Thinking Outside of The Box - Design Help

[harjms]

I've been browsing the forums for the last few months and watching/following multiple YouTubers. We moved into a house with some acreage last fall and have been interested in installing a ground array to help offset some of our energy costs. It first sparked when we got our first true Winter electric bill (~$.22/kwh). It's our first house with a hot tub so we learned quickly that our biggest energy hog during Winter is the hot tub. We use No.2 Heating Fuel with a Boiler for heat/hot water. During the summer, we've found the pool pump and AC units (3 Central Air Systems) are our biggest users for these months.

We've had a few solar installers come by and give us some quotes. All of them were between $40-60K using similar designs. I wanted to use a Sol-Ark 12K as the inverter with some LiFePO4 storage (most included Kilovault). I wanted about 13 kwh worth of panels in any configuration that made sense for the ground array. Unfortunately, this is where the process stopped. I found out the Grid Provider limits the amount of Solar you can install for Grid-tie systems. We are not allowed to install more than 100% of annual usage based on the past 3 years. We had only been in the house for a few months and didn't have any historical usage. The Grid Provider wouldn't provide us the previous homeowner's usage either citing "personal information." Luckily, one of the solar companies managed to pull the historical data and shared it with me. Previous homeowners only used 9,000 kwh a year (avg 3 years). Therefore, the grid-tie system we could install would be lower than what I wanted to install.

With the cost of the quotes, I decided that maybe I could install the system and save some money. I'd be willing to install the lower amount of solar array with the thought process of expanding later on (as suggested by one of the installers). So far, our first year is projected to exceed the previous homeowners usage, but not too much. This is where I started to plan the system. At first, I was going to use Sol-Ark 12K with a Critical Load Panel. I needed a subpanel installed anyways due to no room in main panel. (I've installed said subpanel and moved all critical loads to it). Then the Sol-Ark 15K was announced and would be a great solution as it's a nice AIO and the 200A pass thru was a huge selling point to me. Obviously, the 15K would be oversized, but then I could have larger battery bank for the future.

I started the wire diagram and reading up on the requirements the grid-provider required for grid-tie systems. This is where I'm stuck at how to design the system with either the 12K or 15K unit. The issue I have is the power meter is not installed at the house. It's installed on a pedestal about 120 ft away. Load center is installed in the basement and have no good way to wire in an external disconnect. I have to replace the pedestal (wood rotted) and asked the electrician about installing a main disconnect at the pedestal. He basically said I would have to pull a whole new cable from the meter base to the house (needing 4 conductors vs. 3 that I have now). Also main panel will have to be rewired as a sub panel instead of a main panel (just more labor). I was hoping the main disconnect install would be acceptable by the grid provider as my knife disconnect between the meter and main panel since it's required per their design documents. I'm getting a couple other quotes to replace the wood at the pedestal and will ask the other electricians about the disconnect. If it requires pulling a whole new cable in order to install the disconnect, then I think it'll be a no go for solar.

Details:
200A main panel (bus is 200 amp); so was looking at line-side tap, but may not be acceptable by grid provider - they weren't very clear
Exterior Disconnect Required
Interior Disconnect Required - That will be easy to add in
PV Production Meter - Everyone that I've seen has a production meter on exterior side of house. Documents make it sound like they have a bi directional meter, but new installs (within last week) have PV meter. Not sure if it can be installed in basement as I can not install on side of house.

Inverter was going to be installed in basement next to critical load panel and batteries. Solar Array was going to be installed on North side of the house with array facing South. Conduit was going to be installed between array and inverter (South side of house where load center is).

So my questions are; can you see any other way to install a grid-tie system with some of the NEC 2020 requirements that are imposed without pull whole new cable from meter to house or relocating meter to house (bay windows are installed where underground pipes comes up into basement to main panel).

Has anyone installed solar (recently) with a pedestal installed or meter not attached to structure?

I realize some answers can only be answered by the utility provider, but they won't answer questions from homeowner install without submitting application. Figured I could do some ground work and propose alternative solutions if it meets NEC requirements. I've thought about not attaching into the Grid, but don't think my loads will use all power generated during the summer. Main panel has more demand (hot tub, two AC condensers (2 and 2.5 ton units), but don't think I can afford to run whole home with solar/battery without giving up some of the big loads.

Note: The grid provider does pay $.27/kwh that I produce, so it is a factor to install with grid-tie.

Any help will be greatly appreciated!




(RI Energy Sample for Residential Installs; thus what I'm working with as a sample)


I do have line diagram I drew up, but with the extra items for NEC, I just don't know where to install it.

Thanks in advance!

 

[BentleyJ]

In your detailed post there was no mention of energy conservation. Its easier and more cost effective to save a kW than to produce it, store it in a battery and use it later.
1) Consider the energy savings of replacing the AC condensers with 18 SEER units.
2) Replace the pool pump with Pentair Intelliflow VFD pumps.
3) If the hot tube is being heated with electricity using a resistive element, replace it with a heat pump.
4) LED lights
5) Insulation, windows, air leakage and weather stripping.

 

[harjms]

In your detailed post there was no mention of energy conservation. Its easier and more cost effective to save a kW than to produce it, store it in a battery and use it later.
1) Consider the energy savings of replacing the AC condensers with 18 SEER units.
2) Replace the pool pump with Pentair Intelliflow VFD pumps.
3) If the hot tube is being heated with electricity using a resistive element, replace it with a heat pump.
4) LED lights
5) Insulation, windows, air leakage and weather stripping.

Thanks for your reply. You’re right. I know the best way to save energy is conservation; however, it’s less likely to happen with our normal way of life (first world problems I know). In our last house we had a similar square footage but milder winters. I had a server rack running 24/7, but no hot tub or pool. But we only paid $.07/kWh so it was cheap and we didn’t pay a distribution fee. Our kWh rate here is really like .10 or .11/kWh but with distribution fee it basically doubles the price.

Our last bill was basically $122 in kWh (supply) and $192 for delivery. ?

House was built in ‘06 so not too bad on build. Have energy audit by licensed company done last year and only had a few things recommended (e.g. attic hitch insulated).

5 year goals are to replace AC with heat pumps. Once hot tub dies we won’t be replacing it. Pool pump is only a few years old (previous owner purchase) and will upgrade to VS once it fails. Many folks recommended to keep single speed pump until it dies. I run it for 5 hours a day so not too crazy on usage.

 

[Bkord]

Is there conduit from the meter to the house? Could the wire be pulled out, then add a ground wire and pull the old wire back in. I’ve done this many times, it’s a lot of work. Maybe you could cheat and just bury a ground wire next to the pipe, from the disconnect on the ped all the way to the house. This may not be possible if ther is concrete over the pipe. Is the line to the house copper? Copper is expensive, could a new 4 wire line be pulled in aluminum? Then the old copper be scraped. Sometimes wire can’t be pulled out of pipe that has been in the ground for a long time. What size is the pipe and wire? Could a fish tape or string be ran in the pipe and then just pull a ground in with the other wires. 120’ is far, but maybe worth a try. Did it at my house. But only had to push the fish tape 50’ with the wire in the pipe, was a pain. Took about an hour to add a ground wire in the pipe without pulling any wires out. I did have 2-1/2” pipe. No matter how you do it, it’s going to cost money or a lot of your time.

 

[Danke]

Why the four wires?

I have three L1, L2 and neutral from utility, + house ground. I’m planning on putting in a 200A ATS after meter.

Hope I don’t get some a similar requirement.

 

[harjms]

there conduit from the meter to the house?

I’d like to think so, but the electrician said he’s seen many in our area that only had conduit at the sweeps (meter and house); nothing in between ?.

Line to house is aluminum 4/0. Conduit in panel is 2” so should be 2” all the way through. I really hope there is a pipe all the way.

If push comes to shove, I may be able to get a 4 awg bare copper down the conduit. That may be an option. I need to look at the current wire and see if they just cut the ground line back as it wasn’t needed.

I honestly thought it’d be as easy as installing pulling the 4/0 out of meter base, cutting some conduit, mounting knife disconnect, feed wires that were pulled into disconnect/wire, install new 4/0 piece from otherside of disconnect to power meter. Boom. Done.

 

[harjms]

Why the four wires?

I have three L1, L2 and neutral from utility, + house ground. I’m planning on putting in a 200A ATS after meter.

Hope I don’t get some a similar requirement.

I don’t have the house ground at the pedestal. Ground is at main panel with two ground bars just outside underneath the deck (near the drawn red line in photo).

They made it sound line the neutral ground bond would now have to be at the pedestal vice main panel as it is now in order to install the disconnect switch.

I think you should be good.

 

[Steve_S]

Just to toss another twist into it...
Would it not be possible to wire up the house as follows, 1 AC Panel connected to grid for "Non-Essential" circuits and another AC Panel that is Solar/Battery Only for Essentials and don't bother pushing squat to grid. Personally, I would consider the Air Conditioning, Pool Pump as non-essential where drinking water, fridge, freezer etc are essentials.

I guess you could look at it as what can be run Offgrid and isolate all of that. There are such installations out there.

 

[Bkord]

Why the four wires?

I have three L1, L2 and neutral from utility, + house ground. I’m planning on putting in a 200A ATS after meter.

Hope I don’t get some a similar requirement.

Neural and ground are bonded at the first disconnect. Then after that they need to be separate. He wanted to add a disconnect next to the meter.

 

[harjms]

Would it not be possible to wire up the house as follows, 1 AC Panel connected to grid for "Non-Essential"

That’s the only way I can see installing solar at this point to be honest. I did install a critical loads panel a few weeks ago. On this panel it holds: well pump, fridge (2), freezer, all three air handlers, one ac condenser (1.5 ton), master bedroom and living room lights, network rack and boiler.

My thought was to keep the important items on this for the Sol-Ark 12k but until I get solar installed, it’ll be used for portable generator (using interlock breaker). All air handlers have to be on this as it powers up the thermostats. I’d like to ensure I have heating in case of power outage. Living room lights also power wood insert fan installed.

The trouble I’m having with installing solar for only the critical loads and not back feeding into the grid is the amount I’ll spend for the equipment and getting it set up, will it offset my bill that much to make it worth it? At least if I back feed any excess will help shave my electric bill down. I can’t afford going whole home Solar when I’m using 97 kWh on a summer day in august.

 

[Bkord]

Sol-ark has limit to home mode. So you would not need a net meter agreement. You could get a big battery bank to store power for nighttime.

 

[harjms]

Sol-ark has limit to home mode. So you would not need a net meter agreement. You could get a big battery bank to store power for nighttime.

Will that allow me to connect to main panel (line side taps) to charge up batteries in case of low light or multiple low light days?

Basically I see what you’re saying. Do complete install but without net metering agreement and limit to no export. What happens if batteries are all charged and load in critical load panel is minimum? I know others dump it to a resistive load, but if I don’t have one?

 

[Bkord]

Connect the sol ark to the main panel and critical loads panel. Sol ark will control everything. Don’t need a dump load, it will regulate the pv input. It will slow down your meter but not let it run backwards. Batteries can be charged from pv, grid, generator. Once it’s set up, everything is automatic. Your main panel will pull power from grid, pv, batteries. I ran like this until my net metering was finished. It worked well. I did net metering because I have 12.4kw pv and only 2 eg4 batteries. So I need to put the power somewhere or it gets wasted. If power goes out, your critical panel will run on batteries and pv, or gen it you have that. If I could do it over again I would get the sol ark 15k and more batteries, it was not available when I did my system. The 12k sol ark works great.

 

[LochNess]

Sol-ark has limit to home mode. So you would not need a net meter agreement. You could get a big battery bank to store power for nighttime.

+1. Not doing net metering greatly simplifies your install, mechanically and legally. Plan your big loads when the sun is up and save the excess for night. Most utilities use bi-directional AMI meters nowadays so a second meter is really nothing more than a remote kill switch.