Grid-tied solar

[farmer2009]

I agree....micro inverters are the way to go now. Very simple, as close to "plug and play" as you can get. My system is a mixed bag....6kw on grid tie w/battery backup, and another 5kw on micro inverters (Enphase). Just finished up a 10kw system for a neighbor. 40-250w Hyundai (86cents/watt) and 40-M215 Enphase inverters. Built the racking out of 2" pipe with 2x2x3/16" galvanized angle for the panels to sit on.

Could you give us a cost break down for someone wanting to install themselves and also build their own frame vs buying everything.

 

[Barry 1]

Is the rack all bolted together? How about some close up shots?How did you attach angle to pipe?

 

[TnAndy]

Everything is welded. Best closeup I have:

Here is a slightly better shot of my fixed mount rack. I used 1 1/2" pipe, because not near as high off the ground (my south face slopes back UP a hill, where the neighbor's slopes downward from his south face), and only went 2 panels in portrait mode.

What I do is cut a short piece of the same angle, weld it on the pipe, then lay long angle on top that with a face up to bolt to the panels.

My previous arrays are on home built trackers, as you can see on the pole to the right side of the photo. The photo is from late afternoon and the array is now tilted west.

I would NOT recommend anyone do that now that panels prices are a buck/watt and under....just put up more panels and be done with it.

 

[TnAndy]

Could you give us a cost break down for someone wanting to install themselves and also build their own frame vs buying everything.

Panels, as I said, run 75 cents to a buck/watt. Good website with ever updating prices, who sells them for what, and how many you have to buy to get the price listed is:

Solar Panel Price Survey | EcoBusinessLinks

Then add shipping to your location. Most places in the lower 48, you're talking 300-500bucks for a pallet load.

Enphase inverters run in the 125buck/range.....I've seen them under 120....you just have to search. Every time I buy solar equipment, seems like a different dealer has a better price....so I don't have any recommendations as to WHO to buy from. Shop.

You also have to buy the cable to go with the micro inverters....runs about 20-25bucks per "drop" (connection for one inverter), and a couple little accessory pieces.

Racking on the 10kw system ?

We used 14pcs of 2" galvanized pipe @ $75ea
We used 15pcs of 2x2x3/16" galvanized angle @ $42ea

About 1700 bucks

The bracing inside was some scrap stuff he got at a junkyard, don't know what it ran.

6 yards of concrete went in around the trenches we set the pipe bases in.

Welding rods, cans of spray paint, etc....I didn't really keep up....he was getting the stuff...

My guess is he had around $2500 in the whole rack, not including what I, and another neighbor, charged for labor.

 

[Carl_NH]

Hi Andy,

Nice installation - and appears to be cost effective too. So hardware for this 10KW is $17K range then installation - what is the rough total with installation and wiring estimated?

How far is the array from the power source typically? Does that impact the output at all if you need to run a hundred feet or more of cables to the power panel?

 

[buickanddeere]

Our local utility told us that the local 2.2MW substation does not have the capacity for a 5KW net metering connection. They have no problems however with our 25KW of electric heat.

 

[TnAndy]

Hi Andy,

Nice installation - and appears to be cost effective too. So hardware for this 10KW is $17K range then installation - what is the rough total with installation and wiring estimated?

Carl,

He had a total of $23,106 (he had to give total to the power company, and I had to sign off with my NABCEP certification) in it, paying me, another guy, and an additional guy a day or so (pouring concrete, pulling wire, etc). He had his own mini-excavator, which helped a lot. He bought the wire/conduit, etc, so I really don't know what all he had in that. Guy is a doctor.....good surgeon, great writer of checks and general all around Go-Fer......ahahahaaa

How far is the array from the power source typically? Does that impact the output at all if you need to run a hundred feet or more of cables to the power panel?

Most installs are roof mount....it just wouldn't work in this case, house just didn't sit right, and the guy has 40 acres, so out someplace else wasn't an issue. Since most are roof mount, the distance usually isn't much of an issue.

With central inverters, the panels are run in long strings (like 10-15 panels) and that gangs up the voltage, keeping the amperage the same. (fairly low). Most central inverters operate in the 300-500vDC input range, and most won't even "fire up" (produce) until they get enough sun on the panels to hit 200+ volts (DC). So most are run with fairly small wire...#10 or #12....unless we're talking really long distance.

The micro inverters change the panel low voltage DC (usually in the 30-35vDC range) to 240vAC right there at the panel (those shiny square looking boxes are the inverters).....so, again, you have a fairly high AC voltage to deal with, but amperage becomes more of an issue. Each of the micro inverters puts out about 1 amp, but in parallel......so when you run 40 of them (in this install), you get about 40amps max. Enphase limits you to 17 inverters (using the M215 model used here), and a 20amp branch circuit.

What we did was install a weathertite panel at the racking, backfeed 3 circuits (two '13' panels/inverters, and one '14') into 3-20a breakers, then used a 60a main to feed down the hill ( about 120' ) to the separate meter that backfeeds into the system (here, they require a separate meter for solar production, most places don't). We ran two #4 wires THHN in conduit (+#10 ground), which is heavier than required, but he does plan on some expansion down the road, so we built in for that.

Voltage drop is more of an issue with long runs AND low voltage.....especially DC voltage. On grid tie systems without battery backup, it's not a huge deal. Throw in batteries, and it's gets trickier. You have a charge controller the panels have to feed first in line, and it needs to be located in an enclosed area & close to the battery bank....so you have to bring DC to it, and most charge controllers limit the infeed to 120 or so volts DC (depends on the max cold your area is subject to....the lower the temp, the more the panel voltage rises)....so you're limited to strings of 2-3-4 panels using 250w panels.....like I said, battery systems tend to get a WHOLE lot more complicated real quick.

Too much information ?

I tend to do that.......

 

[tkappeler]

Subscribed. Lots of great information. Am considering a DIY on our 4 acres. Thanks and keep the info coming.

 

[farmer2009]

Carl, He had a total of $23,106 (he had to give total to the power company, and I had to sign off with my NABCEP certification) in it, paying me, another guy, and an additional guy a day or so (pouring concrete, pulling wire, etc). He had his own mini-excavator, which helped a lot. He bought the wire/conduit, etc, so I really don't know what all he had in that. Guy is a doctor.....good surgeon, great writer of checks and general all around Go-Fer......ahahahaaa Most installs are roof mount....it just wouldn't work in this case, house just didn't sit right, and the guy has 40 acres, so out someplace else wasn't an issue. Since most are roof mount, the distance usually isn't much of an issue. With central inverters, the panels are run in long strings (like 10-15 panels) and that gangs up the voltage, keeping the amperage the same. (fairly low). Most central inverters operate in the 300-500vDC input range, and most won't even "fire up" (produce) until they get enough sun on the panels to hit 200+ volts (DC). So most are run with fairly small wire...#10 or #12....unless we're talking really long distance. The micro inverters change the panel low voltage DC (usually in the 30-35vDC range) to 240vAC right there at the panel (those shiny square looking boxes are the inverters).....so, again, you have a fairly high AC voltage to deal with, but amperage becomes more of an issue. Each of the micro inverters puts out about 1 amp, but in parallel......so when you run 40 of them (in this install), you get about 40amps max. Enphase limits you to 17 inverters (using the M215 model used here), and a 20amp branch circuit. What we did was install a weathertite panel at the racking, backfeed 3 circuits (two '13' panels/inverters, and one '14') into 3-20a breakers, then used a 60a main to feed down the hill ( about 120' ) to the separate meter that backfeeds into the system (here, they require a separate meter for solar production, most places don't). We ran two #4 wires THHN in conduit (+#10 ground), which is heavier than required, but he does plan on some expansion down the road, so we built in for that. Voltage drop is more of an issue with long runs AND low voltage.....especially DC voltage. On grid tie systems without battery backup, it's not a huge deal. Throw in batteries, and it's gets trickier. You have a charge controller the panels have to feed first in line, and it needs to be located in an enclosed area & close to the battery bank....so you have to bring DC to it, and most charge controllers limit the infeed to 120 or so volts DC (depends on the max cold your area is subject to....the lower the temp, the more the panel voltage rises)....so you're limited to strings of 2-3-4 panels using 250w panels.....like I said, battery systems tend to get a WHOLE lot more complicated real quick. Too much information ? I tend to do that.......

So you are licensed to install solar. Is it required or what you do? Are you also an electrician?

 

[TnAndy]

So you are licensed to install solar. Is it required or what you do? Are you also an electrician?

I have a certification from the national solar bunch, which is required for grid tie connection here (but not all places). I've held a State of TN electrical license in the past, but let it go (due to expense of renewal) when I retired. Homeowner here can pull their own permits, and that is what I had this guy do.