Grid Tied Inverter with Limiters

[bedpan]

I have been edumacating myself on solar for the last few months. I originally was going to build a small test bed with one of the cheap aliexpress GTIL inverter and a handful of panels. As I learned more I decided to skip this phase and just go whole hog. I got quotes from solar providers up here in Southern Ontario Canada. Prices seemed to high to me ($35k'ish for 15kW of panels on a 10kW inverter) so I did some more homework and decided I would DIY.
I started contacting the required entities to insure I could legally complete this project. I talked with the ESA as I was told by one installer home owners cannot install solar. ESA told me this is not true, here in Ontario the home owner can do all electrical work. I contacted the township and confirmed what was required and told I need a building permit with an truss engineering report so I have started looking for a company to help with this. I contact hydro one my hydro provider and was told they have no limitation as to who completes the work but I do need approval to backfeed.
So with this I submitted an application to Hydro One to back feed up to 10kW. After almost a month I got a response and was declined to grid connect. A further call to Hydro One and I was told they cannot approve even a small 1kW system for my substation. They tell me there are no plans they are aware of to upgrade my station and as such I cannot backfeed any power.
I plan to continue to appeal the case with hydro and I may reach out to local government officials to see if they can assist at all. In the mean time I back to a Grid Tied with Limiter system.

I think I want to avoid these cheap GTIL 1kW and 2kW inverters. So the question... What options exist in the 3-5kW inverter size with dual CT sensors for split phase power? Something like the Solark would be amazing but price wise is out of my league. What other options exist? I look forward to your suggestions!

 

[fafrd]

I I think I want to avoid these cheap GTIL 1kW and 2kW inverters. So the question... What options exist in the 3-5kW inverter size with dual CT sensors for split phase power? Something like the Solark would be amazing but price wise is out of my league. What other options exist? I look forward to your suggestions!

The major benefit of the GTIL inverters is that they can operate with next to no modification of existing wiring (just a new circuit breaker to feed their energy like any Microinverter or string-inverter-based system).

If you are willing to locate a new ‘box’ between the grid input and your main panel (or your main panel and a critical loads panel), there are a range of Hybrid Inverters that will achieve your aims (such as Solark).

I originally planned to do exactly that with a Magnum PAE or Schneider Conext before the rewiring needed became a showstopper for me.

So I went with a pair of $250 1kW GTILs (one per leg), because they required no changes to existing wiring (and can be removed anytime without loss of house functionality).

If you going with permits you’ll need to stick to UL listed Hybrid inverters which will cost you more (Solark is considered competitive on that market).

If you decide you don’t have the budget for a UL Listed Hybrid, there are much cheaper non-listed Hybrid such as those from GroWatt or MPP solar, but that was the point where I decided if I’m going to have rip everything out if/when I sell the house anyway, the GTILs look like a much better choice.

CT sensors are only a requirement if there is no box between grid and main panel (since any box located there can obviously monitor the current through itself).

The GTILs must rely on CT sensors to monitor import and avoid any export because they are positioned in parallel with the grid and otherwise have no way to monitor grid current…

 

[bedpan]

Ha. Just saw on this thread: https://diysolarforum.com/threads/g...storage-hybrid-csa-ulc-or-esa-approval.30291/
Growatt is not likely approved for Canada with a fairly local seller. Some more reading now.

 

[bedpan]

The major benefit of the GTIL inverters is that they can operate with next to no modification of existing wiring (just a new circuit breaker to feed their energy like any Microinverter or string-inverter-based system).

If you are willing to locate a new ‘box’ between the grid input and your main panel (or your main panel and a critical loads panel), there are a range of Hybrid Inverters that will achieve your aims (such as Solark).

I originally planned to do exactly that with a Magnum PAE or Schneider Conext before the rewiring needed became a showstopper for me.

So I went with a pair of $250 1kW GTILs (one per leg), because they required no changes to existing wiring (and can be removed anytime without loss of house functionality).

If you going with permits you’ll need to stick to UL listed Hybrid inverters which will cost you more (Solark is considered competitive on that market).

If you decide you don’t have the budget for a UL Listed Hybrid, there are much cheaper non-listed Hybrid such as those from GroWatt or MPP solar, but that was the point where I decided if I’m going to have rip everything out if/when I sell the house anyway, the GTILs look like a much better choice.

CT sensors are only a requirement if there is no box between grid and main panel (since any box located there can obviously monitor the current through itself).

The GTILs must rely on CT sensors to monitor import and avoid any export because they are positioned in parallel with the grid and otherwise have no way to monitor grid current…

I like the idea of the GTIL's for the simplicity, but just want something a little larger with some approvals.. I just posted above that Growatt may now be an option as they have a Dual CT clamp accessory you can buy for some of there inverters.

 

[fafrd]

Ha. Just saw on this thread: https://diysolarforum.com/threads/g...storage-hybrid-csa-ulc-or-esa-approval.30291/
Growatt is not likely approved for Canada with a fairly local seller. Some more reading now.

That’s a good list, but as you look through the listed options, you’ll see that they all end up coming in close to or over the Solark.

As far as lower-cost listed offerings, you might want to start tracking this thread: https://diysolarforum.com/threads/s...40v-48v-hybrid-energy-storage-inverter.30249/

 

[Hedges]

Your city permit office will probably approve and sign off a basic grid-tie (backfeed) system. When complete, you've got panels on your roof.
Your utility won't give permission to backfeed. If you swap in a zero-export inverter, they'll never see power going the wrong direction.

SMA also offers zero-export. It would have a Sunny Boy, I think some sort of System Manager from SMA, and a 3rd party box that measures power. I'm not clear on total cost or configuration, hopefully about $1k above the GT PV inverter.

You can add battery storage or battery backup later, but that costs more, probably gets to a price similar to SolArk which already includes it.
Your choice of battery backup system would have to consider what sort of loads (motor starting) you need.

 

[fafrd]

I like the idea of the GTIL's for the simplicity, but just want something a little larger with some approvals.. I just posted above that Growatt may now be an option as they have a Dual CT clamp accessory you can buy for some of there inverters.

Again, if your wiring an inverter such as a Growatt into the current path from/to the grids, presence or absence of CR sensors is secondary.

If you’ve decided you want to stick to listed equipment, you’ll need to either pay the premium or wait until a lower-cost offering from Growatt or Huayu completes the approvals you’re looking for.

Sigineer also has hybrid offerings that have received some approvals, so you may want to check them out: https://www.sigineer.com/product-category/inverter-chargers/ul-listed-inverter-chargers/

As far as ‘a little larger’, the GTILs can easily be cascaded, so you can achieve 2kW of split-phase power with 4 1kW GTILs for ~$1000, 3kW with 6 for ~$1500, or 4kW with 8 for ~$2000.

Because they are connected in parallel with the grid, you don’t need to worry about peak power and only average power consumption.

My 2 1kW GTILs cover 100% of my self consumption except when the electric oven is used (1.5kW / leg when the element is on) or when I get a large-short startup surge from the fridge motor turning on (which gets supplied by the grid).

I’m able to cover well over 90% of my 14kW/day self-consumption using just 2 1kW GTILs…

 

[fafrd]

Your city permit office will probably approve and sign off a basic grid-tie (backfeed) system. When complete, you've got panels on your roof.
Your utility won't give permission to backfeed. If you swap in a zero-export inverter, they'll never see power going the wrong direction.

Wouldn’t it be a lot easier to just get the zero-export Hybrid system permitted?

SMA also offers zero-export. It would have a Sunny Boy, I think some sort of System Manager from SMA, and a 3rd party box that measures power. I'm not clear on total cost or configuration, hopefully about $1k above the GT PV inverter.

That raises a good point that has not been touched on before - any zero-export system is going to be much, much more useful / productive with an attached battery (even a relatively small one).

The OP should probably be including some cost for a battery in his system (if not already done).

You can add battery storage or battery backup later, but that costs more, probably gets to a price similar to SolArk which already includes it.
Your choice of battery backup system would have to consider what sort of loads (motor starting) you need.

Backup battery has not been mentioned. If backup power is needed, that’s going to need a big battery likely y to I become the most expensive component of the system.

Without wanting backup capability, I’ll use my system to illustrate the value of even a small battery.

Average consumption of my fridges is ~350kW with peak consumption of 600W from the single largest fridge when it is ready running.

My GTIL inverter has efficiency of only ~80%, so 440W average and 750W peak consumption from the source of input power to the inverter (solar array or battery).

So if my goal is to run my fridges off of solar for the highest-energy ~8 hours per day, I’d need a big-enough array to generate 750W from 8 or 9am to 4 or 5pm (probably at least 1.5kW if not 2.25kW).

Now let’s use that same 750W array to charging a 1kWh battery. As soon as output from the array reaches 750W, fridge can be powered off of solar, but when fridge cycles off, 750Wh/hour will continue to charge the battery. By the time solar pitot has dropped to 440W, fridge will be powered from bot solar array and battery when on and will replenish battery when off. Once solar power drops down below 440W, battery will stop fully replenishing as fridge continues to duty-cycle but will continue to supply enough energy to power the fridge for well over 2 hours.

Bottom-line is where a 750W array would only power my fridge for the peak 1-2 hours every day, addition of a very-modest 1kWh battery would at least triple if not quadruple that runtime and more importantly, would capture and make use of 100% of solar energy generated rather than wasting over 40% of it (the solar output is wasted when the fridge is not running).

 

[bedpan]

That’s a good list, but as you look through the listed options, you’ll see that they all end up coming in close to or over the Solark.

As far as lower-cost listed offerings, you might want to start tracking this thread: https://diysolarforum.com/threads/s...40v-48v-hybrid-energy-storage-inverter.30249/

Thanks I will have a look through and price some things out..

 

[bedpan]

Your city permit office will probably approve and sign off a basic grid-tie (backfeed) system. When complete, you've got panels on your roof.
Your utility won't give permission to backfeed. If you swap in a zero-export inverter, they'll never see power going the wrong direction.

SMA also offers zero-export. It would have a Sunny Boy, I think some sort of System Manager from SMA, and a 3rd party box that measures power. I'm not clear on total cost or configuration, hopefully about $1k above the GT PV inverter.

You can add battery storage or battery backup later, but that costs more, probably gets to a price similar to SolArk which already includes it.
Your choice of battery backup system would have to consider what sort of loads (motor starting) you need.

I have not seen the option the SMA with Zero export. As you say price wise it may not be the best option but I will have a look and see where we land.

 

[bedpan]

Again, if your wiring an inverter such as a Growatt into the current path from/to the grids, presence or absence of CR sensors is secondary.

If you’ve decided you want to stick to listed equipment, you’ll need to either pay the premium or wait until a lower-cost offering from Growatt or Huayu completes the approvals you’re looking for.

Sigineer also has hybrid offerings that have received some approvals, so you may want to check them out: https://www.sigineer.com/product-category/inverter-chargers/ul-listed-inverter-chargers/

As far as ‘a little larger’, the GTILs can easily be cascaded, so you can achieve 2kW of split-phase power with 4 1kW GTILs for ~$1000, 3kW with 6 for ~$1500, or 4kW with 8 for ~$2000.

Because they are connected in parallel with the grid, you don’t need to worry about peak power and only average power consumption.

My 2 1kW GTILs cover 100% of my self consumption except when the electric oven is used (1.5kW / leg when the element is on) or when I get a large-short startup surge from the fridge motor turning on (which gets supplied by the grid).

I’m able to cover well over 90% of my 14kW/day self-consumption using just 2 1kW GTILs…

Thanks for the info.. I will have to go back and look at my peak usages through out the days and see where I land. We have no one home Monday to Friday through the days which will be the challenge without having batteries of some sort....

 

[bedpan]

Wouldn’t it be a lot easier to just get the zero-export Hybrid system permitted?

That raises a good point that has not been touched on before - any zero-export system is going to be much, much more useful / productive with an attached battery (even a relatively small one).

The OP should probably be including some cost for a battery in his system (if not already done).

Backup battery has not been mentioned. If backup power is needed, that’s going to need a big battery likely y to I become the most expensive component of the system.

Without wanting backup capability, I’ll use my system to illustrate the value of even a small battery.

Average consumption of my fridges is ~350kW with peak consumption of 600W from the single largest fridge when it is ready running.

My GTIL inverter has efficiency of only ~80%, so 440W average and 750W peak consumption from the source of input power to the inverter (solar array or battery).

So if my goal is to run my fridges off of solar for the highest-energy ~8 hours per day, I’d need a big-enough array to generate 750W from 8 or 9am to 4 or 5pm (probably at least 1.5kW if not 2.25kW).

Now let’s use that same 750W array to charging a 1kWh battery. As soon as output from the array reaches 750W, fridge can be powered off of solar, but when fridge cycles off, 750Wh/hour will continue to charge the battery. By the time solar pitot has dropped to 440W, fridge will be powered from bot solar array and battery when on and will replenish battery when off. Once solar power drops down below 440W, battery will stop fully replenishing as fridge continues to duty-cycle but will continue to supply enough energy to power the fridge for well over 2 hours.

Bottom-line is where a 750W array would only power my fridge for the peak 1-2 hours every day, addition of a very-modest 1kWh battery would at least triple if not quadruple that runtime and more importantly, would capture and make use of 100% of solar energy generated rather than wasting over 40% of it (the solar output is wasted when the fridge is not running).

My thought for now was to avoid batteries. I was going to build out 3-5k array/inverter. Base on your previous post I have to look through my data and figure out my peak/average usages for daytime activity. This will help me size the array. With that though I may still oversize with the idea of using the excess to do other things. Kind of like some inverters having the dump loads. Use the excess to heat the house or do some crypto mining.

Regardless of what system I go with ideally it would have the ability to use battery. Again the Sol-Arks seem like a dream machine but are pretty pricey. I will read through some of the suggested threads and do some comparisons and see what I come up with. The simplicity of the 1k GTIL's your using does have a lot of appeal. Really though if I can find a larger split phase in the 3-5kW range the install can be exactly the same other then the addition of one breaker to my panel. My panel is in the garage which makes it quite easy from a wiring side.

 

[Hedges]

I have not seen the option the SMA with Zero export. As you say price wise it may not be the best option but I will have a look and see where we land.

I think it is Data Manager Lite with Ethernet cable to newer Sunny Boy which implements "Zero feed-in". I think the current transformers are connected to a 3rd-party device, but I haven't figured out the details. SMA had to do something for the Hawaii market in particular, because that got closed to new feed-in.

https://files.sma.de/downloads/EDMM-10-DS-en-35.pdf

 

[first class coatings]

Again, if your wiring an inverter such as a Growatt into the current path from/to the grids, presence or absence of CR sensors is secondary.

If you’ve decided you want to stick to listed equipment, you’ll need to either pay the premium or wait until a lower-cost offering from Growatt or Huayu completes the approvals you’re looking for.

Sigineer also has hybrid offerings that have received some approvals, so you may want to check them out: https://www.sigineer.com/product-category/inverter-chargers/ul-listed-inverter-chargers/

As far as ‘a little larger’, the GTILs can easily be cascaded, so you can achieve 2kW of split-phase power with 4 1kW GTILs for ~$1000, 3kW with 6 for ~$1500, or 4kW with 8 for ~$2000.

Because they are connected in parallel with the grid, you don’t need to worry about peak power and only average power consumption.

My 2 1kW GTILs cover 100% of my self consumption except when the electric oven is used (1.5kW / leg when the element is on) or when I get a large-short startup surge from the fridge motor turning on (which gets supplied by the grid).

I’m able to cover well over 90% of my 14kW/day self-consumption using just 2 1kW GTILs…

Hi , Which brand Gtil are you using, and are you happy with them, and for how long have they been working for? thx

 

[fafrd]

Hi , Which brand Gtil are you using, and are you happy with them, and for how long have they been working for? thx

I’ve been using two of these now for 3+ months: https://www.amazon.com/Inverter-Lim...ocphy=9032080&hvtargid=pla-523294429130&psc=1

Happy overall, but efficiency isn’t great (~80%) and when the cooling fans kick-off, they are louder than I’d like.

But as far as offsetting self-consumption without exporting, they are magical, and build quality seems surprisingly good for what I paid..,

 

[first class coatings]

I’ve been using two of these now for 3+ months: https://www.amazon.com/Inverter-Lim...ocphy=9032080&hvtargid=pla-523294429130&psc=1

Happy overall, but efficiency isn’t great (~80%) and when the cooling fans kick-off, they are louder than I’d like.

But as far as offsetting self-consumption without exporting, they are magical, and build quality seems surprisingly good for what I paid..,

Question on the ct clamp/s, Here in arizona, we have 200 amp service- pretty standard, the the power wire for line 1 and line 2 , 220v -240v is probably 0 awg or 2 awg.. are you fitting your ct clamps around similar wire size??? if so do they fit around the wire?, or do you need to open the clamp, and electrical tape the clamp to the wire??? Thx

 

[fafrd]

Question on the ct clamp/s, Here in arizona, we have 200 amp service- pretty standard, the the power wire for line 1 and line 2 , 220v -240v is probably 0 awg or 2 awg.. are you fitting your ct clamps around similar wire size??? if so do they fit around the wire?, or do you need to open the clamp, and electrical tape the clamp to the wire??? Thx

I had no problem clamping the sensor onto my power main wires which are at least 2AWG.

It should be pretty easy to check the inside diameter of the clamps to check whether they will fit your wires.

 

[Cheap 4-life]

I’ve been using two of these now for 3+ months: https://www.amazon.com/Inverter-Lim...ocphy=9032080&hvtargid=pla-523294429130&psc=1

Happy overall, but efficiency isn’t great (~80%) and when the cooling fans kick-off, they are louder than I’d like.

But as far as offsetting self-consumption without exporting, they are magical, and build quality seems surprisingly good for what I paid..,

My tests resulted in an 87% efficiency out of the 2000w GTIL2 inverters being powered by a 60v nominal battery

 

[Cheap 4-life]

Question on the ct clamp/s, Here in arizona, we have 200 amp service- pretty standard, the the power wire for line 1 and line 2 , 220v -240v is probably 0 awg or 2 awg.. are you fitting your ct clamps around similar wire size??? if so do they fit around the wire?, or do you need to open the clamp, and electrical tape the clamp to the wire??? Thx

They sell larger clamps with the same specs

 

[bedpan]

Mind sharing a little more about your setup? Panels, charge controller, battery? Also running the 2000w are you using the CT clamp? Did you modify and add another?

My tests resulted in an 87% efficiency out of the 2000w GTIL2 inverters being powered by a 60v nominal battery