Solar panels for you house/ shop

[pembol]

Thanks for everyones response. Here are answers to some of the comments.
I am in Western Colorado and have 300 days of sun. We get very little hail.
We only have one power company to choose from.
I use very little electricty in the summer, and alot in December-March.
My bill in the summer could be under $100 and in January could be $350
What is changing is I just built a new shop that looks to double my usage.
Also the power company has rate increases every year around 7%
I expect this to increase in the coming years due to switching to renewable energy.
I met with the solar company yesterday to get some info. I wont buy until I do more research.
The only rebate is a 30% tax credit through the federal government.
I would probably mount it on the ground instead of on my roof.
My state does NET metering at 1:1 for a usage credit or if they paid me it would be 3:1
I would be fine if I could overproduce for 8-9 months and then use the credit that was built up to offset my usage the other 3-4 months. I would have to pay the power company $7 per month to be connected but I would have a stable and consistant monthly bill.
Brian

We are also in Colorado and just installed a 10kW grid tie system on our house, which for now completely powers our house, shop and EV. Our total energy bill (no natural gas, propane and almost no petrol) is a fixed $7 per month.

Colorado is about as good as it gets for solar, lots of sun and a supportive PUC/government. Net meeting is a requirement, and there is no requirement to 'balance' your account every year - so you can carry credit forward indefinitely and never have an electric bill. In our first year (with no EV) we ended up about 5 MWh in the black, so we now have that buffer to carry forward for the 2-3 months in the winter when we use more than we produce.

We went with a commercial install as this was on a new build and the solar had to be coordinated with the builder. If you are electrically handy, I would consider a DIY install, as long as it meets your utility requirements. Someday I want to heat/cool my shop and will likely add a small DIY system to the shop roof to offset that - mostly for the fun/education part of it.

 

[Just_Steve]

Sub panel and control box.

Must be a reason why the companies I had estimates from didn't do sun light backup systems if it's as easy as you say. Cost wasn't an issue because I wanted what I wanted.

 

[dcg9381]

Must be a reason why the companies I had estimates from didn't do sun light backup systems if it's as easy as you say. Cost wasn't an issue because I wanted what I wanted.

Pretty normal for most PV solar companies to be working with a battery / backup system provider these days.

Cost not being an issue has a scale... I'd expect a starting point of about $30k-$40k for one of these systems capable of providing partial power to home. It's cheaper to do a generator for backup and a PV solar system for grid tie (they won't work together), but you have to design for it.

 

[reader2580]

From Wikipedia

Enphase Energy, Inc. is an American energy technology company headquartered in Fremont, California, that develops and manufactures solar micro-inverters, battery energy storage, and EV charging stations primarily for residential customers. Enphase was established in 2006 and is the first company to successfully commercialize the solar micro-inverter, which converts the direct current (DC) power generated by a solar panel into grid-compatible alternating current (AC) for use or export. The company has shipped more than 48 million microinverters to 2.5 million solar systems in more than 140 countries.​

Enphase is not a crappy Chinese inverter that plugs into a 120 volt receptacle. I have Enphase microinverters in my solar system, but they are properly wired and permitted. They are certainly not plugged into a 120 volt receptacle.

 

[reader2580]

Solar has a bad rap because these install companies want to retire off of just 2-3 jobs. It is almost all profit for them. Mine cost $4k total out of pocket, and took me 2 days to install. The studying up front is where most of my work was, but happy to spread that knowledge now. 2.5 year ROI. Even if you are not up to doing the work, you can still buy the components yourself, and then just hire each part out for a per hour labor charge. Roofer to install the racks and panels, and then electrician to wire it up. Will keep the cost WAY down vs a door knocker. The ROI is too far out if you just pay a solar company.

You must have gotten the deal of the century to get all of that for $4,000. Just the Enphase microinverters in today's market would cost close to $4,000. I did my system DIY and the total cost for 35 panels on ground mounts was just about $22,000 before the tax credit. Now, my system included new meter base, emergency exterior disconnect switch for house service per 2020 NEC, and 175 foot trench with appropriate wire for that distance.

 

[davejo]

Sub panel and control box.

My impression is that certain components are required before enphase allows you to commission the units and only after the installer is certified by enphase. ie control box unless you are talking about 3 generations older stuff

 

[theoldwizard1]

For SMALL micro-inverter installation, the output of the inverter PLUGS INTO A STANDARD 5-15 receptacle. Simply unplugging it is your disconnect.

Now, those statement do NOT mean a system like that would be APPROVED by the local authorities and your POCO !

Why do I get criticized for making statements when they are qualified like the one above ?

 

[dave*99]

Why do I get criticized for making statements when they are qualified like the one above ?

You made a statement about plug in solar, folks had questions. You posted a quote about Enphase. Seemed logical that you were associating the 2 together. Others felt Enphase did not make such equipment. There was no clarity or direction to your string of responses. Some took that as argumentative. Some folks regard ALL CAPS AS SHOUTING. Go back and read your posts. If so motivated, write a coherent and complete summary statement. Preferably one that the OP would find relevant to his original question (although that is not always the case on GJ). Read it carefully before hitting send.

 

[Just_Steve]

Any plug in system would be illegal and dangerous unless totally off grid.

 

[ToolsRCool]

You must have gotten the deal of the century to get all of that for $4,000. Just the Enphase microinverters in today's market would cost close to $4,000. I did my system DIY and the total cost for 35 panels on ground mounts was just about $22,000 before the tax credit. Now, my system included new meter base, emergency exterior disconnect switch for house service per 2020 NEC, and 175 foot trench with appropriate wire for that distance.

It was 7 years ago. You're right though, I don't know current prices of any of the components. Your system is more than 50% larger than mine, I used 21 panels.

My wiring was minimal, as I had a 60 amp 240v feed to my detached garage already, so all I had to do was plug the two 240V hot leads from the inverters into an open double pole breaker in my garage sub-panel. Also broke that feed line at the house to put in a small and simple (solar) disconnect next to the meter (it really cuts the entire garage feed, but fully legit).

The Enphase stuff was not as costly as it likely is now, I have their inverters only (IQ6+ if I remember correctly?) plus their wi-fi monitor box (not required, just if you want to connect to the inverters to witness performance, faults, etc.....), no ATS.

The Federal tax credit at the time was 36%, it tapered down a couple percent points each year after, etc...... I really only had to buy panels, inverters, and racks. Inverters and racks I simply asked for a discount when placing the order from the solar warehouse distributor, and the lady gave a pretty generous one.

 

[reader2580]

It was 7 years ago. You're right though, I don't know current prices of any of the components. Your system is more than 50% larger than mine, I used 21 panels.

My system is bigger, but I still spent more than fives times what you spent. I also did work to my house electrical system to make the solar work. I am well over what be fed into a 200 amp panel by code. I had to replace the meter base to do a tap at the meter.

 

[walrus]

Not required !

GOOD quality micro-inverter can be DIRECTLY attached to your main panel after the first disconnect. You can have 2 micro-inverters as long as each is attached to a different leg.

Enphase micros put out 208 or 240.

 

[theoldwizard1]

Enphase micros put out 208 or 240.

So you need a 6-15R or a 6-20R receptacle and appropriate wiring and breaker.

 

[reader2580]

So you need a 6-15R or a 6-20R receptacle and appropriate wiring and breaker.

If you are going to install a separate circuit why would you not just hardwire it? People who want to plug a micro inverter into a receptacle usually want to bypass permits and the need to install a separate circuit. They also are unlikely to spend the money for an Enphase inverter.

 

[theoldwizard1]

If you are going to install a separate circuit why would you not just hardwire it?

Least expensive way to have a disconnect !

People who want to plug a micro inverter into a receptacle usually want to bypass permits and the need to install a separate circuit. They also are unlikely to spend the money for an Enphase inverter.

So ...

 

[reader2580]

I'm pretty certain my utility would never approve a receptacle for the required utility disconnect.

 

[dcg9381]

I'm pretty certain my utility would never approve a receptacle for the required utility disconnect.

My utility wouldn't allow the implementation of Rapid Shutdown modules (NEC 2020) in place of exterior, labeled, physical disconnects. The good news is they don't require that you're a licensed electrician, so I'll take it.

 

[mm08822]

My utility wouldn't allow the implementation of Rapid Shutdown modules (NEC 2020) in place of exterior, labeled, physical disconnects. The good news is they don't require that you're a licensed electrician, so I'll take it.

I think the rapid shutdown requirement was from the Fire Dept as they wanted dc conductors dead as close to the panels as possible to further minimze contact with h20..

POCO wants to see a physical set of contacts open.

 

[caleb383]

First thing to double-check is your local utility's net metering rules. Some power companies pay you pennies for extra summer power, so oversizing to 125% doesn't always break even as fast as salesmen promise.

When I was setting up power for my own shop, I almost fell for a huge system I didn't need. I ended up getting a clean breakdown from Emergent Solar Energy just to compare offset vs actual usage before signing anything.

Get the total cost per watt and check the inverter brand. Don't just look at the monthly finance bill, because those 25-year loans often hide massive dealer fees up front

 

[dave*99]

First thing to double-check is your local utility's net metering rules. Some power companies pay you pennies for extra summer power, so oversizing to 125% doesn't always break even as fast as salesmen promise.

Also, get the total cost per watt and check the inverter brand. Don't just look at the monthly finance bill, because those 25-year loans often hide massive dealer fees up front

First thing to check is the dates on the thread.

 

[wyliesdiesels]

First thing to check is the dates on the thread.

thats hilarious

 

[Murby]

Who here has switched to using solar for your house/ shop and what to look out for. We just finished building a new shop at our house and with that out usage has already gone up and it will continue to rise. On top of that our price for that electricity has increased as well, and because it comes from a public company that has to switch from coal/ natural gas to renewable in the next 5 years, the price will continue to increase. We met with a person from a localish company and the 2 people that I met live within 20 minutes of me. They do not offer leasing options, only financing. They do all of the selling, installing, repairs etc inhouse. The panels are from Hyundai and have a 25 year warranty and at the 25 year should still produce 85%. Please give me any insight.
Thanks Brian

Our home has been on solar since 2017. I install solar (for free) for family and friends, and I also build custom off-grid battery backup systems.

So here's the deal with going solar.
1) If you have the property, go for a ground mounted system. If not, then it is what it is. Ground mount systems are more expensive because you have to buy the structure, but they produce quite a bit more power because you can get an exact angle and direction rather than having to just depend on whatever your roof angle is. Ground mount system also run cooler on hot days (air flow under them), and are a lot easier to clean off the snow if you get snow.

2) If you pay a company to install the solar, it really isn't worth it.. The difference is huge. DIY gives you a higher quality system for about 1/3 the cost of having a company do it. The payback time period is MUCH shorter for a DIY system. My payback was 5.1 years when we installed.. the very next year, the power company jacked rates up by 11%.. They did it again 3 years later. Our entire system, including all the nickel and dime ****, paid for itself in 4.5 years. Electric has been free for us ever since.. minus a $9/month meter charge.
Most of these small solar companies are fly-by-night.. They do well when gov is offering rebates and solar is in the news, but as soon as that stuff goes away or fades, a lot of them go out of business.
DIY solar is cheap enough that you shouldn't have to finance it. Our 12kW system cost us about $10k. NEVER lease a system. Every single one of those "Free solar install" programs is a scam.

3) Solar panels are solar panels.. but when it comes to inverters, stick with SMA. If anyone mentions EnPhase, you should run away. Don't fall for the double sided solar garbage.. it's not worth it..

4) Stay away from microinverters and stick to string inverters. Microinverters are more expensive, have a higher failure rate, and are almost always incapable of full panel power. Installers like to push them because they are easier to install. There's nothing really wrong with microinverters for small installs of just a few panels, but for larger systems, I'd stay away. Having to take half your system apart just to fix one unit is not fun.

5) Stay away from anything made in China.. with the exception of the panels themselves.. and in that case, it's okay if they're made in China so long as they are not a Chinese brand.

6) The Germans make the best stuff.. SMA is German.

7) If you're setting up a system that can go off-grid, stay way from the "all in one" inverters. There's a bit of a fad(?) with these companies putting a bunch of blinky blinky lights on their products, led screens, and all kinds of cool high tech looking stuff.. It's all junk.

8) Contact your power company and make sure they have a net-metering agreement.. Make sure you read it.. twice.

9) When you finally place an order, get a couple extra panels to put in storage. They change the panels like they change kitchen storage containers.. What you purchase today will probably not be available in five or six years.. and if someone launches a baseball and cracks a panel, you're going to want to replace it with the same model number panel you already have.. and it will **** if its no longer being sold.

10) Gather up 3 to 5 years of your electric bills and put the energy use into a spreadsheet.. This will help you understand how big of a system you'll need. Then go to https://pvwatts.nlr.gov/ and enter in the specs you're planning.. PvWatts will tell you exactly how much energy those panels will generate each year and each month.. PvWatts is stunningly accurate... They calculated mine to within 1% accuracy on the first year, 0.5% the 2nd year, and 1.5% on the third year. I suggest you over-size your system by about 15% to 20% subject to your net metering rules.
Do not trust the installers to run this math for you.. Most of these idiots don't even know what a kW or a kWh is.

11) Figure out where you want the solar and make sure you know if any trees are going to shade it. 10% shading will result in up to 80% loss of power generation. This is one area where microinverters do have an advantage.

 

[Just_Steve]

Our home has been on solar since 2017. I install solar (for free) for family and friends, and I also build custom off-grid battery backup systems.

So here's the deal with going solar.
1) If you have the property, go for a ground mounted system. If not, then it is what it is. Ground mount systems are more expensive because you have to buy the structure, but they produce quite a bit more power because you can get an exact angle and direction rather than having to just depend on whatever your roof angle is. Ground mount system also run cooler on hot days (air flow under them), and are a lot easier to clean off the snow if you get snow.

2) If you pay a company to install the solar, it really isn't worth it.. The difference is huge. DIY gives you a higher quality system for about 1/3 the cost of having a company do it. The payback time period is MUCH shorter for a DIY system. My payback was 5.1 years when we installed.. the very next year, the power company jacked rates up by 11%.. They did it again 3 years later. Our entire system, including all the nickel and dime ****, paid for itself in 4.5 years. Electric has been free for us ever since.. minus a $9/month meter charge.
Most of these small solar companies are fly-by-night.. They do well when gov is offering rebates and solar is in the news, but as soon as that stuff goes away or fades, a lot of them go out of business.
DIY solar is cheap enough that you shouldn't have to finance it. Our 12kW system cost us about $10k. NEVER lease a system. Every single one of those "Free solar install" programs is a scam.

3) Solar panels are solar panels.. but when it comes to inverters, stick with SMA. If anyone mentions EnPhase, you should run away. Don't fall for the double sided solar garbage.. it's not worth it..

4) Stay away from microinverters and stick to string inverters. Microinverters are more expensive, have a higher failure rate, and are almost always incapable of full panel power. Installers like to push them because they are easier to install. There's nothing really wrong with microinverters for small installs of just a few panels, but for larger systems, I'd stay away. Having to take half your system apart just to fix one unit is not fun.

5) Stay away from anything made in China.. with the exception of the panels themselves.. and in that case, it's okay if they're made in China so long as they are not a Chinese brand.

6) The Germans make the best stuff.. SMA is German.

7) If you're setting up a system that can go off-grid, stay way from the "all in one" inverters. There's a bit of a fad(?) with these companies putting a bunch of blinky blinky lights on their products, led screens, and all kinds of cool high tech looking stuff.. It's all junk.

8) Contact your power company and make sure they have a net-metering agreement.. Make sure you read it.. twice.

9) When you finally place an order, get a couple extra panels to put in storage. They change the panels like they change kitchen storage containers.. What you purchase today will probably not be available in five or six years.. and if someone launches a baseball and cracks a panel, you're going to want to replace it with the same model number panel you already have.. and it will **** if its no longer being sold.

10) Gather up 3 to 5 years of your electric bills and put the energy use into a spreadsheet.. This will help you understand how big of a system you'll need. Then go to https://pvwatts.nlr.gov/ and enter in the specs you're planning.. PvWatts will tell you exactly how much energy those panels will generate each year and each month.. PvWatts is stunningly accurate... They calculated mine to within 1% accuracy on the first year, 0.5% the 2nd year, and 1.5% on the third year. I suggest you over-size your system by about 15% to 20% subject to your net metering rules.
Do not trust the installers to run this math for you.. Most of these idiots don't even know what a kW or a kWh is.

11) Figure out where you want the solar and make sure you know if any trees are going to shade it. 10% shading will result in up to 80% loss of power generation. This is one area where microinverters do have an advantage.

Far be it from me to argue with your experience, but why the hate on enphase? I have an enphase system that run flawlessly. It has IQ8+ micro inverters with 16 standard 400w Q-cell panels. ROI was 7 years but since I converted to whole house heat pump ROI will be down to 5 years.

 

[Murby]

Far be it from me to argue with your experience, but why the hate on enphase? I have an enphase system that run flawlessly. It has IQ8+ micro inverters with 16 standard 400w Q-cell panels. ROI was 7 years but since I converted to whole house heat pump ROI will be down to 5 years.

My only experience is with SMA.. And I too have 400w Q-cells, which are excellent panels.
I spent 10 years (5 previous to install, and 5 after install) on solar forums, watching youtube, and generally investigating.

I've seen too many problems and complaints about Enphase. Customer service is **** and lots of failures. But the biggest issue is that they're sort of a "builders grade" product.

None of that is to say they won't work.. they're not Chinese no-name garbage level stuff.. I've just read about far too many issues.

 

[Sumboodie]

It's not hard to DIY. Unless the installers are fairly cheap, I wouldn't even consider hiring it out.

You built a shop, doing solar will be cake compared to that.

 

[Sumboodie]

My only experience is with SMA.. And I too have 400w Q-cells, which are excellent panels.
I spent 10 years (5 previous to install, and 5 after install) on solar forums, watching youtube, and generally investigating.

I've seen too many problems and complaints about Enphase. Customer service is **** and lots of failures. But the biggest issue is that they're sort of a "builders grade" product.

None of that is to say they won't work.. they're not Chinese no-name garbage level stuff.. I've just read about far too many issues.

I've had Enphase for ~15 years, no issues. Have 18 panels and inverters.
AFAIK it's still all good (sold that place a couple years ago). They are the 1st gen m215 and the house ones were the newer version.
Canadian Solar panels.

Ive considered doing a setup at the new place, but i dunno. I pay about $1400 a year for power.

 

[Murby]

I've had Enphase for ~15 years, no issues. Have 18 panels and inverters.
AFAIK it's still all good (sold that place a couple years ago). They are the 1st gen m215 and the house ones were the newer version.
Canadian Solar panels.

Ive considered doing a setup at the new place, but i dunno. I pay about $1400 a year for power.

My wife has a degree in finance.. she's an accountant/controller.. When we considered solar, she ran a $12k investment through a dozen or so financial models.. 401k, IRA, a reasonably good stock pick, CD's, Bonds, Mutual funds, etc.

Nothing came even close to the returns on solar. Where else can someone invest $12k and have the entire investment returned in five years? And tax free to boot since you're not getting taxable capital gains income, you're saving money.. Every five to six years that one investment returns its original price tag back to our pockets.. tax free, risk free.

And don't even get me started on the power outages.. I just flip a couple switches and the thing goes from grid-tied mode to fully isolated off-grid operation. Although that was an extra $4k investment later on.

 

[Sumboodie]

My wife has a degree in finance.. she's an accountant/controller.. When we considered solar, she ran a $12k investment through a dozen or so financial models.. 401k, IRA, a reasonably good stock pick, CD's, Bonds, Mutual funds, etc.

Nothing came even close to the returns on solar. Where else can someone invest $12k and have the entire investment returned in five years? And tax free to boot since you're not getting taxable capital gains income, you're saving money.. Every five to six years that one investment returns its original price tag back to our pockets.. tax free, risk free.

And don't even get me started on the power outages.. I just flip a couple switches and the thing goes from grid-tied mode to fully isolated off-grid operation. Although that was an extra $4k investment later on.

I only made power about 6 months a year.

 

[Murby]

I only made power about 6 months a year.

I'm in Michigan. January is bad.. not enough power for the home.. February is better, we usually break even. March through October are good as we make enough power for two or three homes.. then in November, we barely brake even, and December is another loss.

 

[Sumboodie]

I'm in Michigan. January is bad.. not enough power for the home.. February is better, we usually break even. March through October are good as we make enough power for two or three homes.. then in November, we barely brake even, and December is another loss.

May-October here. June and July the best.

Excess is wasted, power company buys at like 0.05 a kwhr, sells at. 25

 

[Just_Steve]

I'm in Michigan. January is bad.. not enough power for the home.. February is better, we usually break even. March through October are good as we make enough power for two or three homes.. then in November, we barely brake even, and December is another loss.

My good and bad months pretty much mirror yours.

 

[Murby]

May-October here. June and July the best.

Excess is wasted, power company buys at like 0.05 a kwhr, sells at. 25

Wow.. POCO is just ripping off solar people.

At that price, I would not give them any power at all.. Rig for Net Zero so you don't export squat. And I'd take other steps as well, like becoming hyper energy efficient, going off grid with grid-tie backup, etc.

You're in Alaska? That's tough for solar.. I'd be inclined to build my own wind turbine because the further north you go, the more wind there tends to be.
This guy did a fantastic job and is exactly what I'd do..

 

[mm08822]

We are fortunate in my state where over generation is banked on my account and deducted when another month uses more Kwh. This means I am getting a full price/kwh reduction.

Some states buy back at reduced kwh rates and others even deduct for the distribution component in the pricing.

My system only provides 2/3 of my demand (due to roof size and zoning reqs) so I haven't followed the true-up pricing rates.

 

[Sumboodie]

Wow.. POCO is just ripping off solar people.

At that price, I would not give them any power at all.. Rig for Net Zero so you don't export squat. And I'd take other steps as well, like becoming hyper energy efficient, going off grid with grid-tie backup, etc.

You're in Alaska? That's tough for solar.. I'd be inclined to build my own wind turbine because the further north you go, the more wind there tends to be.
This guy did a fantastic job and is exactly what I'd do..

Wind doesn't pencil out for the cost and maintenance.

 

[dcg9381]

Wow.. POCO is just ripping off solar people.
At that price, I would not give them any power at all.. Rig for Net Zero so you don't export squat. And I'd take other steps as well, like becoming hyper energy efficient, going off grid with grid-tie backup, etc.

My POCO is terribly afraid of "becoming California" despite the 2% residential deployment rate. The policy change and reduction of kWh payback was a direct reflection to discourage the deployment of solar power in residential.

Rig for net zero export is definitely the right call, but older systems (like mine 5 years old) were not designed for use with battery systems, so I have to retrofit. And the amount of batteries required for net-zero ain't cheap.

If you can rig for net-zero export, you can also take advantage of time of day rates to "buy low" and "discharge high". Gotta play the game, but it's expensive up front.

Wind doesn't pencil out for the cost and maintenance.

Agree, I got certified to install wind. As soon as I did, I realized that I never wanted to install wind. Zero callbacks on solar deploys, pretty sure that wouldn't be the case for wind...

But I totally get it in Alaska or other areas.... You do what you can there.

 

[Murby]

Rig for net zero export is definitely the right call, but older systems (like mine 5 years old) were not designed for use with battery systems, so I have to retrofit. And the amount of batteries required for net-zero ain't cheap.

Every grid tied inverter can go fully off grid.. Most off-grid folks use a DC Coupling architecture, so most folks think a system needs to use DC charge controllers and all the other associated stuff.

But any grid tied solar system can go off grid with AC Coupling.. Mine grid tied system isn't any different than anyone else's.. But when I go off grid, I isolate from the grid.. that causes the solar inverters to shut down (which they already are when the power goes off). I fire up the battery backup, which creates a mini-grid with grid quality power. When the solar array's grid tied inverters see this mini-grid, they think the grid is back up and start making power again..
If the solar makes more power than the house needs (which is usually the case most of the day), the battery inverters use the extra juice to charge the batteries.. If the solar array doesn't make enough juice, then the battery inverter uses the batteries to make up for the deficit..

If the sun isn't cooperating, I can plug a gasoline generator into the system and it will charge the batteries and power the house.. and all the while, the grid-tied solar array is adding whatever power it can to the system. Basically, a standard generator, solar array, and the batteries, are all working together to share the house loads and get the batteries charged back up.

The whole thing works seamlessly.... I should note that AC coupling can be (supposed to be) wired so it's automatic.. When the grid goes down, the system is supposed to switch to AC coupling mode instantly and your power never blinks out.. But I didn't want my battery inverters connected to anything when I'm not using them so my switch to off-grid mode is somewhat similar to someone hooking up a portable generator to power their home. I have the physically connect then flip a couple switches to fire the system up.

My system is physically clean.. There's a conduit going between the solar and circuit breaker panel, and one that goes from the battery bank to the breaker panel.. That's it.. no crazy wires, no ugly brackets hanging on a plywood wall.. none of that garbage. Just a box the size of a kitchen fridge next to my breaker box.

 

[dcg9381]

But any grid tied solar system can go off grid with AC Coupling.. Mine grid tied system isn't any different than anyone else's.. But when I go off grid, I isolate from the grid.. that causes the solar inverters to shut down (which they already are when the power goes off). I fire up the battery backup, which creates a mini-grid with grid quality power. When the solar array's grid tied inverters see this mini-grid, they think the grid is back up and start making power again..

That makes sense, but the ability to "switch grid to local" isn't built into most of the consumer based systems that I've seen... Also requires some knowledge of knowing what the hell you're doing.... I suspect systems that can automate this are already advanced enough to be power backups and redundant.

If the solar makes more power than the house needs (which is usually the case most of the day), the battery inverters use the extra juice to charge the batteries.. If the solar array doesn't make enough juice, then the battery inverter uses the batteries to make up for the deficit..

So essentially you've got a grid tie and "local" (isolated) inverter as well as a grid shut off. Curious how you manage the back-feed from the grid tie inverter to the "isolated" inverter.... I have a "power assist" inverter in my Cargo Trailer, but it's advanced enough that I could literally set "feed" preference on it and would only need one inverter.. Albeit a more modern battery/grid tie inverter....

 

[Just_Steve]

That makes sense, but the ability to "switch grid to local" isn't built into most of the consumer based systems that I've seen... Also requires some knowledge of knowing what the hell you're doing.... I suspect systems that can automate this are already advanced enough to be power backups and redundant.

So essentially you've got a grid tie and "local" (isolated) inverter as well as a grid shut off. Curious how you manage the back-feed from the grid tie inverter to the "isolated" inverter.... I have a "power assist" inverter in my Cargo Trailer, but it's advanced enough that I could literally set "feed" preference on it and would only need one inverter.. Albeit a more modern battery/grid tie inverter....

I don't have batteries but my system switches from grid to of grid automatically with a power outage. Doesn't help at night but keeps my heat on and freezer frozen during the day.

Understanding Sunlight Backup system for homeowners | Enphase

enphase.com

 

[Murby]

That makes sense, but the ability to "switch grid to local" isn't built into most of the consumer based systems that I've seen... Also requires some knowledge of knowing what the hell you're doing.... I suspect systems that can automate this are already advanced enough to be power backups and redundant.

All normal grid tied solar inverters, the kind you find on almost every installed grid tied solar system, are capable of operating within an AC coupled off grid system. That's because they're not actually doing anything different. The part of the AC coupled system that is special is the battery inverter, and you're correct, not all battery inverters are capable of this function. SMA SunnyIslands can do it, Outback Radian's can do it, as can many others.. But if you have such a battery inverter, there is nothing that needs to be done to the grid tied inverters.. they can be left untouched. There are grid tied inverter settings that can optionally be modified for smoother operation, but they are not a requirement if the inverter doesn't have them available. Any grid-tied solar inverter can operate in AC coupling mode.. the fact is, that's what they do normally when they're connected to the grid.. They're operating in AC coupling mode.

So essentially you've got a grid tie and "local" (isolated) inverter as well as a grid shut off. Curious how you manage the back-feed from the grid tie inverter to the "isolated" inverter.... I have a "power assist" inverter in my Cargo Trailer, but it's advanced enough that I could literally set "feed" preference on it and would only need one inverter.. Albeit a more modern battery/grid tie inverter....

No.. My solar system has a grid tied solar inverter that pumps juice into the grid just like any other normal grid tied solar inverter sitting under the solar array.. Microinverters can perform the same function. There is nothing special or different about my solar system.

The special part is the battery inverters.. When the grid goes down, the grid gets isolated from the house.. it's similar to how those whole Generac generators work.. a relay opens and the grid is no longer connected to the house. My specific system is set up differently, but the principle is the same. My system is manual.. I have to do it myself because I wanted it that way.. But my system can also be set up to do it automatically within 25ms of the grid going down.

The back feed from the grid tied inverter is managed by the battery inverter. Extra juice, beyond what the house needs, is converted to DC current to charge the batteries. Here is where it gets interesting. There are two ways for this to work.. 1) If the house needs are satisfied AND the batteries are fully charged, AND the grid tied inverter is capable of this operation, the battery inverters will raise the grid frequency from 60hz, to 60.1 hz, then 60.2, then 60.3, etc... When the grid frequency hits 61hz, for every 0.1hz above that, the solar inverters output will decrease by 10%. At 61.5hz, if the grid tied solar inverters want to push 5000 watts, they will only push 2500 watts.
The technical term for this is "Frequency Shift Power Control" Not all grid tied solar inverters can do this, but it doesn't matter because they will all shut down when FSPC hits 62hz.

My AC Coupling has smooth FSPC... that prevents overcharging of the batteries..

2) For for grid tied solar inverters that are not capable of FSPC, they just go into shut down mode.. Not a problem.. as soon as the battery drains a few percentage points, the FSPC will adjust the grid frequency back down and the grid tied solar inverters will start making power again.

If the solar inverters are capable of following FSPC, the operation is smooth and invisible.. If they are not capable of FSPC, it's just an on/off operation.. either way, it works perfectly and your batteries don't care.

 

[dcg9381]

I don't have batteries but my system switches from grid to of grid automatically with a power outage. Doesn't help at night but keeps my heat on and freezer frozen during the day

Interesting. I've always considered "direct solar" power to be so unstable that it can't reliably used as a backup power source. Clouds can swing output 90%. I've seen a few "direct solar" systems, but never worked on one or used one... I've always buffered through batteries.

Thanks for sharing. How much "essential load" are you putting behind these?