Grid-tied solar

[Carl_NH]

Too much information ?

I tend to do that.......

No - you explain things well and clear - much appreciated since when you see kits on line for x KW they don't really go into the electrical aspects and wire size and details needed.

Thanks again,

Carl

 

[TnAndy]

Enphase is kinda nice in that you can see how many systems are around the world (for those that have chosen to allow a limited, public view of their data....most do...it actually defaults to that unless you opt out), and get details on specific ones (the public side)....190,000 systems around the world. You can zero in on your area and see if any of your neighbors have an Enphase system.

https://enlighten.enphaseenergy.com/public_systems


For that one above I finished up last month, today is his one month online day.....his system has produced 1239kwhrs for the month it has been in operation. You can mouse over the blue boxes and see the daily production. Today, for example, was fairly lousy because we had only a little sun this morning, and rain most of the afternoon. He only did 12.3kwhrs today. On a good day, he will do mid-60's.

Click on "Energy Production"....it has Months, Days, Hours. If you use the hours section, you can about tell the sunshine quality of any give day.

https://enlighten.enphaseenergy.com/pv/public_systems/sntr451420/grid/months

 

[Redneck in training]

Enphase is great for DYI installation. Certain disadvantage is that it can't be islanded or used to charge batteries while off grid. If you can install a breaker and/or new outlet you should be able to install PV system with microinverters.

 

[farmer2009]

Good info. Nice web site to track generation.

 

[TnAndy]

Enphase is great for DYI installation. Certain disadvantage is that it can't be islanded or used to charge batteries while off grid. If you can install a breaker and/or new outlet you should be able to install PV system with microinverters.

Yep....that is true. They are designed for grid tie ONLY situations. No grid power, they shut off. Folks considering a system need to get that important point.

But on the plus side, the install is so much more simple, and far cheaper.....batteries ain't cheap. One needs to decide WHY you want a system.....backup power, OR strictly reduction of electric bill......then pick which road to travel. My guess is 90%+ of grid tied systems do not include backup power. And that's OK, as long as you understand the difference.

My own system, I started with a grid tied, battery backup system using a pair of Outback 2500w inverters. (master/slave arrangement gives true 240AC output) I have 6kw of panels on that system, which maxes out the 5,000w output of the inverters. If grid power goes down, I flip a transfer switch, and we keep on operating off that amount of power. It's enough to take care of the basics...refrigeration, lights, and a few other uses I consider important.

Then I added 5kw of Enphase based panels/inverters that grid tie only.

Between the two, we have no electric bill, and generate about a 50-60 buck/mo credit. They will issue us a check at the end of the year if the amount is positive. Right now, we're up about 500 bucks.

Redneck IT:

Visited your Enphase site....WOW....that's a heck of a system ! 96 inverters = about what, 24kw system ? That's a honking BIG system.

 

[ultrarunner]

Anyone have this inverter which is grid tied AND provides a single outlet without batteries?

Seems like a practical solutions... enough to keep data or maybe a refrigerator working?

SMA 5000TL-US Sunny Boy Grid Tie Inverter with Emergency Power Outlet

 

[buickanddeere]

Anyone have this inverter which is grid tied AND provides a single outlet without batteries?

Seems like a practical solutions... enough to keep data or maybe a refrigerator working?

SMA 5000TL-US Sunny Boy Grid Tie Inverter with Emergency Power Outlet

How does that operate a few priority loads when the utility grid goes down and there are no batteries ?

 

[Scooby074]

How does that operate a few priority loads when the utility grid goes down and there are no batteries ?

It will only generate AC from whatever DC is present. Ie: if the outage is at night you are SOL. I dont believe there is a way to add a battery pack to the unit to provide some overnight power. I suppose you could use the "emergency" power to charge up a UPS or something similar.

"he Sunny Boy 5000TL-US ships with a handful of new features including an SMA exclusive Secure Power Supply (SPS) which can provide up to 1,500 watts of dedicated power in the event of a daytime power outage"

 

[buickanddeere]

A battery buffer is required. You can't operate a typical AC load with just solar panels and an inverter with nothing in between. If the inverter is grid tie it's not going to output power with the utility down.

 

[TnAndy]

A battery buffer is required. You can't operate a typical AC load with just solar panels and an inverter with nothing in between. If the inverter is grid tie it's not going to output power with the utility down.

Near as I can read, there is no battery in the unit. (no actual experience with these)

My guess is they use some capacitors as a very small buffer, but when the power from the panels falls to a certain point, it simply shuts down the limited off grid outlet.

Or it may simply be a case of full 1500watts ( if you have enough sun on the panels), or nothing (if it falls to 1499w)...I wouldn't think so, since that would play havoc with some electrical things....one one second, off the next if a cloud passed over, on again shortly later. ( Which IS one reason you typically want batteries in an off grid system....a GOOD buffer)

 

[ultrarunner]

I spoke with someone from the company and I do not believe there is any battery(s) involved.

It produces limited real time power from available sunlight and that is it.

The person I spoke with said the intent was to provide an option... such as a small refrigerator, electronics or even charge battery packs.

I'm intrigued because this is the only combination I have found off the shelf that promises grid tied power AND the possibility of limit daylight power with the grid down.

I'm hoping this is just the first step in that direction... otherwise, I like the enphase micro inverters...

I've talked to a number of solar people this year... everyone from the kiosks at Home Depot to licensed Solar electricians/installers... only one even knew of the Sunnyboy option...

Just goes to show you need to do your own research!

 

[Scooby074]

I spoke with someone from the company and I do not believe there is any battery(s) involved.

It produces limited real time power from available sunlight and that is it.

The person I spoke with said the intent was to provide an option... such as a small refrigerator, electronics or even charge battery packs.

I'm intrigued because this is the only combination I have found off the shelf that promises grid tied power AND the possibility of limit daylight power with the grid down.

I'm hoping this is just the first step in that direction... otherwise, I like the enphase micro inverters...

I've talked to a number of solar people this year... everyone from the kiosks at Home Depot to licensed Solar electricians/installers... only one even knew of the Sunnyboy option...

Just goes to show you need to do your own research!

My understanding as well. Limited power output is provided to a maximum of 1500W, only when the sun is shining. If there is more than 1500W draw or the sun goes out, the system goes offline until the load is reduced or their is enough sun. Its mentioned in the video I posted earlier.

From what Ive read the Sunnyboy units (not just the ones with the AC outlet) are top quality ones. IIRC Sunnyboy (SMA Solar) is out of Germany. Dave Jones (EEVBlog) installed one and was quite impressed.

 

[TnAndy]

I'm intrigued because this is the only combination I have found off the shelf that promises grid tied power AND the possibility of limit daylight power with the grid down.

If by "only combination" you mean a non-battery based deal, then yep....I think they are the only one.

Personally, I think it's more of a sales tool than a real power source. Very limited power....I sorta doubt you could count on it to keep a refrigerator running unless the power outage was just a couple of hours between the hours of 9am and 3pm (ish). Put a 5kw system in, and look at the power generation before 9am, and after 3pm (generally), and you'll find there isn't enough to generate 1500wAC output.

But there are other grid tied systems that have battery backup for offline. The Outback GT (Grid Tie) series inverters give you full inverter power off line when the grid is down. They do this with a set of contacts that close when the grid tie contacts open (grid down). That extra set directs the power to where you want it.

Typically, that would be a transfer switch (like you'd have on a whole house generator) and a subpanel of circuits connected to the transfer switch. I have 5,000w of Outback inverters set up this way, along with 1200amp/hr@24vDC battery bank. We can operate refrigeration, lights and a few limited electrical 'goodies' almost indefinitely as long as we get decent sun every couple days.

 

[aczlan]

If by "only combination" you mean a non-battery based deal, then yep....I think they are the only one.

Personally, I think it's more of a sales tool than a real power source. Very limited power....I sorta doubt you could count on it to keep a refrigerator running unless the power outage was just a couple of hours between the hours of 9am and 3pm (ish). Put a 5kw system in, and look at the power generation before 9am, and after 3pm (generally), and you'll find there isn't enough to generate 1500wAC output.

I wonder how well such a system would work in tandem with a small inverter generator (with the inverter generator providing the "base load" to make the inverters think the power is on) to allow you to run more stuff in the daytime?


Aaron Z

 

[ultrarunner]

What kind of battery bank are you using?

My neighbor did a total install going on 5 years now... he did it as a present to himself for his 75th birthday... it is grid tied and has a sunny boy invertor.

Had a heck of a time getting utility approval... seems he was one of the first owner installs... he pulled the permits, had the inspections and did all the work himself... retired phone company engineer that came up through the ranks.

His morning ritual is to see how much power he generated the day before...

 

[TnAndy]

I started with a set of L-16 Deka batteries. 6v, 400amp/hr, 8 of them in two strings of 4ea (800amp/hr@24v). About a year later, a guy I know off the internet calls me up and said his cell phone company was being bought out, and he was told "sell everything in the warehouse for scrap". He had a couple sets of brand new Absolyte brand AGM (absorbed glass mat) batteries. He was out in western Kansas. I asked him "how much was scrap price? " (cause they are about $15,000 new !) He said "$300".

I replied "I'm walking out the door and driving to Kansas as we speak......DON'T SELL THEM !"

So, two days later, I pulled back into my place with 3 sets....he had two brand new, and one that had been in service for 4 years, but tested fine. Cell companies just replace them on short time intervals. These batteries are designed with a 20 year life if kept mainly in float mode and not cycled too often....which cell companies don't.....they are simply there so people don't miss those vital text messages to bring home milk and bread....ahahahaaaa

I kept one new set, sold another to a guy from Michigan that drove down and got them, and gave the used set to a buddy with a small off grid system that co-drove out there with me. The set I sold paid for mine, my buddies, and our trip out/back.....so we basically got a free set, except for a couple days of driving time. (like 3,000 miles RT)

These are 2v cells, (250lbs each) with 2 positive and 2 negative terminals per cell. The cells are packed 3 to a 'case'...each metal case bolts either to I beam base, or to each other, so you can stack as many as you want....4 in the case of a 24v pack. Whole pack weighs in the 3000lb range. Those buss bars are solid copper with a tin coating. Even comes with a nice lifting strap that bolts to the cases. Google ABSOLYTE GNB PII.....you'll be amazed.

 

[ultrarunner]

Sounds like you are well connected...

I appreciate the knowledge base TBN offers... lots of interesting projects and solutions...

 

[TnAndy]

I wonder how well such a system would work in tandem with a small inverter generator (with the inverter generator providing the "base load" to make the inverters think the power is on) to allow you to run more stuff in the daytime?
Aaron Z

My guess ( and it's purely a guess ) is grid tied inverters could be 'fooled' by something like you suggest.

Again, you would need a battery bank as a buffer, because if you loaded up on use, and a cloud goes over, you're gonna have a brown out, and maybe kill some equipment....then you get into charge controllers to maintain batteries, and such....so it's not a simple connect A to B kinda thing. If you want off grid capacity, you ought to get it the right way from the start, not try backing into it later....IMHO.....

My own system is a combination of 5kw of grid tie only inverters (Enphase micro inverters), and 6kw of Outback, battery based inverters. My thinking is SHOULD the grid go down for a long time, I could simply connect the output of the Enphase inverters to the off grid output side of my Outback inverters (which puts out cleaner power than the power company), and the Enphase inverters would probably recognize that as "grid" power...and fire up. I haven't done it, and I don't know if it will work, but in theory, it ought to. I wouldn't bother unless the grid looked like it was gonna be down for a LONG time, and I had 5kw of solar panels/inverters sitting there doing nothing anyway.....yeah, I'd be tempted to give it a shot.

 

[ultrarunner]

I was just starting a post as the Blue Angels did a fly by...

Fleet Week in San Francisco, temps in the mid 80's, blue sky and calm...

Still remember one year in practice when one of the pilots flew up Market St below the height of the roof tops... people were actually looking down as the buildings shook...

Totally off topic...

Been watching them take off and land at Oakland airport... must be a thrill for the Southwest Pilots in the landing pattern.

One of the reasons I'm leaning to enphase micro inverters is because they are scalable... in that you can add to the system without having to size a large inverter.

 

[TnAndy]

Sounds like you are well connected...

Yep....I've got dozens of friends I've never met.....ahahhaaaaaa

But I try to return favors whenever I can.

I appreciate the knowledge base TBN offers... lots of interesting projects and solutions...

Ain't THAT the truth ! I participate in several equally interesting forums and am always learning stuff. Since I retired, it's all projects all the time around here ! Talk about living the dream......

My latest project is solar water heating....first leap into this area. I just got the equipment in Friday for a 48 tube (evacuated glass tube type) collector, 120 gallon tank. I'm going to try some in-floor heating in a small hoop house wife and I built last fall......see if we can keep it above freezing in it this winter. Poured the floor with runs of PEX in the concrete and in the raised beds, now we'll see how solar does for keeping it a bit warmer. Last year we spent a lot of effort putting frost blankets over plants, and only grew cool weather stuff. Like to up our game this winter.