Considering DIY Long distance from panels

[Solarcabin Channel]

IF I would ever see monetary gains by going "off grid"

would I be better off with the inverter near the panels?

You can offset a lot of your grid power with just a small off grid system and in a power emergency you will have some power to keep basic appliances running until the power comes back on. So the benefit is in lower bills and security in the event of a blackout.

I have recommended that for situations where your only sunshine is a long distance from the house. An insulated shed to hold AGM batteries and your electrical components next to the panels and then just run 110v to the house. Less power loss.

It sounds like you have enough roof space for a decent size system but not all roofs are good for solar installation and doing maintenance of a roof system can be a pain. I moved mine to a ground mount system. So you have options.

 

[SeaGal]

...would I be better off with the inverter near the panels? Or, would the DC voltage from the panels be ok traveling this distance and the inverter close to the house/panel/battery pack?

I have recommended that for situations where your only sunshine is a long distance from the house. An insulated shed to hold AGM batteries and your electrical components next to the panels and then just run 110v to the house. Less power loss.

Unbelievable! Another incorrect posting from our new self-claimed solar-emperor.

@Solarcabin Channel PLEASE ONLY ADVISE ON THINGS THAT YOU HAVE ENGINEERING KNOWLEDGE ABOUT

There will be less power loss if you run the high-voltage DC from the panels to the house, rather than invert to 110V and transmit a low voltage.

Basic schoolgirl physics gives you P = I^2 x R. And P=V x I. So, for a given power, higher voltage = lower current = less loss.

That's the reason power companies don't transmit electricity from one side of the country/state to the other at 110V !

 

[georgia088]

You can offset a lot of your grid power with just a small off grid system and in a power emergency you will have some power to keep basic appliances running until the power comes back on. So the benefit is in lower bills and security in the event of a blackout.

What do you consider a "small off grid system"? Would you consider two 48v 100AH lithium packs a small system? The reason I ask about those is I have experience with these packs.

Thanks

 

[Solarcabin Channel]

What do you consider a "small off grid system"? Would you consider two 48v 100AH lithium packs a small system? The reason I ask about those is I have experience with these packs.

Thanks

I lived for many years off grid with just a 400 watt system and three 125Ah AGM batteries.

My system today is just 1.4Kw with a 400Ah LFP on the main system and two recharging stations using a 200Ah LFP and a 200Ah power station.

The average US home needs a 5-7Kw system for basic power so anything under 5Kw and off grid with battery capacity is what I consider a small system.

 

[Solarcabin Channel]

Since the topic concerns voltage drop for AC and DC here is a handy calculator:

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

 

[SeaGal]

The average US home needs a 5-7Kw system for basic power so anything under 5Kw and off grid with battery capacity is what I consider a small system

I know you've ignored me, so I'm wasting my time posting this... but please do us all a favour and stop posting rubbish on here.

For someone who claims to have 20+ years of solar knowledge it seems impossible to me that they:-

a) tell people there is less power loss with low-voltage transmission and

b) don't know their basic engineering units of measurement. K is Kelvin, a unit of temperature. k=kilo. And AFAIAA, our noble Scottish inventor wrote his name as James Watt, not james watt.

 

[Solarcabin Channel]

Something I learned to do by hand in High School, if not Junior High.

The bigger question is, how much voltage drop can you tolerate?
For 120VAC, I'd say about 6V.
For 380Vmp DC, I'd say I could even live with 190V drop (assuming wide MPPT range), I'd be OK with 95V drop, I wouldn't be terribly upset with 38V drop.

Also see if 1000V max is a possibility. Many panels support it and some inverters do.

The only question is, what costs more, silicon or copper (aluminum if you like.) You can offset the loss, within limits, by putting up more panels. That can make sense with 500' or 1000' distance.


For OP, 1000' for 4 awg aluminum is 0.5 ohms.
If he uses 4 strings of 10 amp panels, 40A will produce 20V drop.
An 80 Vmp system would drop to low for charging 48V battery but would work for 24V battery.
A 200Vmp system would work fine, lose 10% only during times of highest production (which usually doesn't matter if not grid-tied.)
A 400 Vmp system would only lose 5%, close to the guidelines others recommend.

Depends on what voltage you need to that controller and wire gauge you want to use.

If you run 48 volt and 12Awg 500 feet you will lose:

Voltage drop: 2.01
Voltage drop percentage: 4.19%
Voltage at the end: 45.99

Compared to AC 120 volt and 12Awg:

Voltage drop: 1.75
Voltage drop percentage: 1.45%
Voltage at the end: 118.25

500 feet is a long run so HVDC might be a better choice but more expensive install and my recommendation was in general for smaller installs.

 

[Solarcabin Channel]

I know you've ignored me, so I'm wasting my time posting this... but please do us all a favour and stop posting rubbish on here.

For someone who claims to have 20+ years of solar knowledge it seems impossible to me that they:-

a) tell people there is less power loss with low-voltage transmission and

b) don't know their basic engineering units of measurement. K is Kelvin, a unit of temperature. k=kilo. And AFAIAA, our noble Scottish inventor wrote his name as James Watt, not james watt.

See calculator here: https://www.calculator.net/voltage-drop-calculator.html

And results here:

If you run 48 volt and 12Awg 500 feet you will lose:

Voltage drop: 2.01
Voltage drop percentage: 4.19%
Voltage at the end: 45.99

Compared to AC 120 volt and 12Awg:

Voltage drop: 1.75
Voltage drop percentage: 1.45%
Voltage at the end: 118.25

500 feet is a long run so HVDC might be a better choice but more expensive install and my recommendation was in general for smaller installs.

Your personal attacks and continual trolling is why you are being ignored.

 

[WindWizard]

It seems to make a lot of sense to put a large solar array in the open field and then use the 4/0 aluminum wire as the carrier for the PV.

Putting the equipment in a shed in the field sounds like a lot of future trouble in the works.

I like to keep all the Charge Controllers and other equipment in the house where you can monitor them.

I am also a big fan of off grid sense you are not in the power companies back pocket plus you can do your own work without all of the permits required for grid tie. The LFP Cells are reasonable and putting together a DIY pack is fun and saves money.

 

[Lt.Dan]

See calculator here: https://www.calculator.net/voltage-drop-calculator.html

And results here:

If you run 48 volt and 12Awg 500 feet you will lose:

Voltage drop: 2.01
Voltage drop percentage: 4.19%
Voltage at the end: 45.99

Compared to AC 120 volt and 12Awg:

Voltage drop: 1.75
Voltage drop percentage: 1.45%
Voltage at the end: 118.25

500 feet is a long run so HVDC might be a better choice but more expensive install and my recommendation was in general for smaller installs.

Your personal attacks and continual trolling is why you are being ignored.

Who the hell would run 48vDC that far?

You are also not including what current you are using In your calculator.

 

[WindWizard]

If you run 48 volt and 12Awg 500 feet you will lose:

Voltage drop: 2.01
Voltage drop percentage: 4.19%
Voltage at the end: 45.99

Compared to AC 120 volt and 12Awg:

Voltage drop: 1.75
Voltage drop percentage: 1.45%
Voltage at the end: 118.25

The Solar array can be like 400 Volts DC. Using the 4/0 aluminum wire then the voltage loss will be a whole lot less. Why would anyone want to put the Charge controllers in the field and run 48 Volts?

 

[SeaGal]

Your personal attacks and continual trolling is why you are being ignored.

I beg to differ. I have only made corrections where it is apparent that the information you have posted is wrong or dangerous. And objected to your arrogance.

No one would even think about transmitting 48V over 500 feet for a system designed to go off grid with a usage of 40 to 50 kWh per day.

With all due respect, please go back to your shed and you-tube and leave the basic electrical engineering to those that know about such things.

 

[Solarcabin Channel]

Who the hell would run 48vDC that far?

You are also not including what current you are using In your calculator.

Use the calculator and set it for any distance and wire gauge you want.

The data is to compare apples to apples.

 

[Solarcabin Channel]

The Solar array can be like 400 Volts DC. Using the 4/0 aluminum wire then the voltage loss will be a whole lot less. Why would anyone want to put the Charge controllers in the field and run 48 Volts?

Use the calculator and set it for any distance and wire gauge you want.

The data is to compare apples to apples.

 

[Solarcabin Channel]

Thanks for the voltage calculator. It seems to work great. I ran it with more realistic numbers.

400 Volts DC 30 Amps 500 feet 4/0 Aluminum wire

Voltage loss 3.29 Volts.

What did you get with AC 120 volt and same wire gauge?

If I plugged the numbers in correctly:

Voltage drop: 0.11
Voltage drop percentage: 0.096%
Voltage at the end: 119.89

 

[SeaGal]

I just grabbed some data off the net of a 450 watt panel. 8 of these would give me about 278V when in series? Which would mean I would need to find a inverter that could handle 500vish? What else would I need to look for in an inverter? What about specs for a Charge Controller? Again, this is IF I used 2 48v 100AH lithium packs.

I'll let others comment on that as there are different models available over there, than in the UK where I am. I get the impression that Deye / Sun-Synk / SolArk have a good following in the USA. I have a Solis in the UK. BTW have sent you a PM too.

 

[Solarcabin Channel]

True for a small system, and AGM is simple, just have temperature compensated charging.
Couple of PV panels, and run 120V back to the house. Should work fine up to 12A at 120V, which would cause 6V drop (5%)

OP said 50 kWh/day so I'd figure 10kW PV (if that consumption was summer not winter.)
My original 10kW system was four strings of PV panels, about 7.5A each at 380 Vmp so 30A on the home run wire.

Some where in between, might have 150V or 250V PV string to an AIO.

I am a small system off grid guy so that is what I focus on and try to help people with those systems to understand what we are talking about in these posts so it relates to them.

Your experience with large and grid tied systems is much more than mine I am sure.

 

[SeaGal]

What did you get with AC 120 volt and same wire gauge?

If I plugged the numbers in correctly:

Voltage drop: 0.11
Voltage drop percentage: 0.096%
Voltage at the end: 119.89

Sorry, but it is impossible to be less voltage drop for same power at a lower voltage, because the current will be greater, R is the same and V=IR.

Those figures look inherently wrong to me - what current was used to come up with that?

 

[Solarcabin Channel]

have only made corrections

please go back to your shed

Your personal attacks like the one above and continual trolling is why you are being ignored.

Hopefully the moderator has taken notice.

End of discussion and putting you back on ignore.

ADDED: By the way my "shed" as you referred to it has been featured in Mother Earth News, Treehugger, and in Lloyd Kahns book and was built for cash. No house payments, no utility bills and freedom!

 

[CoolWill]

I know you've ignored me, so I'm wasting my time posting this... but please do us all a favour and stop posting rubbish on here.

For someone who claims to have 20+ years of solar knowledge it seems impossible to me that they:-

a) tell people there is less power loss with low-voltage transmission and

b) don't know their basic engineering units of measurement. K is Kelvin, a unit of temperature. k=kilo. And AFAIAA, our noble Scottish inventor wrote his name as James Watt, not james watt.

You forgot to mention that the convention is to put a space between the number and units too: 5 kW.