Grid Tie Solar Installation

[jhurkot]

In this thread I'll be covering the install and performance of a grid tied solar installation at our farm house. I'm a journeyman electrician and will be doing this install myself as much as possible (minus concrete work). My goal is to show the total cost of the system, time and labour to install, and set up/performance. The first step is figuring out what we use for power in a typical year. I've been using a neurio to monitor the energy usage since 2017 so here are some charts....

 

[jhurkot]

 

[doorfx]

Excellent ! A REAL electrician.

 

[jhurkot]

So this is my plan right now.
1. Assess how much energy we are using annually.
2. Figure out what size and type of system as well as an estimate for annual solar production
3. Obtain estimate for total cost of system
4. Figure out how long the system will take to pay for itself

Now if step 4 does not make economic sense that will be as far as it goes. Since we are displacing gasoline with 3 EV I'm sure this won't be an issue, but I won't rule it out.

5. Contact Fortis with system details and get permission to begin the project
6. Doing the actual work
7. Inspection and approval to be connected to the grid (as well as 2way meter installation).

I've never done anything like this before so it will be a bit of a learning experience for me. Took a "solar for Journeyman electricians" course at SAIT in 2017 but I don't even remember what I did yesterday so I'll have to brush up on that and the code changes since as well.

 

[Ridgeclough Ron]

Why is your consumption higher some months such as may in 2019. And why is july 2017 high. Is this a farm operation or a farm house. It would seem power consumption would be highest dec, Jan, feb, when the days are shorter and vehicles are plugged in. July is a higher month for me if I have the Ac working.

 

[Ridgeclough Ron]

Not trying to discredit you, just trying to see if this is a direct comparison to my house. I am very interested in your project and could possibly help you with the cost of the concrete.

 

[Annacassandra]

I work for an electrical utility (not fortis) so here are some other things to consider in your cost vs benefit analysis.

When selling power back to the grid you only get paid for the energy produced but when buying from the grid you pay distribution and transmission charges as well- these can be much higher cost on your bill than the price of energy (depends or your service territory and utility provider). Most solar energy is produced at times when your actual consumption is low so the amount of energy you produce typically would have to be much higher than the energy you consume in order to have a significant impact on your bill.

Also, the efficiency of solar panels drops substantially in the winter time due to the angle of the sun being lower and fewer daylight hours- so in winter you could be producing 20-40% of what you can produce in the summer. Since these are usually peak consumption months for most people it again impact the benefits you're likely to see on your monthly bill.

Not to steer you away from your plan but those are jusr some other things to consider.

 

[jhurkot]

Why is your consumption higher some months such as may in 2019. And why is july 2017 high. Is this a farm operation or a farm house. It would seem power consumption would be highest dec, Jan, feb, when the days are shorter and vehicles are plugged in. July is a higher month for me if I have the Ac working.

This service is just the house. We had a Chevy volt (13kwh) the whole time. Added the model S (100kwh) in Sept 2017 and model 3 (75 kWH) in dec 2018. Not sure why some months are abnormal in consumption, depends a lot on how much driving is being done.

 

[jhurkot]

I work for an electrical utility (not fortis) so here are some other things to consider in your cost vs benefit analysis.

When selling power back to the grid you only get paid for the energy produced but when buying from the grid you pay distribution and transmission charges as well- these can be much higher cost on your bill than the price of energy (depends or your service territory and utility provider). Most solar energy is produced at times when your actual consumption is low so the amount of energy you produce typically would have to be much higher than the energy you consume in order to have a significant impact on your bill.

Also, the efficiency of solar panels drops substantially in the winter time due to the angle of the sun being lower and fewer daylight hours- so in winter you could be producing 20-40% of what you can produce in the summer. Since these are usually peak consumption months for most people it again impact the benefits you're likely to see on your monthly bill.

Not to steer you away from your plan but those are jusr some other things to consider.

Absolutely, these are some things I really considered. All 3 cars will be home during the day usually so the goal will be to use the 200 kWh of battery to deal with excess energy. Here is the estimate for generation on a 17KW DC system for our area....



I valued a kWh at $0.10 which is higher then put back into the grid but far lower than purchased from the grid.
Also looks like the system will cover the annual usage of kWh.

 

[Cdnfireman]

Am I understanding that correctly that You’re gonna be using the batteries in the vehicles to back up the system? And that you’re estimating that you’ll be getting 10 cents/ kWh that you’ll sell back to the grid?

 

[lilduke]

I think his goal is to charge the 3 cars and he values that power @ .10c KW/h


At least thats how I read it.

 

[ABMax24]

Here's a few things I learned on my setup:

Contact your utility first once you decide to pull the trigger. ATCO was by far our biggest holdup. All other permits and approvals were in place before they sent over the micro-gen contract (we had a written informal approval before this). The system was also installed for almost 2 weeks before they managed to install the 2-way meter.

Check requirements with your municipality on if engineering of the support structure is required. We needed an engineer to sign off that our existing roof trusses were strong enough to support the panels. This may also apply to ground mounts.

Check into energy retailers, some have better rates for solar generators. I use Spot Power, our rate goes to 18.5c/kwh in the summer and increases our earnings while generating more than we use, we switch back to 6.5c/kwh for the winter months.

Also if you like numbers and cool graphs you can download a program called System Advisor Model from the NRL. They also created that PVWatts calculator you posted about.


I'm not sure if you are putting in a fixed array or not, but it might make sense to install a single axis array that you can manually change seasonally for maximum output.

Also do you plan on going with string inverters or micro-inverters? And mono or poly panels?

 

[jhurkot]

Am I understanding that correctly that You’re gonna be using the batteries in the vehicles to back up the system? And that you’re estimating that you’ll be getting 10 cents/ kWh that you’ll sell back to the grid?

Oops, that wasn't really clear. Vehicles are not going to power the house, they will simply be a place to store excess production. I would far rather have what we are generating to go into a battery than be sold to the grid for 8cents only to be withdrawn later at 20 cents. As far as the price I chose to value a kWh at I decided 10 cents is fair because if we are producing our annual usage with solar we should be getting the majority of our power from the array. Not to say we won't be using the grid, because we definitely will but it should be reduced a lot. Night time power consumption should be pretty low. Neurio says 600watts always on or 12cents/hour.

So right now we will use the grid as a battery but will have to input 2.4 kWh to withdraw 1 kWh (when it's not being consumed by the house or cars).

 

[jhurkot]

Here's a few things I learned on my setup:

Contact your utility first once you decide to pull the trigger. ATCO was by far our biggest holdup. All other permits and approvals were in place before they sent over the micro-gen contract (we had a written informal approval before this). The system was also installed for almost 2 weeks before they managed to install the 2-way meter.

Check requirements with your municipality on if engineering of the support structure is required. We needed an engineer to sign off that our existing roof trusses were strong enough to support the panels. This may also apply to ground mounts.

Check into energy retailers, some have better rates for solar generators. I use Spot Power, our rate goes to 18.5c/kwh in the summer and increases our earnings while generating more than we use, we switch back to 6.5c/kwh for the winter months.

Also if you like numbers and cool graphs you can download a program called System Advisor Model from the NRL. They also created that PVWatts calculator you posted about.


I'm not sure if you are putting in a fixed array or not, but it might make sense to install a single axis array that you can manually change seasonally for maximum output.

Also do you plan on going with string inverters or micro-inverters? And mono or poly panels?

These are great points, thanks! Will be ground mount on concrete and for the concrete specs I'm just going to get that info from the manufacturer.

As far as the rates that's another thing I need to look into as that would help a lot but I can always play with that stuff after the system is installed.

Current system design is going to be a fronius 15kw string inverter with 48 370watt modules (72cell). Total cost for 17.7kw system is $1.31/watt (includes inverter, wiring, modules, racking) does not include some cable (inverter to power pole) or concrete work.

For what it's worth I priced out a 12.2kw system last year and it was the same price although that system used different modules and micro inverters.

 

[doorfx]

Why not micro inverters?

 

[jhurkot]

Why not micro inverters?

Microinverters have their place when you have shading issues or on a roof mount with a non-uniform configuration. For a bigger sized ground mount with a clear view of the sky a string inverter is going to be more cost efficient imo. I might ask the wholesaler what the price difference is just for curiosity sake.

 

[doorfx]

If you lose a micro inverter your whole array doesn’t go down. They have also really come down in price. I believe wiring will be cheaper as well.

 

[08arcticcat]

Have you considered taking that 25g that youd spend on solar and putting it into a high dividend account and using the returns to offset your electrical bill?

25000 x 4.4%(XEI etf) = 1100/year

Maybe its better to get solar if your not planning on moving and leaving the solar system behind.

I built a 40000btu/hr glycol heater this year to heat my shop. It works well but will take a long time to recover costs. It is a cool project though

 

[jhurkot]

If you lose a micro inverter your whole array doesn’t go down. They have also really come down in price. I believe wiring will be cheaper as well.

That's true with the string inverter I have a single point of failure potential. Fronius is a very reputable brand with good warranty though so it shouldn't be an issue. With microinverters the wiring is more expensive because you have to use their trunk cable. Also need to use a gateway to communicate (700$). If you have a smaller system and want to monitor the performance of every individual module it's definitely better. It's also better to use micro inverter if you want to build half a system now and half later. More adaptable, more failure resistant, maybe better production? My #1 goal for the system is for max production per dollar spent. But I will get back to you on the price difference if I were to use micros for this exact system because I think that's an important number to know.

 

[jhurkot]

Have you considered taking that 25g that youd spend on solar and putting it into a high dividend account and using the returns to offset your electrical bill?

25000 x 4.4%(XEI etf) = 1100/year

Maybe its better to get solar if your not planning on moving and leaving the solar system behind.

I built a 40000btu/hr glycol heater this year to heat my shop. It works well but will take a long time to recover costs. It is a cool project though

I wish I put $25k into TSLA at $180/share....
Even if you are planning on moving I think it's still worth it. Should add 3-4% value to the house. Also very interested in the aspect of using the energy of the sun to fuel my transportation.
Also $1100 would only allow the purchase of 5500kWh of electricity per year (1/4 of our consumption).
That heater set up sounds interesting, post pics.