I want to build a 1200w grid tie solar system that I can plug into the side of my home.

[JWLV]

I was looking at using this exact thing. How would you do what I want to do with it?

You stated that your goal is to save a few bucks on your electrical bill. Going grid-tied is far too complex and expensive for a do-it-yourself.

So the next best thing is to lower your grid electrical usage. By using a seperate air conditioner, such as the Midea U, you can cool just one room instead of the entire house. This should reduce your electrical usage.

If I was doing this, I'd get the 8000 BTU Midea U (for up to 350 sq ft room), two 48-volt 100AH batteries (EG4 Lifepower, Ruixu, etc), a MPPT all-in-one inverter (Growatt, EcoWorthy, etc), and enough solar panels for the amount of sunlight you get in your area.

Some rough estimates on costs:
Midea U -- $400
2x 48V 100AH batteries -- $2800
All-in-one Inverter -- $600
Misc cables and connectors -- $200
Solar Panels -- ??? (you'll probably want at least 1500 watt in solar panels)

Total: $4000 without solar panels

Let's assume you run the air conditioner 12 hours day. The Midea U uses 710 watts according to its specs. So 12 x 710 = 8520 wh per day. Let's round that to 8.5kwh.

* If you intend to run the air conditioner more than 12 hours a day, you'll probably need more batteries and more solar panels

Let's assume your electrical cost is $0.20 per kwh (could be higher or lower in your area). In a day, you'd be saving 8.5kwh, which equals about $1.70 per day. In about 6.5 years, you'll break even on what you spent on all the solar equipment. After 6.5 years, you'll be saving money, as much as $4000 every 6.5 years. That assumes your electricity cost stays the same at $0.20 per kwh. But it's likely electricity costs will probably go up 10% or 20% by then.

 

[rebellyellsolar]

Both available on Amazon.

Get this and make a power cord, it's a 120vac GTIL, works great, $230:

And this gfci plug, $18, it makes it so as soon as power goes off, it stays off, this makes it have better anti-islanding because it won't turn back on until you manually turn it back on:


Now just use whatever solar panels / batteries you want to power the GTIL. It has configurable output limits and a remote CT you can use simple ethernet style cord to attach where ever you want on your breaker panels or power cords / strips. You don't have to use the CT if you don't want to, you can just straight up set a maximum output limit on it.. if you have a consistent household base load.

Wow! thank you! That plug is going to be important!

 

[rebellyellsolar]

You stated that your goal is to save a few bucks on your electrical bill. Going grid-tied is far too complex and expensive for a do-it-yourself.

So the next best thing is to lower your grid electrical usage. By using a seperate air conditioner, such as the Midea U, you can cool just one room instead of the entire house. This should reduce your electrical usage.

If I was doing this, I'd get the 8000 BTU Midea U (for up to 350 sq ft room), two 48-volt 100AH batteries (EG4 Lifepower, Ruixu, etc), a MPPT all-in-one inverter (Growatt, EcoWorthy, etc), and enough solar panels for the amount of sunlight you get in your area.

Some rough estimates on costs:
Midea U -- $400
2x 48V 100AH batteries -- $2800
All-in-one Inverter -- $600
Misc cables and connectors -- $200
Solar Panels -- ??? (you'll probably want at least 1500 watt in solar panels)

Total: $4000 without solar panels

Let's assume you run the air conditioner 12 hours day. The Midea U uses 710 watts according to its specs. So 12 x 710 = 8520 wh per day. Let's round that to 8.5kwh.

* If you intend to run the air conditioner more than 12 hours a day, you'll probably need more batteries and more solar panels

Let's assume your electrical cost is $0.20 per kwh (could be higher or lower in your area). In a day, you'd be saving 8.5kwh, which equals about $1.70 per day. In about 6.5 years, you'll break even on what you spent on all the solar equipment. After 6.5 years, you'll be saving money, as much as $4000 every 6.5 years. That assumes your electricity cost stays the same at $0.20 per kwh. But it's likely electricity costs will probably go up 10% or 20% by then.

the 2800 bucks in batteries was what I was hoping to avoid. Used panels are cheap where I live. Are you certain the grid tie is not doable? The others seem to have found a slightly jank (way better than my idea) solution that involves using grid tie to dump solar into a strip for a media to feed on. Napkin math on parts and efficiency/power delivery from 1500w of solar would be significantly "cheaper" than the full system you graciously put together for me.

 

[cs1234]

Wow! thank you!

Keep in mind, it meets no codes, and if they notice it, you will get in trouble if you don't remove it.

If you plug it directly into a wall outlet (using that GFCI adapter), be sure you don't have other things on that same circuit elsewhere in the building that will cause you to possibly exceed your wiring limits .. you don't want to exceed the current rating on the wiring in your wall ?. If you don't know how to figure out what circuit various things in your house are on, I would suggest getting a "circuit breaker finder" on Amazon.

 

[JWLV]

the 2800 bucks in batteries was what I was hoping to avoid. Used panels are cheap where I live. Are you certain the grid tie is not doable? The others seem to have found a slightly jank (way better than my idea) solution that involves using grid tie to dump solar into a strip for a media to feed on. Napkin math on parts and efficiency/power delivery from 1500w of solar would be significantly "cheaper" than the full system you graciously put together for me.

I really can't comment on grid-tie. I know that I'm not qualified to do so and any DIY setup is not going to be up to code in Nevada (where I live). For me personally, I'm not even going to attempt going grid-tie.

 

[JWLV]

the 2800 bucks in batteries was what I was hoping to avoid. Used panels are cheap where I live. Are you certain the grid tie is not doable? The others seem to have found a slightly jank (way better than my idea) solution that involves using grid tie to dump solar into a strip for a media to feed on. Napkin math on parts and efficiency/power delivery from 1500w of solar would be significantly "cheaper" than the full system you graciously put together for me.

BTW, one huge benefit of my suggested setup is if your area is prone to power failures, you'll be living large in a nice cool room ? when the rest of the neighborhood is sweating it out ? in a blackout.

And during the winter, if you're not using the air conditioner, you can plug in other devices, such as a TV, computer, a microwave oven.

 

[rebellyellsolar]

Keep in mind, it meets no codes, and if they notice it, you will get in trouble if you don't remove it.

If you plug it directly into a wall outlet (using that GFCI adapter), be sure you don't have other things on that same circuit elsewhere in the building that will cause you to possibly exceed your wiring limits .. you don't want to exceed the current rating on the wiring in your wall ?. If you don't know how to figure out what circuit various things in your house are on, I would suggest getting a "circuit breaker finder" on Amazon.

understood. Is there a unit that does slightly more watts? The media 12000btu does 1300 ish watts and that's where I'm trying to get to. Or would you recommend I eat the other 200 ish so I can be sure I'm not backfeeding.

 

[rebellyellsolar]

BTW, one huge benefit of my suggested setup is if your area is prone to power failures, you'll be living large in a nice cool room when the rest of the neighborhood is sweating it out in a blackout.

And during the winter, if you're not using the air conditioner, you can plug in other devices, such as a TV, computer, a microwave oven.

Your setup is definitely on my mind and I appreciate your candor and help. If you wouldn't mind, could you design a 1500w system as cheaply as possible for me to compare?

 

[zanydroid]

And this gfci plug, $18, it makes it so as soon as power goes off, it stays off, this makes it have better anti-islanding because it won't turn back on until you manually turn it back on:

I don't get how the GFCI helps with anti-islanding. Or is this some kind of custom function for power outages?

That still doesn't guarantee identical anti-islanding to UL1741 standards (there's 10 or so standard "algorithms")

Does the GTIL work battery-less? Because if you added a battery you could also just go with a AIO (for more $$ because surge)

I was looking at using this exact thing. How would you do what I want to do with it?

This reduces the amount of electricity you need and would have lower startup surge ("surge when you turn it on"). However it may have harder power factor ("[small] surge on every cycle") for the inverter to handle. A GTIL doesn't care about either surge nor power factor since the grid will compensate.

where would I put the limiter clamp to avoid this issue

Better to read the instructions on the GTIL/from a GTIL tutorial thread. The clamp needs to be put around an individual conductor. It needs to be placed with the correct polarity. And then clamp meter readings are taken (individual conductor) at probably 3-4 places in the setup, during various operating modes. Need to write out or steal a testplan.

 

[rebellyellsolar]

I don't get how the GFCI helps with anti-islanding. Or is this some kind of custom function for power outages?

That still doesn't guarantee identical anti-islanding to UL1741 standards (there's 10 or so standard "algorithms")

Does the GTIL work battery-less? Because if you added a battery you could also just go with a AIO (for more $$ because surge)


This reduces the amount of electricity you need and would have lower startup surge ("surge when you turn it on"). However it may have harder power factor ("[small] surge on every cycle") for the inverter to handle. A GTIL doesn't care about either surge nor power factor since the grid will compensate.


Better to read the instructions on the GTIL/from a GTIL tutorial thread. The clamp needs to be put around an individual conductor. It needs to be placed with the correct polarity. And then clamp meter readings are taken (individual conductor) at probably 3-4 places in the setup, during various operating modes. Need to write out or steal a testplan.

I would really appreciate a test plan.

 

[zanydroid]

be sure you don't have other things on that same circuit elsewhere in the building that will cause you to possibly exceed your wiring limits .. you don't want to exceed the current rating on the wiring in your wall

This is definitely ideal and the most code compliant way to do it. But it's hard to achieve in practice because there's going to be other receptacles in the same room probably on that circuit, and implies that extension cords are "run all over the room" to plug into the GTIL side of the setup. Alternatively the GTIL could be tied to the first receptacle on a chain, and then everything after that one in the house is downstream of GTIL.

This gets heavily into the "git gud at being a literal electrician" territory to get something really safe. And unfortunately you can have unsafe setups that work. Not sure what the correct advice is other than git gud, I think this is pretty hard to explain or learn correctly in a cliff notes way.

The GTIL limiter if set up correctly is supposed to defend against this, but it is not bulletproof and there's likely no cheap device that will alarm and open the circuit.

 

[rebellyellsolar]

This is definitely ideal and the most code compliant way to do it. But it's hard to achieve in practice because there's going to be other receptacles in the same room probably on that circuit, and implies that extension cords are "run all over the room" to plug into the GTIL side of the setup. Alternatively the GTIL could be tied to the first receptacle on a chain, and then everything after that one in the house is downstream of GTIL.

This gets heavily into the "git gud at being a literal electrician" territory to get something really safe. And unfortunately you can have unsafe setups that work. Not sure what the correct advice is other than git gud, I think this is pretty hard to explain or learn correctly in a cliff notes way.

The GTIL limiter if set up correctly is supposed to defend against this, but it is not bulletproof and there's likely no cheap device that will alarm and open the circuit.

I'm good with "it's safe enough its not going to catch fire or kill you" if we can get me there.

 

[rebellyellsolar]

Is there something I could do to block/stop the power strips line going into the wall to physically prevent grid feedback. Like, in only, no out?

 

[JWLV]

understood. Is there a unit that does slightly more watts? The media 12000btu does 1300 ish watts and that's where I'm trying to get to. Or would you recommend I eat the other 200 ish so I can be sure I'm not backfeeding.

The Midea U 12K BTU's specs say it uses 1140 watts.

The solar build would be almost the same. Just add one more 48v 100AH battery, and probably 2000 watts of solar panels instead of 1500 watts.

 

[rebellyellsolar]

The Midea U 12K BTU's specs say it uses 1140 watts.

The solar build would be almost the same. Just add one more 48v 100AH battery, and probably 2000 watts of solar panels instead of 1500 watts.

I see, thank you.

 

[zanydroid]

I would really appreciate a test plan.

I don't really feel comfortable providing one. I'll give feedback relative to one that exists if posted.

Is there something I could do to block/stop the power strips line going into the wall to physically prevent grid feedback. Like, in only, no out?

No, that requires electronics.

The L (Limiter) part of the GTIL does that. But if you set it up wrong it will do the wrong thing. And this won't solve anti-islanding if GTIL cocked it up.

Even if there's no net power going to the grid, there will still be voltage being put on those wires, and that voltage is enough to cause a safety hazard in an island situation.

With proper legal to install listed equipment for the majority of equipment all the safety is handled within the inverter.

 

[rebellyellsolar]

Understandable. If the power goes out Ill just unplug the thing or switch it to a regular inverter and batteries. I will be using that power cut off device also, as added protection.

 

[cs1234]

I don't get how the GFCI helps with anti-islanding. Or is this some kind of custom function for power outages?

That still doesn't guarantee identical anti-islanding to UL1741 standards (there's 10 or so standard "algorithms")

It isn't going to meet the real anti-islanding specs, in that it isn't going to wait x minutes before coming back online, monitor for certain quality conditions, etc.. What the GFCI does is simply cut the power after you have a power outage. This will ensure linemen are kept safe, it is now off. Sure, it would not have come back on by itself until power was restored and "working" anyway, but I would rather be safe than sorry, and if power outages are occurring, I'll turn it back on after everything seems to be good again.

Does the GTIL work battery-less? Because if you added a battery you could also just go with a AIO (for more $$ because surge)

Yes, it will work directly from solar panels, or any DC source such as batteries.

 

[rebellyellsolar]

It isn't going to meet the real anti-islanding specs, in that it isn't going to wait x minutes before coming back online, monitor for certain quality conditions, etc.. What the GFCI does is simply cut the power after you have a power outage. This will ensure linemen are kept safe, it is now off. Sure, it would not have come back on by itself until power was restored and "working" anyway, but I would rather be safe than sorry, and if power outages are occurring, I'll turn it back on after everything seems to be good again.


Yes, it will work directly from solar panels, or any DC source such as batteries.

I absolutely do not want to hurt anyone. I'm just trying to get some cheap solar juice and turn it into cold.

 

[cs1234]

This is definitely ideal and the most code compliant way to do it. But it's hard to achieve in practice because there's going to be other receptacles in the same room probably on that circuit, and implies that extension cords are "run all over the room" to plug into the GTIL side of the setup. Alternatively the GTIL could be tied to the first receptacle on a chain, and then everything after that one in the house is downstream of GTIL.

This gets heavily into the "git gud at being a literal electrician" territory to get something really safe. And unfortunately you can have unsafe setups that work. Not sure what the correct advice is other than git gud, I think this is pretty hard to explain or learn correctly in a cliff notes way.

The GTIL limiter if set up correctly is supposed to defend against this, but it is not bulletproof and there's likely no cheap device that will alarm and open the circuit.

You would want to check all the outlets in your building to know what outlets are on what. It will take some time, but it's worth knowing anyway. I'm sure most of us here on the forum know exactly what outlets and hardwired devices are on what circuits on our breakers.

If the GTIL is plugged into a strip, and the air conditioner is on that same strip, then it's likely not going to be an issue for OP anyway.. as any power added to the strip is going to be sucked up directly by the air conditioner in almost all situations and he shouldn't be exceeding any current limitations in the in wall wiring.