Planning to reduce electric bill by solar push, no feed back to grid. Daylight hours only.

[roadrunner]

Here's my thoughts, I have a swamp cooler to cool my home (mobile home), it uses 222 watts when running on low, 120 volt, 440 watts on high.
Fridge uses 125 watts when it kicks on, 4.24 KWH in 48 hours time, no big deal.
I want to purchase 2x 100 watt panels, and a 600 watt, grid tie inverter, with a voltage of DC 11 to 32 volt input.

The panels will have a VMP of around 18 volt per panel,
So i can wire panels in parallel to keep vmp at 18volts.
Then, build a suicide cord, to run from inverter to a plug in 15amp breaker power strip. The one that has breaker on top of power strip.
This would plug into the same 120 volt outlet that my swamp cooler is plugged into, which is on the main panel with a breaker.

So, my scenario would be this, get up, and turn cooler on, then switch on circuit breaker on power strip,
This way, no current will back feed to grid because my 2 panels should not put out more than 200 watts even on a perfect day, which never will be because they will be flat mounted on my shed roof.

Now when the sun goes down, i will loose power and then just turn off breaker on power strip. Hopefully i don't forget to shut off breaker,so it doesn't back feed in the morning.
I have been installing solar panel grid tie syastems for 6 years and am a res and comm electrician, so i know all the no don't do that suicide cord, ect.
I have also thought of building a small gfci plug in box for this setup instead of using a power strip.
Just trying to lower my monthly summer bill because of the cooler, that"s it, if i can save 50 bucks a month im good, and not get caught.
The other way might be to see about wills video on that solar setup with the 12 volt inverter that doesn't back feed.
The other reason for doing this is to have a battery backup for emergency's. Also.

 

[Hedges]

Don't do the suicide cord. If you need that, not using the right hardware and in danger of killing your inverter and your friendly local lineman.

Sure, put a power plug on a UL-1741 inverter if you want. They say not to, but it would provide the right connections. I've done it to test. The plug will never be hot when unplugged, and the inverter is designed to interact with the grid. That's not a suicide cord because it isn't double-ended male, and no exposed prongs are ever hot.

You could put the 600W grid-tie inverter wired into the motor of your swamp cooler. Then when you turn the cooler on, the inverter comes up.
Are you sizing it so it will exceed swamp cooler draw, but not average refrigerator draw? In that case it can backfeed through the swamp cooler's switch.

If you feed the inverter with two sets of PV panels, some facing SE and some SW, power output will be more flat during the day.

Other way to go is a zero-backfeed setup. Either current sense clamps at your utility connection, or a hybrid that will add PV/battery power to AC input to power AC output but without backfeed. I know of some expensive solutions, just not sure which brands have something inexpensive.

Use a timer or light sensor to turn refrigerator off at night. Then it'll draw all its power during the day when PV is working, and you can have more panels.

 

[Forbisher]

200 watts of panels at 6 sun hours per day is 1200 watts

1.2Kw per day x 30 days is 36Kw a month.

My cost per kwh from 8am to 4pm is 12 cents Kwh
36kwh x 12 cents is $4.32 a month savings.

$50 power at 12 cents Kwh is 416 Kwh

Here's my thoughts, I have a swamp cooler to cool my home (mobile home), it uses 222 watts when running on low, 120 volt, 440 watts on high.
Fridge uses 125 watts when it kicks on, 4.24 KWH in 48 hours time, no big deal.
I want to purchase 2x 100 watt panels, and a 600 watt, grid tie inverter, with a voltage of DC 11 to 32 volt input.

The panels will have a VMP of around 18 volt per panel,
So i can wire panels in parallel to keep vmp at 18volts.
Then, build a suicide cord, to run from inverter to a plug in 15amp breaker power strip. The one that has breaker on top of power strip.
This would plug into the same 120 volt outlet that my swamp cooler is plugged into, which is on the main panel with a breaker.

So, my scenario would be this, get up, and turn cooler on, then switch on circuit breaker on power strip,
This way, no current will back feed to grid because my 2 panels should not put out more than 200 watts even on a perfect day, which never will be because they will be flat mounted on my shed roof.

Now when the sun goes down, i will loose power and then just turn off breaker on power strip. Hopefully i don't forget to shut off breaker,so it doesn't back feed in the morning.
I have been installing solar panel grid tie syastems for 6 years and am a res and comm electrician, so i know all the no don't do that suicide cord, ect.
I have also thought of building a small gfci plug in box for this setup instead of using a power strip.
Just trying to lower my monthly summer bill because of the cooler, that"s it, if i can save 50 bucks a month im good, and not get caught.
The other way might be to see about wills video on that solar setup with the 12 volt inverter that doesn't back feed.
The other reason for doing this is to have a battery backup for emergency's. Also.

 

[roadrunner]

Thanks, wont back feed because inverter is grid tie, if it loses voltage it shuts off, so no current going through it, now if its battery power and i don't shut of main breaker then it will back feed.
I am only sizing to counter act some of the cooler motor draw, since it uses 222 watts on low, this setup should never go over 200 watts, even on a great day, as it wont be 90% to the sun, it might be close in the summer, but only for like 2-3 months, i live in Arizona, middle of state.

Plus, becaus of the heat, and panel percentage, should never get 100% efficiency. so at less than 200 watts, even on low speed it still should over power my cooler, and on high i know it wont, which is what its usally on in summer from 10 am to 3 pm. On high it use 440 some watts.
I tested with my KW meter.
Ill look into the inverter you suggested, and the one will suggested in his video about the 12 volt easy setup.Ill look into zero back feed inverters

 

[roadrunner]

200 watts of panels at 6 sun hours per day is 1200 watts

1.2Kw per day x 30 days is 36Kw a month.

My cost per kwh from 8am to 4pm is 12 cents Kwh
36kwh x 12 cents is $4.32 a month savings.

$50 power at 12 cents Kwh is 416 Kwh

What im thinking is if i can run my swamp cooler off of just 2 solar panels, for 4 hours a day, and save 25 dollars a month it would worth it, since my swamp cooler would only be using 40 watts an hour maybe, or am i figuring this out wrong

 

[Forbisher]

What im thinking is if i can run my swamp cooler off of just 2 solar panels, for 4 hours a day, and save 25 dollars a month it would worth it, since my swamp cooler would only be using 40 watts an hour maybe, or am i figuring this out wrong

Your 200 watts of panels getting 6 sun hours every day for a month will save you a big $4.32

How much do you pay per kwh?
What is your location to figure your solar insolation?
How are you gonna save $25 month with only 200 watts panels?

 

[Hedges]

What is your utility rate?
Swamp cooler consumes 0.2kW or 0.4kW.
If I pay $0.20/kWh, that's $0.04 or $0.08/hour, $0.40 or $0.80 per 10 hour day. (PV panel produces 5 hours effective output)
So the swamp cooler might cost you $12 or $24 per month and you'll need 400W or 800W PTC (500W or 1000W STC) of panels suitably oriented.
(flat on roof may not be bad in summer for your location.)

Now, 1000W of panels can be had for $200, and maybe you use your swamp cooler 6 months of the year, so panels might pay for themselves in 1.33 years (but need to pay for electronics too.)

Similar numbers to what "Փփքխմպ" said, except I expanded your PV array 5x to match load and got 5x the savings.

 

[fafrd]

Here's my thoughts, I have a swamp cooler to cool my home (mobile home), it uses 222 watts when running on low, 120 volt, 440 watts on high.
Fridge uses 125 watts when it kicks on, 4.24 KWH in 48 hours time, no big deal.
I want to purchase 2x 100 watt panels, and a 600 watt, grid tie inverter, with a voltage of DC 11 to 32 volt input.

The panels will have a VMP of around 18 volt per panel,
So i can wire panels in parallel to keep vmp at 18volts.
Then, build a suicide cord, to run from inverter to a plug in 15amp breaker power strip. The one that has breaker on top of power strip.
This would plug into the same 120 volt outlet that my swamp cooler is plugged into, which is on the main panel with a breaker.

So, my scenario would be this, get up, and turn cooler on, then switch on circuit breaker on power strip,
This way, no current will back feed to grid because my 2 panels should not put out more than 200 watts even on a perfect day, which never will be because they will be flat mounted on my shed roof.

Now when the sun goes down, i will loose power and then just turn off breaker on power strip. Hopefully i don't forget to shut off breaker,so it doesn't back feed in the morning.
I have been installing solar panel grid tie syastems for 6 years and am a res and comm electrician, so i know all the no don't do that suicide cord, ect.
I have also thought of building a small gfci plug in box for this setup instead of using a power strip.
Just trying to lower my monthly summer bill because of the cooler, that"s it, if i can save 50 bucks a month im good, and not get caught.
The other way might be to see about wills video on that solar setup with the 12 volt inverter that doesn't back feed.
The other reason for doing this is to have a battery backup for emergency's. Also.

You should look into a GTIL inverter: https://www.amazon.com/gp/aw/d/B07GC53QBD

They were designed for precisely your application (and are magical when you see them in action).

 

[roadrunner]

Your 200 watts of panels getting 6 sun hours every day for a month will save you a big $4.32

How much do you pay per kwh?
What is your location to figure your solar insolation?
How are you gonna save $25 month with only 200 watts panels?

we have on peak and off peak hours, we have to pick a plan,
so i choose to have my high on peak from 3pm to 6 pm. which is better because of the Az heat than 1-3.
so, my rate for Jan 2021=$1.52, 19KWH, and Feb 2021=$1.11...@ 14 KWH, and in Feb of 2020,$2.35,,,,,18 KWH,, this month my on peak was $4.88,,,, and my off peak was $26.27,,,,,,monthly service charge of $20.,,,,,my bill says 46kwh, and off peak,,,,,356 for a total of 402, it doesnt have a base amount of or per kwh. because it changes whether im off or on peak. Phoenix, az

 

[roadrunner]

What is your utility rate?
Swamp cooler consumes 0.2kW or 0.4kW.
If I pay $0.20/kWh, that's $0.04 or $0.08/hour, $0.40 or $0.80 per 10 hour day. (PV panel produces 5 hours effective output)
So the swamp cooler might cost you $12 or $24 per month and you'll need 400W or 800W PTC (500W or 1000W STC) of panels suitably oriented.
(flat on roof may not be bad in summer for your location.)

Now, 1000W of panels can be had for $200, and maybe you use your swamp cooler 6 months of the year, so panels might pay for themselves in 1.33 years (but need to pay for electronics too.)

Similar numbers to what "Փփքխմպ" said, except I expanded your PV array 5x to match load and got 5x the savings.

cant do it, i live in a trailer park and by their rules cant have anything out side on trailer, or anything on roof but a swamp cooler or air con. my swamp cooler is on side of house in middle of trailer in kitchen and living room window, i can hide 2 small panels on my shed roof which is behind my trailer, and is flat, so hard to tell anything is up there especially a flat panel thats only a 1.5 inch thick. and 38 inch x 29 inch.

 

[roadrunner]

You should look into a GTIL inverter: https://www.amazon.com/gp/aw/d/B07GC53QBD

They were designed for precisely your application (and are magical when you see them in action).

thanks, ill go look at it now, thank you, that looks nice and just what i need, i could wire 2 panels in series and get the voltage it needs, even with just 100 watt panels. instead of me wiring the 2 panels in parallel for the other inverter i was looking at amazon.

Not An Affiliate Link

https://www.amazon.com/dp/B071F5XJMD/?coliid=I2QY4JUM4SME2P&colid=22IB6U5ZOK206&psc=1&ref_=lv_ov_lig_dp_it

 

[fafrd]

thanks, ill go look at it now, thank you, that looks nice and just what i need, i could wire 2 panels in series and get the voltage it needs, even with just 100 watt panels. instead of me wiring the 2 panels in parallel for the other inverter i was looking at amazon.

https://www.amazon.com/dp/B071F5XJMD/?coliid=I2QY4JUM4SME2P&colid=22IB6U5ZOK206&psc=1&ref_=lv_ov_lig_dp_it

Yes, it will control your panels to extract maximum DC power and then convert that DC power to AC to offset your consumption (up to the 1kW limit of its power).

If you are feeding it with 2 100W panels, it will max out at 200W of power.

The sensor wraps around your incoming grid leg and monitors net consumption - it will generate enough power to offset your consumption but will limit itself from generating any additional power which would get exported.

It literally plugs right into a 120V socket to feed its offsetting-power into your grid - AC wiring is trivially easy and it’s just the DC wiring of the panels where you need to make sure you get things right.

 

[roadrunner]

This where i got the idea, Wills video,

The panels i am looking at are 100 watts,
vmp 17v, 5.89 current imp, voc is 20.32v mono 15x4 equals 60 cells, roughly 34x27 inches

 

[roadrunner]

Actually, the larger inverter, compared to the 600 watt i was looking at for $85 dollars, the one fafrd posted might be a better choice for the money,

 

[Forbisher]

cant do it, i live in a trailer park and by their rules cant have anything out side on trailer, or anything on roof but a swamp cooler or air con. my swamp cooler is on side of house in middle of trailer in kitchen and living room window, i can hide 2 small panels on my shed roof which is behind my trailer, and is flat, so hard to tell anything is up there especially a flat panel thats only a 1.5 inch thick. and 38 inch x 29 inch.

Ok you live in Phoenix which is hell on earth.
Even at 7 sun hours a day for only 200 watts panels that is 1.4Kwh per day and Only saving 42Kwh per month if you get 7 hours Every day for how many months a year?
42Kwh at my high rate of 27 cents Kwh (4pm to 9pm) is a bigley $11.34 saving per month.

Add up the cost of 2 100 watt panels plus the inverter, etc.
What's your pay off time?

 

[roadrunner]

i posted my monthly bill results, and at $1.11 per kwh, even for 2 hours a day equals $60 dollars a month, and cost would be $150 for 2 panels, free ship. $85 dollar inverter,free ship, thats it, i am an ex electrician and solar installer, i have all tools, and wire, and solar clamps, ect. i run my swamp cooler for 6 mos out of the year, so thats $360 dollars, my cost is actually zero because im using the covid stimulus check we get for free,

 

[Hedges]

Rates of $1.11/kWh certainly make a difference.

With your panels flat, their peak output will be at noon. When the sun is 45 degrees off to one side around 3:00 PM, output will be 0.7x as much.
It would be more optimum if they were aimed around 4:00 PM sun, for peak rates 3:00 to 6:00 PM. (I aimed mine at 2:00 PM for Noon to 6:00 PM peak). But you have to keep the hidden?

Some panels put out 50% more power for a given area than others, so compare size and wattage.

If you do get an inverter and battery to run swamp cooler during the peak hours, that could save money.

PV could help charge it earlier, but isn't necessary. How much do you charge for off-peak power?
Use a timer to turn off fridge during peak. How about water heater, gas or electric?

 

[Forbisher]

i posted my monthly bill results, and at $1.11 per kwh, even for 2 hours a day equals $60 dollars a month, and cost would be $150 for 2 panels, free ship. $85 dollar inverter,free ship, thats it, i am an ex electrician and solar installer, i have all tools, and wire, and solar clamps, ect. i run my swamp cooler for 6 mos out of the year, so thats $360 dollars, my cost is actually zero because im using the covid stimulus check we get for free,

What you posted of your monthly bills was incomprehensible.
No way you are paying $1.11 per Kwh or would save that much from 2 100 watt panels.
How much is your total bill per month?

200 watts panels only generates 1.4Kwh a day and that's mainly in the peak hours.

Ummmh even if you use "free" stimulus money thats still real money that you could have spent on drugs or booze. Haha

 

[Forbisher]

Rates of $1.11/kWh certainly make a difference.

No way is he paying $1.11 Kwh in Phoenix.

What is the Average Electric Bill in Phoenix? |
The average electricity rate in Arizona is 12.20 cents per kWh, that's an increase of 4.6% since February of 2017.
@snoobler lives in Arizona

 

[snoobler]

@snoobler sure does.

SRP winter rates (cents):

9.5/kWh on-peak
6.9/kWh off-peak

Peak summer rates:

24.1/kWh on-peak
7.3/kWh off-peak

They pay 2.8/kWh for exported solar...

He's talking about total dollar amounts for on peak and off peak kWh amounts.