10kW Ground Mounted Solar Panel System

[Pettrix]

I am looking to do a 10kW ground mounted adjustable solar panel system. I am on 15 acres so I have plenty of room for ground panels. I also will want them to be adjustable so I can change them from winter to summer sun angles.

I currently use under 600 kWh of electricity per month. That will go up slightly as it will be servicing another energy efficient house.

I am tied to the grid and will remain that way. I am still on the fence about doing a lithium battery backup system. Costs and possible fire risk with those systems has me apprehensive.

The solar panels will be coming from China (over 80% of the panels are made there). Not sure which type/brand of inverter I want to go with.

Any ideas/input would be appreciated. Anyone else here with ground mounted panels? Did you use concrete form tubes to use as anchoring points for the solar panel rack system?

 

[ericm979]

If you don't have net metering, you may also want batteries to time-shift power consumption from your panels. For example the new rules in California pay close to zero for power you send to the grid so the only way that solar pays off is if you also install batteries so you can keep your excess power to use at night.

Supposedly the newer batteries that use Lithium Iron Phosphate are safer than the batteries used in laptops and cars.

If your area has multi day outages in the winter consider a system with a way to use a generator to top off the batteries. Some of those like Enphase require a serious standby generator, some will let you use a portable gas generator.

 

[ning]

Carefully calculate any extra costs that the adjustable mount(s) may incur over the cost of a basic fixed rack, vs the expected increase in electricity - particularly if the solar is to augment grid power.

This is slightly different, but when I was putting my system in, there was a choice in which microinverters to use; one had a higher capacity which would not "clip" the peak output, but cost a bit more - over the expected life of the entire array the extra cost was unlikely to be paid for by the slight amount clipped by the lower capacity units.

> possible fire risk with those systems

No appreciable fire risk with LiFePO4 batteries and they're a better bet in the long run regardless.
If you can afford ~30-40kWh or more of battery, I doubt you'll regret the purchase; batteries also allow you to make more efficient use of a back-up generator (it can run at higher load = max efficiency when the batteries are low for recharging them, then turn off and let the house run on battery, until it needs recharging again, etc).

 

[ultrarunner]

I have a 6kW 3 array hillside mount with panels now 15 years old.

Twice a year I adjust the angle and it's about a 5 minute job for all 3 arrays.

The mounts were expensive and required additional city inspection for the depth of hole and rebar...

My panels are 160W and now they would be double or more in the same footprint

 

[ning]

I'm likely to add 5kW to my system in the next few years, and I'm more and more interested in an adjustable mount, so please let us know what your research is finding - even if it's a mount system you've decided not to use. The data and reasons for your decision could be very helpful for me everyone here now and in the future.

 

[davrow]

I definitely recommend any DIY solar folks watch a lot of Will Prowse videos on YouTube. Very informative.
Will Prowse DIY solar

 

[fatjay]

I have a 6kW 3 array hillside mount with panels now 15 years old.

Twice a year I adjust the angle and it's about a 5 minute job for all 3 arrays.

The mounts were expensive and required additional city inspection for the depth of hole and rebar...

My panels are 160W and now they would be double or more in the same footprintView attachment 1870533

What size are the 160w panels? I would bet money that you are virtually the same watt per square foot as modern panels. Density hasn't increased by a measurable amount. 320w panels are literally double the size of 160w panels.

 

[sd455dan]

I'm likely to add 5kW to my system in the next few years, and I'm more and more interested in an adjustable mount, so please let us know what your research is finding - even if it's a mount system you've decided not to use. The data and reasons for your decision could be very helpful for me everyone here now and in the future.

LD1 turned me onto Sinclair sky-rack 2.0. It is all US made steel, galvanized and 50 KSI. They have options for heavier duty posts and racking depending on wind, snow load, and panel weight. They have screw jacks at each post so the angle can be set wherever it needs to be and they will custom punch the direct mount rails as well which saves money as well. The shipping was the only thing that was a bit pricey - about half of the rack cost but happy with the quality.

Eventually may add more panels and may experiment with a mount like ultrarunners with tracking

Here is LD1's solar is complete thread.

Solar is complete

Finally got everything done with solar....so time to dump some pics. Site prep was challenging.... hillside.... The racking is Sinclair sky-rack 2.0 seasonal adjust. They spec'd a 7' deep hole 24" in diameter. Had to make an auger extension for that. Panels are Canadian solar 540w bifacial...

www.tractorbynet.com

 

[ultrarunner]

What size are the 160w panels? I would bet money that you are virtually the same watt per square foot as modern panels. Density hasn't increased by a measurable amount. 320w panels are literally double the size of 160w panels.

I would need to measure and post as it was a long time ago…

 

[MAX-24-Dean]

Desert southwest, This area has the maximum sun hours per day of anywhere in the USA. I wouldn't be to concerned about the need to adjust your array tilt there, because of this.
Lived in AZ with solar and I just used a non-adjustable ground mount, because it was the cheapest way to go.
My solar arrays in Washington State are also non-adjustable ground mounts, not much gain in the winter months here when adjusting tilt.
A 6 panel array in a 65 mph wind could easily have in the range of 1800 lbs of uplift forces. I use an 18" auger on a skid steer for all my installs and drill to 54", and install per the manufacturers written instructions for the spacing of the holes. Prop up the upright sch 40 and pour a 3,000 lb air entrained fiber mix. No rebar in the holes, this meets any engineered specs I have seen.
Just prop the verticals up off the bottom of the hole so they do not have soil contact.

Plugged in a 10 kilowatt system for Casa Grande, AZ. Based on high desert in the southwest.
The attached pdf; output is based on 10 kwatts of panels and is from the pvwatts site at the link here. It is quite accurate. You can play around with the tilt angle for your location to see the difference you would achieve, but I think you will find that it won't make to much difference at your latitude.

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations

pvwatts.nrel.gov