Solar panels mounted on roof, questions about wiring and proper mounting

[joesmith123]

EG4, SOK, Trophy are some of the ones I would recommend. Or you can build your own and save a little. There are plenty of DIY battery experts on here. I'm not one of them. Lol

I see that you have those 48 volt eg4 lifepower batteries

Question: Do you have those batteries hooked up in parallel?

Also I see you have 2 mpp lv6548 units

Those are the same as the one I have

And I see you have 32 solar panels

With your setup, are you able to store enough energy to run AC and a fridge overnight?

 

[joesmith123]

EG4, SOK, Trophy are some of the ones I would recommend. Or you can build your own and save a little. There are plenty of DIY battery experts on here. I'm not one of them. Lol

EG4 | LifePower4 Lithium Battery | 48V 100AH | Server Rack Battery

The EG4 Lithium battery 51.2V (48V) 5.12kWh with 100AH internal BMS is one of the best server rack battery options money can buy! Composed of (16) UL listed prismatic 3.2V cells in series which have been tested at 7,000 deep discharge cycles to 80% DoD - fully charge and discharge this battery...

solarsovereign.com

Those batteries, just for 1 of those, is $1400

And you have 12 of them?

 

[joesmith123]

13 panels in parallel using your 9 amp spec from before would give you a string at 117 amps. This is not even close to practical. Most of the inverters that you would consider are going to max out at 18a to 25a per string.

5 strings - how many inverters are you planning and how many MPPTs do they have?

Tell me a setup that would be practical to make this happen

I do want to go grab the solar panels and get those mounted while I figure out the batteries/inverter/etc

Attached are pictures of the exact solar panels

Will those ribbracket S-5 work for these solar panels?

Before spending $6 a piece and waiting on shipping, it would help if you guys give input

Thank you so much for all the info

 

[joesmith123]

I arranged to go get the solar panels from the seller tomorrow late afternoon

I am thinking of ordering those brackets now, just to get them on the way,

But i am still waiting on yalls response to the question:

Will those brackets work for these solar panels?

 

[Hedges]

I have similar polysilicon panels from Sharp. Some degraded more than others.
I don't know if that occurred in 17 years in negative-ground PV array, or 1 year in ungrounded transformerless setup.
Someone said Sharp recalled and replaced bad panels.

Since you've got them, try to sort for performance and use similar current panels in a given string.

Voc and Isc do NOT always tell the story. I had some with decent Isc, yet Vmp & Imp showed severe reduction. I tested them into resistive loads.

I arranged to go get the solar panels from the seller tomorrow late afternoon

Oh, you DON'T have those panels yet. Think twice, make sure you're not blowing money and labor on a bunch of degraded ones. How much per watt are you going to pay?

Lots of detail here:

Measuring PV panel performance

I suppose I could buy a solar panel tester like Will reviewed, but that doesn't feel DIY enough to me. Besides, I'm a cheapskate, and I try to do things in the most difficult (and expensive if the equipment wasn't on hand) way. I'm presently working on an underperforming string of Sharp 165W...

diysolarforum.com

 

[joesmith123]

I am tremendously excited for this project

Imagine living on a generator for a year, diagnosing it, coming home to a fridge thats been off for hours, going to get fuel for it at night, babysitting and constant upkeep, changing the oil on it, etc

Imagine if you had all these burdens, and then there might be a way to eliminate all of them

 

[joesmith123]

I have similar polysilicon panels from Sharp. Some degraded more than others.
I don't know if that occurred in 17 years in negative-ground PV array, or 1 year in ungrounded transformerless setup.
Someone said Sharp recalled and replaced bad panels.

Since you've got them, try to sort for performance and use similar current panels in a given string.

Voc and Isc do NOT always tell the story. I had some with decent Isc, yet Vmp & Imp showed severe reduction. I tested them into resistive loads.



Oh, you DON'T have those panels yet. Think twice, make sure you're not blowing money and labor on a bunch of degraded ones. How much per watt are you going to pay?

Lots of detail here:

Measuring PV panel performance

I suppose I could buy a solar panel tester like Will reviewed, but that doesn't feel DIY enough to me. Besides, I'm a cheapskate, and I try to do things in the most difficult (and expensive if the equipment wasn't on hand) way. I'm presently working on an underperforming string of Sharp 165W...

diysolarforum.com

I looked around the area, and they are the best deal i can find

Covers 900 square feet, and I am paying total $2600

Each panel is about 14 sq feet, and is $40 my cost

each panel is 170 watts

170 watts x 65 panels = 11,050 watts

11000/2600= 4.23 watts per dollar

Is that a good deal?

Look at the pictures, those are the exact panels i will travel to get, do they look good?

 

[Hedges]

Only a decent deal if they deliver near rated power.

$0.25/W isn't bad if panels are good, but such old panels and those in particular I'd want cheaper than most.
I've paid about $0.15 to $0.35 for premium brands REC and SunPower from Santan.
One guy told me he bought recalled panels from sharp for a few pennies per watt.
I would be concerned if they are degraded. Some of mine are still good, putting out 5A Vmp, some were only putting out 1 or 2A. Given that track record I'd rather not pay $0.25/W unless all tested. Which is tedious to do yourself without a panel tester (they are available.)

At least spot check a sample of them. MC3 pigtail cables, couple of space heaters in parallel (switch on 600W & 900W elements as required to get R = Vmp/Imp), turn thermostat up all the way so it doesn't cycle. Cover panel or rotate edgewise toward sun while making/breaking connection if you don't have suitable switch or breaker.

This vintage panel is about 120W/m^2 (before degradation.) Newer panels are 200 W/m^2. Which is why I realized buying new panels I could remove my existing ones and get 50% more power without buying more mounting hardware. Original panels cost me $5/W 20 years ago.

 

[joesmith123]

Only a decent deal if they deliver near rated power.

$0.25/W isn't bad if panels are good, but such old panels and those in particular I'd want cheaper than most.
I've paid about $0.15 to $0.35 for premium brands REC and SunPower from Santan.
One guy told me he bought recalled panels from sharp for a few pennies per watt.
I would be concerned if they are degraded. Some of mine are still good, putting out 5A Vmp, some were only putting out 1 or 2A. Given that track record I'd rather not pay $0.25/W unless all tested. Which is tedious to do yourself without a panel tester (they are available.)

At least spot check a sample of them. MC3 pigtail cables, couple of space heaters in parallel (switch on 600W & 900W elements as required to get R = Vmp/Imp), turn thermostat up all the way so it doesn't cycle. Cover panel or rotate edgewise toward sun while making/breaking connection if you don't have suitable switch or breaker.

This vintage panel is about 120W/m^2 (before degradation.) Newer panels are 200 W/m^2. Which is why I realized buying new panels I could remove my existing ones and get 50% more power without buying more mounting hardware. Original panels cost me $5/W 20 years ago.

Is it possible to test them using volt meter? Would that tell us anything?

 

[joesmith123]

Only a decent deal if they deliver near rated power.

$0.25/W isn't bad if panels are good, but such old panels and those in particular I'd want cheaper than most.
I've paid about $0.15 to $0.35 for premium brands REC and SunPower from Santan.
One guy told me he bought recalled panels from sharp for a few pennies per watt.
I would be concerned if they are degraded. Some of mine are still good, putting out 5A Vmp, some were only putting out 1 or 2A. Given that track record I'd rather not pay $0.25/W unless all tested. Which is tedious to do yourself without a panel tester (they are available.)

At least spot check a sample of them. MC3 pigtail cables, couple of space heaters in parallel (switch on 600W & 900W elements as required to get R = Vmp/Imp), turn thermostat up all the way so it doesn't cycle. Cover panel or rotate edgewise toward sun while making/breaking connection if you don't have suitable switch or breaker.

This vintage panel is about 120W/m^2 (before degradation.) Newer panels are 200 W/m^2. Which is why I realized buying new panels I could remove my existing ones and get 50% more power without buying more mounting hardware. Original panels cost me $5/W 20 years ago.

How about I bring a volt meter, and if the voltage is the same as what it says, then it should be the correct amount of amps?

Do I have that right?

 

[littleharbor2]

You are going to want to get some MC-4 connectors and a crimping tool. Good luck finding any MC-3 extension cable and you don't want to even try crimping MC-3 ends. You will need to cut all MC-3 ends off the panels at the ends of each string and replace with MC-4 ends, then crimping ends onto your home run extension cables.

 

[Hedges]

MC3 is fine.

If you read my thread on measuring PV panel performance, Isc and Voc detected some bad panels, but not others.
Only Imp and Vmp (or I with load and V with load) found those others.

You can take your chances. I'd rather test with a load (I used two electric radiators.)

 

[joesmith123]

MC3 is fine.

If you read my thread on measuring PV panel performance, Isc and Voc detected some bad panels, but not others.
Only Imp and Vmp (or I with load and V with load) found those others.

You can take your chances. I'd rather test with a load (I used two electric radiators.)

Yes I will take a space heater with me

All I have to do is connect the wires coming from the solar panel to the wires on the space heater, and it should turn on?

While the solar panel is in direct sunlight of course

 

[Hedges]

PV DC applied to resistive element is all it takes to get a load, so you can measure V(load) and I(load)

Determine ohms of space heater either by data sheet watts, or better with ohm meter.
Determine by PV panel Vmp/Imp what resistance load would make it operate around MPPT.
See if space heater wattage settings are good for that. My electric radiators are nominally 600/900/1500W, maybe a bit different by measure.

I think I used two heaters, one with 600 + 900 W on, one with 600W on. 2100W at 120V, 2100W/120V = 17.5A, 120V/17.5A = 6.85 ohm

maybe PV panel 35Vmp, 35V / 6.85 ohm = 5.1A
Close enough for my panels.

As described in my thread.

Turn power switches to desired on/off setting first. Turn thermostat up all the way first.
Cover PV panel or tilt away from sun before connecting, then connect.
Expose to sun to take voltage and/or current reading. If you have measured resistance first, you can calculate current from voltage.

You could put MC3 pigtails in the back of an electric outlet. Plug one or two space heaters into outlet.
I did that with switches, one to connect, another to apply short circuit.

 

[EastTexCowboy]

I see that you have those 48 volt eg4 lifepower batteries

Question: Do you have those batteries hooked up in parallel?

Also I see you have 2 mpp lv6548 units

Those are the same as the one I have

And I see you have 32 solar panels

With your setup, are you able to store enough energy to run AC and a fridge overnight?

All batteries parallel. That's the only way 48v batteries will work on a 48v system.

I run 2 central AC heat pumps, a mini split, 5 freezers, 2 refrigerators, and most of the rest of the house including dishwasher, washing machine, microwave, kitchen appliances, 2 computers and a laser printer, and a few other little things. With this heat wave I get down to about 40% SOC by the time I start getting solar again in the morning. I'm cooling around 3000 sf on solar with the only AC on the grid being the upstairs unit. I could probably add it too. They're rock solid.

 

[joesmith123]

All batteries parallel. That's the only way 48v batteries will work on a 48v system.

I run 2 central AC heat pumps, a mini split, 5 freezers, 2 refrigerators, and most of the rest of the house including dishwasher, washing machine, microwave, kitchen appliances, 2 computers and a laser printer, and a few other little things. With this heat wave I get down to about 40% SOC by the time I start getting solar again in the morning. I'm cooling around 3000 sf on solar with the only AC on the grid being the upstairs unit. I could probably add it too. They're rock solid.

omg that is an insane amount of power

What would your electric bill if you were on the grid powering all that?

 

[joesmith123]

PV DC applied to resistive element is all it takes to get a load, so you can measure V(load) and I(load)

Determine ohms of space heater either by data sheet watts, or better with ohm meter.
Determine by PV panel Vmp/Imp what resistance load would make it operate around MPPT.
See if space heater wattage settings are good for that. My electric radiators are nominally 600/900/1500W, maybe a bit different by measure.

I think I used two heaters, one with 600 + 900 W on, one with 600W on. 2100W at 120V, 2100W/120V = 17.5A, 120V/17.5A = 6.85 ohm

maybe PV panel 35Vmp, 35V / 6.85 ohm = 5.1A
Close enough for my panels.

As described in my thread.

Turn power switches to desired on/off setting first. Turn thermostat up all the way first.
Cover PV panel or tilt away from sun before connecting, then connect.
Expose to sun to take voltage and/or current reading. If you have measured resistance first, you can calculate current from voltage.

You could put MC3 pigtails in the back of an electric outlet. Plug one or two space heaters into outlet.
I did that with switches, one to connect, another to apply short circuit.

Watch what this lady is doing

She is detecting current using multimeter

I plan on doing the same

Is her method good enough?

 

[OffGridForGood]

I am tremendously excited for this project

Imagine living on a generator for a year, diagnosing it, coming home to a fridge thats been off for hours, going to get fuel for it at night, babysitting and constant upkeep, changing the oil on it, etc

Imagine if you had all these burdens, and then there might be a way to eliminate all of them

I hear ya, and can relate BUT:
you are too excited and I feel you are about to head down the road at 120 miles an hour, going the wrong way, as you don't know where you are going yet.
My advice - with all due respect and honesty: Don't Buy Anything until the full system is worked out, all components known, and then (only then) get your orders in, and get the equipment, parts, controls etc.
There is a massive brain trust of talent on this forum, we will all help you, but you need to start at the beginning, not the end.
Step one: An audit of the loads you are trying to power - see the Resources section, left had side 'Top Resources' look down the list for System Energy Audit and Sizing
Get to work filling out all you can, and then ask us for some help with anything your not sure about.
I respect your motivated and would like to get this done 'yesterday' but you are doomed to a world of problems going with old panels, that may not suit the system you actually need, that could be crap, I have to advise you this is not the way to a good ending. Trust me.

 

[EastTexCowboy]

I arranged to go get the solar panels from the seller tomorrow late afternoon

I am thinking of ordering those brackets now, just to get them on the way,

But i am still waiting on yalls response to the question:

Will those brackets work for these solar panels?

Yes they will work on just about any solar panel but you need the whole kit, not just the saddle. If you'll email or call them they will help you get the right mounts for your roof including the right number of each kind of kit - outside edge or middle edge (between panels). You need to measure the ridges on your roof to make sure you get the right saddle mounts. Download this brochure for starters -

https://f.hubspotusercontent00.net/hubfs/3482954/Resources/Product%20Documents/Solar/PVKIT%202.0/pvkit-2-0-brochure.pdf

Below is a screenshot. You'll need two of the Edgegrab for each outside panel then two between every two panels that are adjoining. Plus the saddles. I want to say mine came to about $11.00 each. I mounted 32 panels and it was around $900 for 80 complete mounts.

 

[EastTexCowboy]

I hear ya, and can relate BUT:
you are too excited and I feel you are about to head down the road at 120 miles an hour, going the wrong way, as you don't know where you are going yet.
My advice - with all due respect and honesty: Don't Buy Anything until the full system is worked out, all components known, and then (only then) get your orders in, and get the equipment, parts, controls etc.
There is a massive brain trust of talent on this forum, we will all help you, but you need to start at the beginning, not the end.
Step one: An audit of the loads you are trying to power - see the Resources section, left had side 'Top Resources' look down the list for System Energy Audit and Sizing
Get to work filling out all you can, and then ask us for some help with anything your not sure about.
I respect your motivated and would like to get this done 'yesterday' but you are doomed to a world of problems going with old panels, that may not suit the system you actually need, that could be crap, I have to advise you this is not the way to a good ending. Trust me.

This! I agree 100%