Overcoming distance?

[Helpme]

Hello to everyone. As you might have already guessed by me screen name, I may be a little needy. At any rate, here goes my question.

I am in the planning phase of our new pv system. Our meter is on a pole about 200’ from the north side of our home. The pole is very close to the nearest place to ground mount our pv array. I, probably like many of the newbie solar rangers, have put the cart before the horse and ordered my solar panels before I got far enough into my research/education, and now I’m at the point where I need to start figuring out what electronic devices (charge controller, inverter/charger, etc) I should use and what type of system I am building.

I had figured to do a 4x4 system of strings in parallel which based on my 40.73(VOC) and 10.79(ISC) would result in 162.92(VOC) and 43.16(ISC) at my combiner box. Of course you can see my problem here, having 53.95(ISC) , based on the additional 1.25 added for safety. This setup could work with some serious wire. I believe it is 2|Oawg based on Sunking’s chart.

So now, do I just build a shed and go hybrid grid tied to the pole(which also gives multiple options) or do I just pay the wire guy for the 2|0 cable, or do I use micro inverters?

I would really like to do a 48v system and my initial thought was to do a hybrid hybrid grid tied system wherein to use the grid as a backup power supply, but I do not actually net meter back to them.Thank you for reading. Any advice will be appreciated.

[Mike90250]

Micros will not likely work with that long of a cable

You look beyond the 150V charge controllers.
Schneider, Morning Star and Midnight all make charge controller with high voltage PV inputs up to 600VDC

https://www.morningstarcorp.com/prod...tar-mppt-600v/
https://solar.schneider-electric.com...-controller-2/
http://www.midnitesolar.com/pdfs/hawkes_bay.jpg ( in final weeks of design/LIRP )

So you could wire your panels in series, 2 strings of 8, for 350Voc and just 20A (use a breaker/combiner box at the array with the proper sized breaker)
and get by with much smaller wire. Double that size and you can use aluminum wire and save a lot of money. Make sure your breakers are rated for aluminum connection
( say your calculation for copper is 4 awg. Simply use 2awg aluminum wire and the proper anti-ox lube at the connections. easier to pull too )
and you would use copper for the rest of the connections.

[foo1bar]

Our meter is on a pole about 200’ from the north side of our home. The pole is very close to the nearest place to ground mount our pv array.

Do you really want/need to have a system with batteries?
Or are you better off doing a grid tie system and having a generator (or two) for when there are power outages?

If you're doing a hybrid system, I do not think you can use microinverters - at least the microinverters I know (enphase) are just grid-tie

If you are doing hybrid, then I think you need to figure out what the charge controller / inverter you'll be using is - and the batteries. And figure out the shed to hold them that you'll have by the pole. Probably the inverter/charge controller you choose will have multiple inputs and be able to take higher voltage, lower current from the panels and feed the batteries at the 48V (or whatever) that they need. Assuming you have 300W panels, (and 16 of them), you'd have a max power of about 4800W. 4800W / 48V = 100A. 100A is significant. So you'll need some very thick wire (or good sized copper bars acting as your conductors) from the charge controller to the big batteries that you'll need. Fortunately the distances involved for that should be pretty short - I would expect you'd have the batteries and the charge controller/inverter to be within a few feet of each other.
For the wires from the panels to the charge controller - probably I'd look if I could do two strings of 8 panels - 8 * 40 == 320V (probably reasonable for a lot of charge controllers.) And if it has dual-inputs, it's 10.79A on each wire from the charge controller to the panels. 10.79A means you don't need very large wire (probably the main thing you'ld increase the size for is to reduce resistance losses.)

If you're looking to do solar to save money, most likely you're not going to save money by doing anything that's using batteries.
I think it's still a good idea to evaluate the financials of doing a hybrid system.
But I think grid tie with generator is likely to be much better for the financial side of things.

[Helpme]

Thank you Mike! I originally didn’t have the micros in mind and between you and foo1bar, I believe that options is out. I had wanted to get all my batteries and electronics in my basement. The other option is the shed near the pole. I did look at those larger inverters, but for some reason I am stuck on Victron and really would like to do a complete system with their products. Being new to this and not an electrician by any stretch of the imagination, I am always open to suggestions.

If I can build the shed with a basement for cooling and heating batteries, maybe I can just tie into the grid there at the pole and use the existing lines to get power into the house? If I do the 4x4 setup with those numbers I can use a victron 250/100 with a Quattro 10,000?

Running the bigger cable is between $1500 and $2000 based on what I’ve been able to find so far, so I’d save at least that much and I’m sure I can build a shed with a basement for less than that?

As far as the generator, I have a 14kv with auto cycling I plan to use in my system and I am building a pair of 48v 280ah batteries, which should provide about 28kWh for around $2000/ea.

Stil struggling to learn as I go. Thank you both so much for your responses and your time.

Soon solar at any price will be a bargain. Have a blessed day

[Mike90250]

Sorry I missed the Pole, was a PoCo grid pole. I have my arrays on pole mounts, and thought you were dithering between pole mount and ground mount.

If you have grid power, batteries are a colossal waste of $, unless you are building a UPS to run things for 5 min till the generator starts up.

When you add batteries, you must consider the "reserved regions" of charge you should not dip into, 50% of your avaib ah for lead acid, or 60% avaib for LiPo4
Since you are taking about cooling and heating batteries - that sounds like LiPo4 cells. You need a robust BMS that integrates with your charge controller, or a big gasoline powered fan to blow the toxic fumes away when the batteries burn up. Your choice....
https://www.renewableenergyworld.com...fire-disaster/

[chrisski]

Since you are taking about cooling and heating batteries - that sounds like LiPo4 cells. You need a robust BMS that integrates with your charge controller, or a big gasoline powered fan to blow the toxic fumes away when the batteries burn up. Your choice....
https://www.renewableenergyworld.com...fire-disaster/

Thanks for the story. I think I’m starting to see the dangers of lithium ion batteries. Also in the same town I live in,

[Helpme]

Hello Mike!

The BMS I am using is the Daly 48v 16s 500a, I will use 16 of the eve 3.2v 280ah cells available on alibaba or Ali express. They are rated around 14kWh. Not sure if I mentioned in my initial post, but my meter is on the pole near (20’) where my array will be. I think I have settled on the Outback sky box and plan to go grid tied as foo1bar had suggested. I mean what else will I do with the extra energy I create?

As stated my array is 16 panels x 350 or 5600, which is a little more than the skybox needs. I’m thinking to drop to 14 panels (2 strings of 7) and see how this performs.

my consumption is around 27kWh per day, so even at peak this system will under perform my needs, but if I can just cut out my peak hour usage @$6.50kWh I stand to save $50 per month. My contact at the PoCo tells me net metering rarely affects those peak hours, so then I must program my skybox to use the batteries during these times. That current consumption is around 8kWh per month and the is also 15kWh of “off peak demand that they hit me for $1.50kWh. If I can stop these two leaks in my bank account.

My initial system with (1) skybox (1)48v 280ah battery and 1 14 panel 4900w array will cost me around $9500 +\- and is a 13 year pay off. My plan also includes doubling this system to two of each of everything in my list, which hopefully will reduce my 824kWh per month bill to $0 and will reduce my payoff time to 10 years.

The only item I have not included in my build cost is my system shed, which I am still planning. I heat with an outdoor furnace. As a tree guy I get the wood for practically free. So that may be my heat source for the shed or I might place my system in my shop, which is relatively close to the pole. <75’ and is also heated by the wood furnace.

Thank you all again! I am listening and your advice has been helpful. Any further advice will be surely appreciated.

[Ampster]

Those 280 Ahr cells appear to be the same LiFePO4 (LFP) cells i have been using for the past six months with an Outback Skybox. They are not matched so it is important to parallel top balance them. The cells will arrive at about 50% SOC and it may take some time to do that. Will Prowse has some videos that may be helpful to thoroughly understand that process.

The Skybox was designed from the ground up to be grid interactive and there are various modes you can choose to optimize the benefits of a grid connection. The voltage range of the built in MPPT controller is 250-600 volts and that may give you more flexibility on locating the panels with less concern about the kind of losses incurred at lower voltages using typical charge controllers. The Outback user forum may be helpful to understand how different users have configured their Skyboxes.
The Chinese BMSs like Daly typically overstate their capacity so you are wise to pick one with a larger capacity. The DC circuit breaker on the Skybox is rated at 125 Amps so you will have a good margin with that BMS. Your panels would most likely not be able to provide enough energy to charge at more than 100 Amps from solar. I have 42 kWh of those batteries and only charge at 60 Amps.

You will will also want to install a critical loads panel to optimize the capability of the Skybox with the grid connection.. Tell us more about the location of your main service panel and how the loads to your house are fed and you may have some choices about where to locate the batteries.

[Ampster]

A quick calculation on the VOC you listed would bring the string voltage to 560 volts with 14 panels and depending on temperatures in your area that might be safe margin below the 600 volt max string voltage of the Skybox. There was a recent discussion with tech support about that issue on the Outback user forum.

You will have more flexibility about locating your inverter and batteries with a higher string voltage than the assumptions in your initial post. The Skybox has a 60 Amp breaker on the Generator input so your current 14kW inverter should work well.

As far as future expansion is concerned you have several options based on your needs. Economics will depend on the terms of any Net Energy Metering arrangement you may have with your Power Company. I can discuss in more detail depending on your needs. Your consumption and location will drive whether that will mean more panels for solar generation. Micro inverters, AC coupled to the Skybox can be a cost effective way to incrementally add generating capacity once you have maxed out the Skybox inverter.

[Helpme]

Hello Ampster! I checked out the diy solar forum and the outback forum. If I decide to go with the Skybox and I use two of them will that give me 10kw up and down and the ability to add a second 14 panel string? Also, what bms did you use on you eve cels. Which sources did you use. I’d like to go ahead and get my second order of 16s on the way. I’m sorry honking 28kW will be a good starting point?

Thanks again to all of you fellas. Great to have your input

[Weldman]

Here to wake this thread up as I am curious, what if you want to go over 600 VOC to overcome long distance and not put in multiple charge controllers, is there a charge controller that can take it beyond to 1kV or higher?

[Helpme]

I ended up going with the Sol-Ark 12k and they recommend using only 10AWG for runs up to 300’ at 500VOC

[SunEagle]

Here to wake this thread up as I am curious, what if you want to go over 600 VOC to overcome long distance and not put in multiple charge controllers, is there a charge controller that can take it beyond to 1kV or higher?

Most standard wire is only rated for 600V. Going to 1000V could be an issue unless you get special high voltage wire. So finding a CC that can handle that voltage may be a very special case.

[Ampster]

......... what if you want to go over 600 VOC to overcome long distance and not put in multiple charge controllers, is there a charge controller that can take it beyond to 1kV or higher?

The 2017 NEC increased the limit for ground mounted arrays from 1000 volts to 1500 volts so there are panels and presumably string GT inverters that can now take those voltages. As far as charge controllers that can charge a pack which has a nominal voltage of 48 volts that may be a different animal. One poster here increased his wire size in aluminum to overcome voltage loss. In his case he was already using string inverters. At some point wire size versus more expensive charge controllers have to have tradeoffs.

[Weldman]

Seems from my math wire is cheaper than CC's if one has to buy two or more which is why I was looking around for possible answer of if there was one out there rated higher than 600V.