DIY 3.6kW bifacial ground mount system

[Subdood]

I recently bought 400 watt bifacials from SanTan also. I mounted them on my patio cover. Before I mounted them, I applied a white roofing coating to get as much as I could from the bifacials. You might think about putting a layer of white rock under your panels. It would also make it so that you wouldn't have to mow under them. Just an idea.

Thanks. I have considered white gravel under the array, but am using the tin sheets and white skirting for now. Yes, it is a pain mowing underneath the mount. How many panels do you have and how long has your system been running?

 

[Subdood]

Update on our system, about to hit half a megawatt/hour PV generated since April. It's passed through about 1.2MWh in bypass mode. Still don't have any batteries, but am planning to pick up a couple 5kwh server rack batts in a couple months. System has been pretty solid, although there's been a few power glitches where the inverter reset itself, but the outages were less than a second. Generation has slipped the last couple months, probably because the days are getting shorter.

 

[Subdood]

Another update. We reached 557kWh of PV generation recently. But that number should increase as my Lifepower4 5.1kWh battery came in yesterday. My wife was home when R+L delivered it. We lugged it up the steps and into the house, the thing weighs right at 100lb, so it was a beast. We left in the living room for now, but will move it onto the solar closet soon.

I unpacked it last night and powered it up and it has about 52V on it and shows about 75% SOC. I also ordered a fuse/holder and 200A DC breaker. Still don't have my wire to hook up to the inverter, need to get it placed into position under the inverter to see what I'm going to need.

As soon as I looked it over, I was thinking of getting another one, but I'll see how this one handles our critical loads. I told my wife once I get everything hooked up, we shouldn't even notice when we lose grid power, since the switchover time is supposedly 20ms.

Here's few pics of it, can't wait to get it hooked up. BTW the package was delivered in pretty good shape, so I'm pleased with that. They had it strapped down onto a small pallet. The truck was able to get up our driveway and off loaded next to our shed.

 

[Subdood]

Last Saturday I received my battery cabling, so I hooked it to the fuse and breaker and then the battery. We lugged it into the solar closet and after I shut off the grid power, I hooked it up to the inverter. After about an hour and double checking everything I turned on the battery breaker, then in line breaker and then the inverter, and voilá we have battery power!

Since then it's dropped down to 30% a few times, and recharged via solar. When the sun is out and the clouds are away, the inverter fans get really loud. At times it's pulling about 50A, or 0.5C, which is a bit high for my liking, but I guess it's okay. The charge current and bulk/float settings aren't changeable with the EG4 batt setting on the inverter.

This morning for example, the batt was down to about 40%, but with being clear and cold, it started charging in a hurry. It started about 8:30, and by 10:30 it was almost fully charged. The array is rated about 3.6KW, so it doesn't take much time at all. Needless to say our PV production has picked up, the last couple days we got over 4KWH the last two days, and might get that much by the end of the day.

I've noticed once the sun goes away about 4pm, the batt drains about 40% in the evening, and once we go to bed, it drains another 25% by daybreak. But, it's not always sunny here in the mornings, so I have to recharge it via the grid often. Because of this I'd like to get one more 5KWh batt, but am waiting on the prices to drop a bit more.

Here's a few pics, it looks a little haphazard, but I plan on attaching the breaker, fuse, and cabling to the wall.

 

[Subdood]

Ok, the battery has been online for a few weeks now. Haven't had any problems with it at all. During these long nights, we can't stay off grid from sunset to sunrise, mostly because we burn through about 50-60% from the time we get home, (usually 5pm) until I go to bed around 11pm. PV generation usually stops by 4pm, and starts about 8am.

Most of that drain is from one or two TV's, frig, several lights, and occasional high power items like toaster oven or microwave, even though they're not on that long. After we go to bed, the max load is about 150W, mostly from the frig running about 20 minutes of an hour. Then there's a couple alarm clocks, modem and a CPAP machine. So from 11pm to 6am, when we get up, the drain is usually 20-35%.

So, from dusk until dawn it would almost completely drain unless I allow the grid to charge it about 10% before I go to bed. I don't want it to get below 20% if I can avoid it, the lowest it's got is maybe 25%. I imagine during the spring and summer, we might be able to get thru the night without any grid charging.

If there's sufficient sunshine it takes about 2.5 hours to charge from 30% to 100%, the last half hour is when the BMS throttles back to about 9-10A when it gets to 95%. Max charge is limited to 50A, which can happen with bright sunshine. This time of year, if there is bright sunshine first thing in the morning it really starts charging about 9am and usually finishes before noon.

Generation per day obviously has increased since the batt needs charging, the sunny day average is about 3KWh/day. Of course not all days are sunny, so we're lucky to get half a KWh then. My wife was home last Friday working from home, and since it was sunny and she did a couple loads of laundry, we got about 5.6KWh, the most this system's produced since it came online in April. The most at any one time was right at the array's rated power, or 3.6KW, that was at max charge of 50A, and a 700W load.

So moral of this long story is..

I need more batteries!

 

[G00SE]

Great thread.
You mentioned the fans ramping up and how quickly the battery charges/50a
You should be able to adjust that parameter in the inverter if desired. I don’t think 50a is anything crazy, especially once you have a second one though
Fan speed makes sense, bringing in more PV to fill the battery so the inverter is working harder. Probably never had a demand of that much instant power to notice fan noise previously

 

[Subdood]

Thanks. I can't adjust the max charge current (50A), or the max AC charge current (20A), I've tried several different ways and it won't take. So, I'm guessing the BMS is setting those for the inverter.

I've read in several articles that 0.5C, or 50A in the case of this 100Ah battery isn't really an issue, so I guess it's fine the way it is. It does back off when it reaches 95%, drops down to 10A (0.1C).

Yeah those fans get quite loud at 35-50A charge, but thankfully it's during the day, so it's not an issue then.

How the inverter talks to the BMS and handles the load and charging while the PV power varies is pretty amazing to me, and I'm an electronic technician.

BTW early this morning, the batt dropped down to 30% before it started charging around 9am, it's pretty much back up to 100% now, so it takes about 2.5-3 hours. I think I have enough PV to charge in one day if I added another 5KWh batt.

 

[Subdood]

Update on the system. We have generated about 730kwh so far, the production over the last couple of months has gone up on average since we added the 5kwh battery.

I had mentioned in a previous post that we weren't able to make it overnight on one charge. Well, now we can, so I'm suspecting all the Christmas lights were a bigger drain than I thought. Now that those are gone, we easily make it thru the night.

Of course we would need sun the next day to recharge the batt, but that's pretty much disappeared the last couple weeks. It's gray again today, but supposed to be a bit sunnier and drier over the next week.

 

[Bleedingblue]

Ok, the battery has been online for a few weeks now. Haven't had any problems with it at all. During these long nights, we can't stay off grid from sunset to sunrise, mostly because we burn through about 50-60% from the time we get home, (usually 5pm) until I go to bed around 11pm. PV generation usually stops by 4pm, and starts about 8am.

Most of that drain is from one or two TV's, frig, several lights, and occasional high power items like toaster oven or microwave, even though they're not on that long. After we go to bed, the max load is about 150W, mostly from the frig running about 20 minutes of an hour. Then there's a couple alarm clocks, modem and a CPAP machine. So from 11pm to 6am, when we get up, the drain is usually 20-35%.

So, from dusk until dawn it would almost completely drain unless I allow the grid to charge it about 10% before I go to bed. I don't want it to get below 20% if I can avoid it, the lowest it's got is maybe 25%. I imagine during the spring and summer, we might be able to get thru the night without any grid charging.

If there's sufficient sunshine it takes about 2.5 hours to charge from 30% to 100%, the last half hour is when the BMS throttles back to about 9-10A when it gets to 95%. Max charge is limited to 50A, which can happen with bright sunshine. This time of year, if there is bright sunshine first thing in the morning it really starts charging about 9am and usually finishes before noon.

Generation per day obviously has increased since the batt needs charging, the sunny day average is about 3KWh/day. Of course not all days are sunny, so we're lucky to get half a KWh then. My wife was home last Friday working from home, and since it was sunny and she did a couple loads of laundry, we got about 5.6KWh, the most this system's produced since it came online in April. The most at any one time was right at the array's rated power, or 3.6KW, that was at max charge of 50A, and a 700W load.

So moral of this long story is..

I need more batteries!

You should buy those grade B envision 305AH from 18650. I have 4 banks of them with a JK bms and have been flawless so far

 

[Subdood]

Well I had to take advantage of SS 's free shipping and splurged on another Lifepower4 battery. Ordered it on 2/29 and it showed up last Thursday (3/7). Got some new cables for it made and hooked everything up last Saturday.

Everything seems to be playing well with each other since then. Now with 10kwh we can get thru a couple days without power, provided there's enough sun to recharge them. Kinda cool to be kinda sorta off-grid. Of course it just runs the 120V stuff, but still nice to have.

I think I'm done with any more solar purchases for now.

Maybe.



Some new pics of the set-up-

 

[Subdood]

Well, it took about a year to get here, but we got here nevertheless.

1 MILLLLLLYUN watt-hours generated, baybee!!

 

[OffGridForGood]

I think I'm done with any more solar purchases for now.

Maybe.

Naw,
more power! MORE!!

 

[Andrewr05]

Awesome build.
The step by step blog type updates are always a great read though.

 

[Subdood]

Naw,
more power! MORE!!

In the words of Al Gore, "I'm totally serial.."

I'm good for now, got to let the kitty fill up a bit more before the next step.

My next project is completing the renovation of our old chicken coop that I promised my wife.

 

[Subdood]

My system hit 139KWh yesterday, our best month ever, so we should be above 140K easily with a couple days left.

There was a about 35ft sycamore tree that cast a long shadow across my array late in the afternoon which impacted late day production. It leans out about 45 degrees compared to the other trees. So yesterday I got out the chainsaw for the first time this year, sharpened the chain, gassed and oiled it up. Thought I would fell me a tree.

The trunk was about 14 inches thick at the base and my 16in Stihl took it down pretty easily. Until I tried to cut it completely off the trunk and the tree rolled a bit and snagged the top of my saw and wouldn't let go. It took a lot of maneuvering and cussing to get it loose.

The chain wouldn't turn on the bar because there were wood bits embedded in the spindle on the end. So I had to pick out the woody bits with a screwdriver and oiled it up and eventually it started turning again.

After wasting ten minutes getting the chain back on, I cranked it back up and it wouldn't cut anything. Idiot put the chain on backwards. Arghhh. Finally got it on there right and started chopping up the tree and hauled branches down to the burn pile.

We'll see if that makes a difference. There's about half a dozen more trees I'd like to cut down but this will do for now. But don't want to cut too many down as they give our house shade in the afternoon.

I like my saw, it has an automatic choke on it so I don't have to do much to get it started. Most saws wear your arm out trying crank, but not this one. Adjusting the chain looseness is a pain because it tightens up after it warms up from use. But after using it a few years I seem to have figured that out. Sharpening the saw is a chore, but it's not too difficult. It's a Stihl MS 180CBE, got it about 5 years ago.

What kind of chainsaw do y'all have?

 

[Subdood]

Well we got right at 150KWh generated for April, another best ever month. Plus we only used 422KWh overall, so our electric bill was only $62, which is the lowest we've ever seen that I can recall, and we've been here ten years.

Helps when we no longer need the heat, and the AC is used sparingly so far. Most of that 150K goes into the 10KWh battery bank, but it's nice to see it's making a difference on our bills.

 

[Drunkin Solar]

What kind of chainsaw do y'all have?

Been cutting a lot of wood clearing land.

Bought a little used Echo CS400 15 years ago. I have literally beaten the snot out of that saw and it just keeps on ticking. Just a tune and clean now and then replace the primer bulb every two years and installed a carb kit about five years ago. Plus replace the normal worn bars, chains and sprocket.

I have since grown to four Echo saws spanning from a little 12" climbers saw up to a 36" hog. I recommend them all.

Your solar build is excellent. Glad to hear you are reaping the fruits of all the hard work and expense you've put in.

 

[Subdood]

Don't think I've heard of Echo saws, but I'm somewhat of a noob when it comes to them. Wow, a 36" saw? That's huge. You must be cutting some big timber.

All I know is that they can be a bear to start sometimes, and I wanted something easy to start. With this MS180, I just set the choke on it, and give it a few small tugs and it starts right up. I've had it about 8 years and it's been pretty reliable for me. But I only use it a few times a year. Guess you would call it a light duty saw.

I don't like to sharpen them, but have slowly learned how to do it myself after my bro in law taught me. The biggest pain for me is getting the chain tension right as it changes as it warms up. But, there's just a couple of small dial adjustments that need to be made.

Thanks about my ground mount, looks like it's paying off a little every month, plus we got a decent tax credit on it, so it's not too bad. One thing I will say is there's a lot of extra costs that go into building a system, especially a ground mount. There's all the lumber, conduit, wire, hardware and so on that you will need to anticipate. It's "easy" to buy all the equipment, but it was a chore to install it and the infrastructure for it. But it was also rewarding to do it myself.

 

[Drunkin Solar]

None of it is "easy" if your not experienced
I also have a substantial investment in ground mount hardware for a smaller array of 3.2kw. It's not installed yet but I built another identical one for my son a few years ago. It all really adds up quick on initial outlay but the payback seems to come pretty quickly.

If you don't run your chain saws day in and day out the Echo's are a great professional saw I just don't know if they will hold up as long as a Stihl.
They cost about half as much but start easy and run great. Yes my 36" is a beast and hogging wood with it you better hang on tight. Have cut 6' diameter logs with it, figure the tree was at least 250 years old. Made great firewood out of it!

Bought a chain grinder some years back to sharpen the chains. It has sharpened enough chains at this point it has paid for itself several times over.

 

[Subdood]

None of it is "easy" if your not experienced
I also have a substantial investment in ground mount hardware for a smaller array of 3.2kw. It's not installed yet but I built another identical one for my son a few years ago. It all really adds up quick on initial outlay but the payback seems to come pretty quickly.

If you don't run your chain saws day in and day out the Echo's are a great professional saw I just don't know if they will hold up as long as a Stihl.
They cost about half as much but start easy and run great. Yes my 36" is a beast and hogging wood with it you better hang on tight. Have cut 6' diameter logs with it, figure the tree was at least 250 years old. Made great firewood out of it!

Bought a chain grinder some years back to sharpen the chains. It has sharpened enough chains at this point it has paid for itself several times over.

At first getting into solar was a bit intimidating but I've slowly learned enough to feel comfortable building a complete system. My original goal was to have a 6KW inverter, 8KW array and 10KWh battery bank, so all I need now is another 4KW of panels, which seem to be getting cheaper by the day. Might add that array later in the year, but don't know how I'll set it up. Don't even know it'll be another wood one. This one is a year old and seems to be holding up well, though.

So what kind of setup are you looking at? Like what type of ground mount, inverter, batts, etc? Whole house or critical loads? Ours just runs 120V stuff, but I hope to move up to some bigger loads, but that would require more panels and a split phase inverter.

A 6ft diameter log, what kind of tree was that? We have 50 acres in the Appalachian foothills, most of it forested. We were hoping to get some white oak harvested but a local logger said our trees are still too small or not accessible. I think it had been logged maybe 30 years ago so I'm thinking the best timber was harvested then. Most of our big trees are tulip poplar, sycamore, red oak, some pine. If we ever get a wood stove my wife wants, we sure have enough timber to feed it..