Matching System Components with My Needs

[kennybee]

Hello. I have been researching solar for years and am getting to the point where I need to decide on specifics components. I know general concepts well, but buying components to work to get what I want is making my head spin. I am looking for your experiences who know the products to help me decide.

Back story: I am building a separate pole building next to the existing house/garage that has 200A service. The new garage is built over the underground power line to the house, so it can be easily intercepted to manage power from the grid to the house. I decided to make the new garage optimized for putting solar panels mounted on the roof. I live in far NW Wisconsin, 50 miles straight south of Duluth, MN. I have the roof pitched at 9:12, which gives me a 37 degree angle (ideal for maximum annual power generation here). I have about 1000 sf of south facing roof to mount panels on. We have a Tesla Y and a Chevy Volt. The electric grid in my area is pretty reliable. I want to do a grid tie system as the daylight in the winter is short and frequently overcast. Being so far north, we get an extra half hour of daylight in the summer compared to Chicago and likewise, a half hour less daylight in the winter compared to Chicago. My [semi-irrational] fear is our adversary, China, will hack and take out our electric grid if and when they invade Taiwan and I want to be able to still use the solar system we invested in to run our cars, refrigerator and freezer.

I am favoring buying a pallet (27) of Heliene 460W solar panels (they are manufactured in nearby MN), currently about $4300. Since they are 460W, I am thinking of NOT going with the Enphase Microinverters because they only have a 366W output. There would be more clipping than I would like. So I think I want Tigo Optimizers (with rapid shutdown to comply with NEC requirements) and an inverter capable of handling around 10kw in AC output (or more). No big deal there. The complication is the battery backup. There is an excellent YouTube video that is 9 years old by "Penn State Solar Center" titled "AC Coupled PV Systems" (sorry I was sure if links were allowed to be posted on this forum). I am looking to find out if there are any modern products to continue giving power to the whole house after the grid shuts down. From the video, I like the Outback Power solution or the Magnum Energy solution they mention. But again, would like to know if there is a better system currently. They talk about "Diversion Loads" as a technology that is emerging, but not readily available. I don't think I am interested in a massive battery, at least not yet. Just a small one to get started. I would like to add to that in the future as funds allow. Chances are, I would rarely ever need it. My electric cars can be my unidirectional battery for now. Tesla does not sell the PowerWall in my area.

Long winded, I know. I wanted to paint the full picture. Any suggestions are greatly appreciated. I respect people's experience and knowledge. Thanks!

 

[HighDesertOffgrid]

Plenty of people doing ac coupled systems here. Follow some of those threads to get some pointers.

 

[kennybee]

Very disappointed after taking 20 minutes to type out my situation (people are always complaining that not enough info was posted) and this totally useless response is all I got. Of course I searched the existing threads, but nothing came up that addressed my particular concern. I was looking for suggestions of a whole house style backup and not just a critical loads panel. If there was a suggestion of a modern technology to search for, a keyword, maybe my search results would have come up with something better.

 

[mciholas]

Very disappointed after taking 20 minutes to type out my situation.

I'm another solar newbie, so all of my input comes from research and no actual experience. I'll take a stab at your questions none the less, such is the empowerment of ignorance.

My [semi-irrational] fear is our adversary, China, will hack and take out our electric grid if and when they invade Taiwan and I want to be able to still use the solar system we invested in to run our cars, refrigerator and freezer.

It will be hard to complete your project without some part made in China. Even the supposedly "made in USA" stuff can have lots of Chinese sourced parts in them.

I am favoring buying a pallet (27) of Heliene 460W solar panels (they are manufactured in nearby MN), currently about $4300.

Tell me more about these panels. That seems like a pretty good deal.

Since they are 460W, I am thinking of NOT going with the Enphase Microinverters because they only have a 366W output. There would be more clipping than I would like.

Perhaps. The NMOT rating is 343 watts per panel so maybe not as much clipping as you think. Microinverters have their place and do simplify some things, but are not without costs. They will cost about as much as your panels. They won't backup your house, at least not in any decent way (Enphase does have a "solar backup" system, but it is lame IMO). I am personally favoring a string inverter for many of the features you are trying to get.

So I think I want Tigo Optimizers (with rapid shutdown to comply with NEC requirements) and an inverter capable of handling around 10kw in AC output (or more).

My current leading candidate inverter is an EG4 18KPV. There are other choices that are somewhat similar, but the EG4 18KPV seems like the feature/value leader to me right now.

I am looking to find out if there are any modern products to continue giving power to the whole house after the grid shuts down.

It took me a long time to figure out that is called a hybrid inverter. It is hybrid because it works both as a grid tie inverter and as an off grid inverter.

I finally found a video showing exactly what I wanted, nearly instantaneous switchover from grid to inverter on grid failure. Here it is:

It basically serves as a big UPS.

The 18KPV inverter sits between the solar panels, the grid, the house load, and the battery and moves energy around to make it all work. The solar array is DC coupled (which is more efficient and no clipping).

You still need RSD capability which you can get with Tigo TS4-A-F devices, or TS4-A-S if you want monitoring, or TS4-A-O if you want optimizers.

I don't think I am interested in a massive battery, at least not yet. Just a small one to get started. I would like to add to that in the future as funds allow. Chances are, I would rarely ever need it.

EG4 makes a 14.3 KWH battery (PowerPro). Or you can use rack batteries (EG4 makes those as well as others). You can add more later.

If your grid is reliable, doesn't go out for long periods, then the battery is of little use. If you do have one, though, it handles the nuisance outages and some longer outages. If the sun is shining, the system will use the solar input, power the house, charge the battery with what is left over. A system which tries to backup on solar only, no battery, is likely to be irritating and unstable, so have at least one battery if that is what you are trying to do.

A key question might be what does your utility allow for back feeding your meter? If it is net metering, you get 100% credit for what you push into the grid, then battery storage is not useful for cost savings. You just push when the sun shines, and pull when it doesn't, and just keep the battery topped off for outages.

If net metering isn't available, and more and more places are like that, then a bigger battery may yield more benefits. The strategy then is stored your excess instead of pushing it to the grid, then use that energy during dark periods. Any energy you use locally is 100% credit if you will since you didn't have to buy that from the utility. Any excess you have after charging your battery and powering the house can still be pumped back into the grid and you get something for it.

A larger battery can also keep you powered during an extended outage. Make it big enough, you can go many days without the grid. If the sun shines, it could last a very long time.

I respect people's experience and knowledge.

I have no experience, so everything I said could be wrong and worth what you paid for it.

Mike C.

 

[kennybee]

I'm another solar newbie, so all of my input comes from research and no actual experience. I'll take a stab at your questions none the less, such is the empowerment of ignorance.


It will be hard to complete your project without some part made in China. Even the supposedly "made in USA" stuff can have lots of Chinese sourced parts in them.


Tell me more about these panels. That seems like a pretty good deal.


Perhaps. The NMOT rating is 343 watts per panel so maybe not as much clipping as you think. Microinverters have their place and do simplify some things, but are not without costs. They will cost about as much as your panels. They won't backup your house, at least not in any decent way (Enphase does have a "solar backup" system, but it is lame IMO). I am personally favoring a string inverter for many of the features you are trying to get.


My current leading candidate inverter is an EG4 18KPV. There are other choices that are somewhat similar, but the EG4 18KPV seems like the feature/value leader to me right now.


It took me a long time to figure out that is called a hybrid inverter. It is hybrid because it works both as a grid tie inverter and as an off grid inverter.

I finally found a video showing exactly what I wanted, nearly instantaneous switchover from grid to inverter on grid failure. Here it is:

It basically serves as a big UPS.

The 18KPV inverter sits between the solar panels, the grid, the house load, and the battery and moves energy around to make it all work. The solar array is DC coupled (which is more efficient and no clipping).

You still need RSD capability which you can get with Tigo TS4-A-F devices, or TS4-A-S if you want monitoring, or TS4-A-O if you want optimizers.


EG4 makes a 14.3 KWH battery (PowerPro). Or you can use rack batteries (EG4 makes those as well as others). You can add more later.

If your grid is reliable, doesn't go out for long periods, then the battery is of little use. If you do have one, though, it handles the nuisance outages and some longer outages. If the sun is shining, the system will use the solar input, power the house, charge the battery with what is left over. A system which tries to backup on solar only, no battery, is likely to be irritating and unstable, so have at least one battery if that is what you are trying to do.

A key question might be what does your utility allow for back feeding your meter? If it is net metering, you get 100% credit for what you push into the grid, then battery storage is not useful for cost savings. You just push when the sun shines, and pull when it doesn't, and just keep the battery topped off for outages.

If net metering isn't available, and more and more places are like that, then a bigger battery may yield more benefits. The strategy then is stored your excess instead of pushing it to the grid, then use that energy during dark periods. Any energy you use locally is 100% credit if you will since you didn't have to buy that from the utility. Any excess you have after charging your battery and powering the house can still be pumped back into the grid and you get something for it.

A larger battery can also keep you powered during an extended outage. Make it big enough, you can go many days without the grid. If the sun shines, it could last a very long time.


I have no experience, so everything I said could be wrong and worth what you paid for it.

Mike C.

Hi Mike. Thanks for the info. Do you have a project on the horizon? I will look further into the EG4 inverter. Since my original post I found the Sol-Arc inverter system. It will be good to compare the systems and cost/benefits. I was familiar with STC and expecting about 90% of that for peak conditions, but I wasn't familiar with NMOT (which looks like it is closer to 80%). That is certainly worth considering. Thanks for that. My panels will be fairly optimal in their placement in regards to angle and direction, so I will look into what NMOT will mean for me.

Heliene appears to make a good panel. They are a Canadian owned company with manufacturing in Canada and the USA (in Minnesota). I learned that all the manufacturers have a 25 or 30 year warranty, but the numbers behind that warranty vary. Heliene guarantees 86% output at 25 years. Mission Solar is 84% @25. Silfab Poly panels are 79.5% @30, Solaria is 84% @30. If Heliene had a 30 year warranty, the linear degradation would put it at close to 84% at year 30, for comparison. "ClearEnergyPartners.Store" is selling a pallet of 27, 460W white backsheet half-cut cell panels for $4221 with free shipping. Story of my life, if I have to pay for shipping, it is coming from across the country, if it is free shipping, they are located near me. LOL.

Our grid power is pretty reliable, with only an outage of a couple of hours after a storm every couple of years. So a small battery is all we need, just to be a buffer until I can fill my cars with juice. That is if we are home when the sun it shining. Our power company allows us to sell back at the same rate we buy, until we have a credit for the month. Then the buy back rate drops to only a couple of cents per kWh. So yes, the grid will be my battery for most days, very rarely needing an actual battery unless the world goes to heck.

 

[kennybee]

I looked it up. I like the EG4. Thanks telling me about it.