David Baillie

R Scott wrote:Because the “algorithm” rewards yellow journalism.

Yup, It's high school math. His reasoning for why we use larger cables is also dead wrong. We don't use thicker cables to carry the amps in this case we do it to reduce voltage loss to a low enough percentage to pass an inspection. Here it is under 2 percent some places in the States its 3 percent I'm told. If he had used the 12 gauge he was commenting about he would have been way over that over 400 ft.
I'm sure if it gets enough views someone else will remake the same damn video and "discover" it all over again. It's not a bad video. I don't see a disconnect at the array so that would be an automatic fail here, He is using an anker Solix which is a portable unit which I would not recommend for permanent install. Those all change with jurisdiction of course. I am also finicky about this stuff...

Douglas Alpenstock wrote:Wow, I'm shocked to discover I'm waaaay behind when it comes to the current state of solar. Thanks for the updates guys!

Douglas, for the longest time you could just spec out a magnum inverter a midnite solar charge controller and 3-5kW of solar and go home. Then China decided to push solar hard. Its impossible to overstate how completely they now own the industry. Cheap lithium options, panels and incredibly powerful inverters have turned everything upside down and halved prices... Solar arrays are now huge, lithium batteries last for 20 years the sky is the limit. Unfortunately there is also a proliferation of low end junk as well. Its now the wild west. I'm fairly conservative in my design choices sticking to companies with a North American presence for support.
Cheers,  David

John Weiland wrote:

David Baillie wrote:.............The transformation happens at the inverter mounted near the end user. You should plan on a good steel jacketed teck cable and metal junction boxes or trays all the way to the inverter to minimize risk. Use a high voltage rated isolation switch at the array and high voltage rated Breakers at the inverter. It costs money but saves money in wiring and allows for much larger systems. It boils down to size of system, how far out you are and the level of loss you are willing to take.

David B.,   Does this suggest that micro-inverters installed within each panel are going by the wayside now for the industry at large?  If I'm thinking about this right, micro-inverters would kick the DC voltage from the PV panels into 120VAC (yes?), which would reduce line loss (correct?) and possibly allow for less expensive cabling from panel to destination, although best not to skimp on that with any wiring exposed to the elements.  For battery charging, this would need to be converted back to DC at the destination point.  But I thought one advantage of micro-inverters was being able to grid-interie without an inverter positioned near the end-user.  Thanks....

I would agree with phil,
The only situation where micro inverters still have a role is on roof mounted arrays or ground arrays close to the house that face shading issues. Micro inverters convert from say 40 volts dc to 240 volts AC but nobody would run a single panel voltage string unless it was a one panel trailer system so there is no advantage there. A 500 volt dc string will have half the power loss of a 240 volt ac feed from the micro inverters. Even on roof mounts a more common solution is becoming panel installed rapid shutdown receivers and a ground mounted transmitter and again a 500 volt dc feed... Design is getting to be more and more site specific as the solutions multiply. For the original scenario of 200 ft from the house a high voltage all in one inverter like the solark or the lux would be the usual solution if you are pairing with batteries,  If you are just feeding the grid a fronius or a sollis or a solar edge would be my choices.

Bob Nall wrote:I'm curious if anyone has solar panels in a field approx 200+ feet away from their home.  What is the preferred method for transferring power to the home inverter and batteries?  Has anyone experimented with voltage drop at those distances?  I was recently watching a youtube video on a water generator and he said something interesting, "if transferring power at the same voltage, DC is actually more efficient than AC." This goes against what many of us believe but it seems there is some truth to it.  So it seems the higher the DC voltage I can transmit it at the more efficient it will be and I will also not have the restriction of eddy currents as I would in AC.  Has anyone ran high voltage solar DC wiring at length?  I am able to input 2 165V DV inputs into my unit, but I also understand at this point the DC voltage is getting to a "not safe" point.  Obviously roof mount is an option but requires a lot more code and inspection processes.

As a general rule modern systems are going to a higher and higher voltage coming in from the solar strings. Most all in one inverters are accepting a 300-500 VDC input charging a 48 volt battery. We regularly go out 200-300 ft from the inverter and stay bellow the 2percent loss we have to adhere to in Ontario. This is a big change from the older 150-200 volt charge controller based systems we used to use. The transformation happens at the inverter mounted near the end user. You should plan on a good steel jacketed teck cable and metal junction boxes or trays all the way to the inverter to minimize risk. Use a high voltage rated isolation switch at the array and high voltage rated Breakers at the inverter. It costs money but saves money in wiring and allows for much larger systems. It boils down to size of system, how far out you are and the level of loss you are willing to take.

Rachel Michelle wrote:

tony uljee wrote:clear plastic sheeting --as from polytunnel material--its uv treated --transmits 80 percent or more of light--and use the clear repair tape to hold it down around the framework----would be the cheapest ---next would be the specialist sticky back stuff applied to windows turns them into safety glass

I like the simplicity of that! But would condensation be an issue?

Eventually humidity will get in and start corroding the solder but if sealed well it could take years. Any of the methods listed should work. I used to have a shattered one in my hoophouse to keep it dry; Worked for years.

Allen Jackson wrote:Out of curiosity David, what if they aren't "lithium" batteries?

if they are not lithium its a vented to the outside box with a powered fan. Must be in a dedicated mechanical room, must have a smoke detector, must have a headroom of 6'9". Most of those apply to lithium as well except the venting and box.

Allen Jackson wrote:

David Baillie wrote:Hi Jackie,
I do not see on the link anything about UL9540 compatibility or certification in Europe or North America.

I haven't seen anything about UL9540 compatibility either, so I started digging...

For the most part, it doesn't matter, and it's NOT applicable!

Let me explain. UL 9540 is the standard, to which energy storage systems are tested.

UL 9540A is the testing method of those systems to determine & evaluate their capacity for thermal runaway in a fire.
(This is used to determine how close they can be to each other, and most of the requirements don't apply to single and 2-family residences)

UL 9540B was developed to specifically address residential energy storage systems.

While UL 9540 is NOT just for lithium ion batteries, it really doesn't have much to say about LiFePO4 batteries. Because it's primarily focused on fire hazards and fire safety, it covers lead acid batteries, which can generate explosive hydrogen gas, and lithium ion batteries, which can be driven into thermal runaway by damage or heat. Since lithium iron phosphate batteries don't exhibit those characteristics, they already inherently pass the basic cell-level test requirements of UL 9540A (or UL 9540B), and per the testing norms, if the cells cannot be driven into thermal runaway, there's no further need to test the module or system that they are installed in.

UL 9540B was driven primarily by California fire code, that became more strict than UL 9540, to focus on the gaps in coverage of residential systems (pretty much due to the rise in popularity of Tesla Powerwalls and Tesla vehicles), because they DO use lithium ion batteries, and are most commonly found in residential settings.

Unless you're planning to install a DIY lithium ion based system the applicable regulatory agencies aren't likely to be paying much attention to your systems, unless there's an outside chance you're looking at a large scale installation of lead acid batteries, because of the hydrogen generation).

The fervor over insurance companies and inspectors not liking LiFePO4 battery systems, is only possible if they are ignorant of the differences between lithium ion and lithium iron phosphate batteries. It's even likely that inspectors will see the word "lithium" and automatically assume that a system is equivalent to a Tesla powerwall. That doesn't mean it can be set on fire, though...

All valid points and I agree with all of them. My point was that where you are matters. Where I am (ontario) I must have all battery systems visibly labelled by the manufacturer as 9540 compliant. On top of that I must have manufacturer applied labeling stating that the lithium battery in question has been tested with the inverter in question for closed loop communication Or I simply will not get it passed by the ESA. Without an ESA passed system mortgage companies will not cover the home and insurance companies may or may not cover any claim.  Its a bureaucratic nightmare honestly and I often want to throw my hands up. The response from the manufacturers is to come out with inverter specific batteries such as the Lux, the EG4, the sigens, soon the outback...  Personally I've taken to specking a dedicated power shed for new larger systems. My current approved match up are the lux or solark inverters with the pytes batteries. I've had several systems pass that way.
Cheers,  David

Allen Jackson wrote:There has been a bit of talk in this thread about essentially the fear of what happens if the BMS in a lithium battery dies, and if those batteries are a commercial pre-built system, I suppose those concerns are real factors in the decision process. If you build a battery from parts, it's really not an issue, because you can still use the cheapest parts around, but if/when they fail, you can still replace them, you can upgrade them to less cheap parts, or you can replace them with the best quality parts available, now that you have experienced the functionality the battery system has brought to your life.

I'm not a big fan of buying commercial battery systems any more than I'm not a fan of buying a pre-built computer for a specialized use. "If you want a 'gaming' computer, build it to meet the junction of your needs and your budget, don't buy into the marketing of what some sale/marketing team decided would be flashy enough to bump their profit margins...

LiFePO4 batteries have become a commodity item, that's too easy to duplicate with readily available components, that it's hard to justify the extra expense of buying the package, unless you really wanted/needed the convenience of buying it and plugging it in, then quickly moving on to something else. For the same reasons I'd avoid the pre-built 'gaming' computers, manufacturers of battery systems are still for-profit businesses, that will cut corners to appeal to the middle of the bell curve, since that's where the profit is. If you happened to want or need anything just outside of that, you end up compromising your needs, or wasting time/money to do it over just to get it right. DIY doesn't mean that you don't have to do anything over, it just increases the speed with which you can, plus it drops the cost of doing so.

Case in point, last week, I built a LiFePO4 battery that I was & am very happy with, but I wasn't happy with the BMS or the "brains" of the battery. Yesterday, I replaced the old BMS with a much better matched one for my needs and it pretty much just involved using a screwdriver to swap the connections.

Allen, I respect your desire to build the battery you want for a specific application. My issue is when people install non certified gear in their house and expose themselves to all sorts of insurance and mortgage complications because of it. Some areas are more forgiving but a non certified piece of gear become a great way to deny a claim whether it was at fault or not. The good thing is the technology is so much better than even 3 years ago and good safe solutions are common and dropping in price.
Cheers, David

I do like a dc only solution. You are 100 percent correct that for irrigation using a tank as a battery is a great low cost solution. I to wonder about that switch but it looks like a good old fashioned  type with heavy duty contactors. Some of them were built for ac or dc so it might work out.  Keep an eye on it for carbon build up and arcking
Cheers!
David