money in the bank for you.
Considering Lithium gives 4 to 10 times the returned energy over the capacity of lead/acid, again, Lithium the clear choice.
Now, this is the part that OFF GRID system owners should think about... Capacity is VERY high, well over the usable energy of lead/acid by 4 to 10 times.
You don't have to have the panels to make the power to recharge lead/acid every day from whatever sunlight you might get.
When you have 4 to 10 days worth of usable power in the same space/weight, you can have no-sun days, still have power, and the batteries can recharge/recover to 100% SOC over DAYS.
These batteries do NOT degrade quickly when at 25% SOC, or 50% SOC, so you can use that in your favor. No blast charging with a crap load of panels & high powered chargers trying desperately to get lead/acid back up to 100% SOC in a few hours...
the closer you get to 100% SOC with lead/acid, the higher the internal resistance gets, that WASTES a lot of the panel power. Losses in the system.
Again, you can charge Lithium with much lower input from the panels simply because the battery accepts the power without converting a large portion into resistance (heat).
In 2010 I got hold of Lithium batteries, several chemestries by coincidence. Started learning and testing, building my own batteries. In 2020 I upgraded a crap load of my up to 30 year old panels and found d between the efficiency of the batteries, using charge controllers specifically designed for the Lithium chemestry, and the Lithium batteries I was getting MUCH more power returned, needed many less panels/total Wattage, and had an embarrassingly large amount of reserve time...
Embarrassingly large because I'd been adding Lithium replacements for lead/acid for 10 years, but doing it on a 1:1 RATED Ah swap. I had about 7 times the useable Ah capacity, and I simply didn't need to have as many panels as I bought since they didn't degrade faster at below 100% SOC.
25 years watching every single Watt had broke my brain, I was stuck in that run believing I needed enough panels to charge lead/acid in 4 to 5.5 peak sun hours... with little or no reserve left in the batteries.
My recommendations are STAY MODULAR! No propritary, all in one systems that lock you into a particular manufacturer. As battery chemestry changes, you can switch to a charge controller that is optimum for the battery chemestry/type/size without changing rhe entire combined unit.
YOU get to pick a reasonable sized inverter that fits your needs. It will often be so inexpensive you can buy a backup, wire the back up in parallel, and flip a switch should one fail and be right back on line, and STILL SPEND LESS.
Off grid, reserve and redundancy matter. Batteries on a DC Buss means you can expand as necessity requires. DC transfer switches are cheap, separate charge controllers are cheap. Inverters can be cheap, so you can often double up and still spend less while getting redundancy.
My panels are on strings, each string has a charge controller. Charge controllers are in parallel. Same amount of Watts/Amps being dumped into the batteries (plural, again, redundancy) and if any one charge controller fails, it's literally flipping a switch to the back-up to get the panel string back on line. I can change the failed charge controller at my leisure, see what the updated unit is for my battery chemestry, and replace with the best unit for my budget and/or the job.
MPPT being built into almost every charge controller, and the technology getting better all the time I don't worry much about updating since these do fail from time to time, so it's an automatic update when something does fail.
It's a CHEAP update, not an $8,000 all in one combined unit replacment.
Expansion.
Almost everyone off grid decides to expand. Again, stay modular. Add panel strings, charge controllers, batteries, inverters as needed. MOST of the larger inverters today will 'Combine', the proper term is 'Gang' together. 2 each $750 ($1,500 total) or even 3 each ganged together beats replacing an $8,000 all in one combined unit.
Off grid youboften have SPACE for ground mount panels. Again, this is expansion room. When you need more power you simply add more panels.
My DC Buss starts at my house, runs through the solar field to the shops where the businesses are. The buildings have panels, but there are panel strings, charge controllers and batteries all along the DC Buss all the way down the hill.
A 300 yard walk or golf cart ride to work, I check status of the panel strings along the way. All 'Green' lights and I'm good for the day (or several days now).
Keep in mind I started with a cake pan sized 'Battery Maintainer' for an automotive starting battery over 30 years ago, so constant expansion as consumption needs increased. I'm still ahead in money considering 30+ years of rate, line fees and tax increases.
Rules...
1. Panels on posts.
Tall posts keep panels away from wildlife, livestock, vehicles, things the mower throws, etc. Doesnt have to be fancy or expensive, I'm still using scrub tree trunks with a hole drilled in them for the mounting pipe...
2. Panels and shade trees are mutually exclusive, you can have one or the other, not both. Watch for falling nuts or limbs.
3. Rotating panels east/west on a pipe, posts set north/south increases production 15%-30% depending on time of year. This also gives you the option to flatten panels horizontally or even turn them face down in storms. Screw jacks (linear actuators, or gear motors are cheap, so are timers to move the panels as the sun arcs across the sky).
15%-30% more production means 15%-30% less panels for the same Wattage.
4. Tall stand off mounts on roofs.
Air gap allows panels to cool better, and that means increased efficiency for very little cost. The air gap also allows heat to dissipate so roofing material lasts longer, saving money on roof replacment intervals.
5. In the woods, you are in the home of birds, rodents, etc. 1/4 inch screen wire on the backs of the panels saves you a TON of chewed wires. If you rotate panels face down during storms, HAIL bounces off the wire... Ever seen panels after a big hail storm? I have, up close and personal.
6. Rotating panels vertically during snow/ice storms eliminates a LOT of work clearing them. All it takes is a stop switch on the pipe mount to do this...
You are on your own for roof mount panels.
7. No exposed wiring.
Panel makers do the bare minimum to pass code, don't be that lazy or learn a LOT of trouble shooting lessons.
Conduit, or slip PEX or other tubing over wiring, heat shrink wires/connectors, use waterproof boxes for junctions. You will thank me in about 6 months when the failures DON'T happen from corrosion, rodents, etc.
Believe me when I say every rodent WILL find exposed terminals.. And cross those trrminals!
I have a collection of flash fried rodents and reptiles in the shop I pulled out of connection boxes, off wiring, etc. It's a wire replacment, fuse, circuit breaker trip/power failure you have to hunt down every time they do...
8. NO 'CHEAP' WIRE!
100% copper every time, every application. You spend a lot of money and time on making the power, wasting it heating wire simply isn't necessary with 'Cheap' alloy wire.
I saw my (then short) DC Buss melt shadow off the ground. That's electrical resistance convertered to heat, power I'm producing but never get to use... And the corrosion nightmares, insulation that dries up and falls off, etc.
Good wire, good solid connections, environmental protection like terminal grease or industral heat shrink tubing. I do the mechanical crimp connection, then fill air gaps and 'Tin' exposed copper with silver bearing electrical solder, then seal up the connection, environmental protection. I had to learn the cheap 'China' alloy wire/cable lesson the hard, expensive way.
If you don't have the time to do it forrectly the first time, where are you going to find the time to chase the failure and repair it several times using cheap terminals/wire over the coming years?
Just some lessons I learned the hard way... If it helps, you are welcome to it.
If it doesn't, it didn't cost you anything.
Disclaimer end.
I started over 30 years ago off grid because I had to, no power supply to my property.
I've been through crappy panels, lead/acid batteries, etc, now operate a Mini-grid that powers homes, farm, businesses with little to no thought about consumption.
Lessons I've learned...
Get away from lead/acid as quick as you can. I had a business that sold lead/acid, talked with factory engineers, saw them produced, learned the difference between consumer and insustral grade, learned the difference between starting, pseudo deep cycle and actual deep cycle.
It's the chemestry, a liquid electrolyte battery is CHEMICAL storage, from the time the acid based electrolyte hits the plates, the clock is ticking on it's expiration date. Period.
Even at 100% State Of Charge (SOC) the battery is eating itself, literally. Below 100% SOC the clock speeds up...
The facts on charge density, usage between Lithium and lead/acid are well known and well published, so do that Google search...
The BIGGEST reason I went Lithium (LiFePO4 in particular) is longevity. They literally last 100X or more longer. This makes them WAY cheaper in the long run for the amount of kWh of work they get done.
Lithium-Ion is lower life span, but more charge dense. Meaning you get more power out of the weight/size. They are NOT the longest life, number of charge cycles.
LiFePO4 is less charge dense, takes up a little more space, but has 10x minimum the number of charge cycle life.
These batteries will sit for years on the shelf, not significantly degrade, and work fine. This is money in the bank for you.
Considering Lithium gives 4 to 10 times the returned energy over the capacity of lead/acid, again, Lithium the clear choice.
Now, this is the part that OFF GRID system owners should think about... Capacity is VERY high, well over the usable energy of lead/acid by 4 to 10 times.
You don't have to have the panels to make the power to recharge lead/acid every day from whatever sunlight you might get.
When you have 4 to 10 days worth of usable power in the same space/weight, you can have no-sun days, still have power, and the batteries can recharge/recover to 100% SOC over DAYS.
These batteries do NOT degrade quickly when at 25% SOC, or 50% SOC, so you can use that in your favor. No blast charging with a crap load of panels & high powered chargers trying desperately to get lead/acid back up to 100% SOC in a few hours...
the closer you get to 100% SOC with lead/acid, the higher the internal resistance gets, that WASTES a lot of the panel power. Losses in the system.
Again, you can charge Lithium with much lower input from the panels simply because the battery accepts the power without converting a large portion into resistance (heat).
In 2010 I got hold of Lithium batteries, several chemestries by coincidence. Started learning and testing, building my own batteries. In 2020 I upgraded a crap load of my up to 30 year old panels and found d between the efficiency of the batteries, using charge controllers specifically designed for the Lithium chemestry, and the Lithium batteries I was getting MUCH more power returned, needed many less panels/total Wattage, and had an embarrassingly large amount of reserve time...
Embarrassingly large because I'd been adding Lithium replacements for lead/acid for 10 years, but doing it on a 1:1 RATED Ah swap. I had about 7 times the useable Ah capacity, and I simply didn't need to have as many panels as I bought since they didn't degrade faster at below 100% SOC.
25 years watching every single Watt had broke my brain, I was stuck in that run believing I needed enough panels to charge lead/acid in 4 to 5.5 peak sun hours... with little or no reserve left in the batteries.
My recommendations are STAY MODULAR! No propritary, all in one systems that lock you into a particular manufacturer. As battery chemestry changes, you can switch to a charge controller that is optimum for the battery chemestry/type/size without changing rhe entire combined unit.
YOU get to pick a reasonable sized inverter that fits your needs. It will often be so inexpensive you can buy a backup, wire the back up in parallel, and flip a switch should one fail and be right back on line, and STILL SPEND LESS.
Off grid, reserve and redundancy matter. Batteries on a DC Buss means you can expand as necessity requires. DC transfer switches are cheap, separate charge controllers are cheap. Inverters can be cheap, so you can often double up and still spend less while getting redundancy.
My panels are on strings, each string has a charge controller. Charge controllers are in parallel. Same amount of Watts/Amps being dumped into the batteries (plural, again, redundancy) and if any one charge controller fails, it's literally flipping a switch to the back-up to get the panel string back on line. I can change the failed charge controller at my leisure, see what the updated unit is for my battery chemestry, and replace with the best unit for my budget and/or the job.
MPPT being built into almost every charge controller, and the technology getting better all the time I don't worry much about updating since these do fail from time to time, so it's an automatic update when something does fail.
It's a CHEAP update, not an $8,000 all in one combined unit replacment.
Expansion.
Almost everyone off grid decides to expand. Again, stay modular. Add panel strings, charge controllers, batteries, inverters as needed. MOST of the larger inverters today will 'Combine', the proper term is 'Gang' together. 2 each $750 ($1,500 total) or even 3 each ganged together beats replacing an $8,000 all in one combined unit.
Off grid youboften have SPACE for ground mount panels. Again, this is expansion room. When you need more power you simply add more panels.
My DC Buss starts at my house, runs through the solar field to the shops where the businesses are. The buildings have panels, but there are panel strings, charge controllers and batteries all along the DC Buss all the way down the hill.
A 300 yard walk or golf cart ride to work, I check status of the panel strings along the way. All 'Green' lights and I'm good for the day (or several days now).
Keep in mind I started with a cake pan sized 'Battery Maintainer' for an automotive starting battery over 30 years ago, so constant expansion as consumption needs increased. I'm still ahead in money considering 30+ years of rate, line fees and tax increases.
Rules...
1. Panels on posts.
Tall posts keep panels away from wildlife, livestock, vehicles, things the mower throws, etc. Doesnt have to be fancy or expensive, I'm still using scrub tree trunks with a hole drilled in them for the mounting pipe...
2. Panels and shade trees are mutually exclusive, you can have one or the other, not both. Watch for falling nuts or limbs.
3. Rotating panels east/west on a pipe, posts set north/south increases production 15%-30% depending on time of year. This also gives you the option to flatten panels horizontally or even turn them face down in storms. Screw jacks (linear actuators, or gear motors are cheap, so are timers to move the panels as the sun arcs across the sky).
15%-30% more production means 15%-30% less panels for the same Wattage.
4. Tall stand off mounts on roofs.
Air gap allows panels to cool better, and that means increased efficiency for very little cost. The air gap also allows heat to dissipate so roofing material lasts longer, saving money on roof replacment intervals.
5. In the woods, you are in the home of birds, rodents, etc. 1/4 inch screen wire on the backs of the panels saves you a TON of chewed wires. If you rotate panels face down during storms, HAIL bounces off the wire... Ever seen panels after a big hail storm? I have, up close and personal.
6. Rotating panels vertically during snow/ice storms eliminates a LOT of work clearing them. All it takes is a stop switch on the pipe mount to do this...
You are on your own for roof mount panels.
7. No exposed wiring.
Panel makers do the bare minimum to pass code, don't be that lazy or learn a LOT of trouble shooting lessons.
Conduit, or slip PEX or other tubing over wiring, heat shrink wires/connectors, use waterproof boxes for junctions. You will thank me in about 6 months when the failures DON'T happen from corrosion, rodents, etc.
Believe me when I say every rodent WILL find exposed terminals.. And cross those trrminals!
I have a collection of flash fried rodents and reptiles in the shop I pulled out of connection boxes, off wiring, etc. It's a wire replacment, fuse, circuit breaker trip/power failure you have to hunt down every time they do...
8. NO 'CHEAP' WIRE!
100% copper every time, every application. You spend a lot of money and time on making the power, wasting it heating wire simply isn't necessary with 'Cheap' alloy wire.
I saw my (then short) DC Buss melt shadow off the ground. That's electrical resistance convertered to heat, power I'm producing but never get to use... And the corrosion nightmares, insulation that dries up and falls off, etc.
Good wire, good solid connections, environmental protection like terminal grease or industral heat shrink tubing. I do the mechanical crimp connection, then fill air gaps and 'Tin' exposed copper with silver bearing electrical solder, then seal up the connection, environmental protection. I had to learn the cheap 'China' alloy wire/cable lesson the hard, expensive way.
If you don't have the time to do it forrectly the first time, where are you going to find the time to chase the failure and repair it several times using cheap terminals/wire over the coming years?
Just some lessons I learned the hard way... If it helps, you are welcome to it.
If it doesn't, it didn't cost you anything.
