Well.... the initial assessment from the utility company is a no go based on the transformer that feeds my home and my neighbor's. I am checking to see the max allowable size and also what it would cost to have them upgrade it.
A bit disappointing, but what can one do. Updates to follow as I receive them.
I looked at the same thing when I did mine. One mechanical issue with the Sunmodo was that the length of the uprights only allows up to 35deg, if you want to go higher you'd need longer uprights. Not sure they have them available. The other option is to lower the front edge right down to the ground, but we get a lot of snow so didn't want to do that. I found a few engineering papers that showed stress difference between 35 and 45deg, it was really large. As I recall it was about 5 times larger for some of the bending stresses. So you need to either use larger pipes, or add the appropriate diagonal bracing.The next step here, and I have a couple questions for you all, is to solidify the array size for the fronius 15k units (3) and also get engineered plans for the ground mount system at 45* instead of the original 30-35. I'll be calling victor engineering, who does the plans for sunmodo, to talk with them to see what it would cost to get the sunmodo engineered for 45* and stamped plans. Once I have that then I can submit for permitting with the county. Once that is done (electrical permit should be easy) then I am ready to start buying components!!!
Is there a better ground mount system out there that would be configurable to 45* without additional engineering?
Fronius data sheet for 15kW model shows recommended input range of 12-18kW, don't see a problem. On the best days so far I've gotten 83% of the rated output of my panels. We haven't had any cold weather yet so that might go up slightly, but I'd be surprised if you ever see more than 85-90% of the rated output in the real world.Here is a concern of mine regarding the array size. I am looking at the Hyundai bifacial panels (450W without the bifacial effect). 450 * 16 * 2 = 14,700W per fronius unit. If I said they could produce an additional 25% at peak production then that would equate to exactly 18kw, which is the absolute max that the fronius units are spec'd for on the PV side.
One, panels may only produce max wattage on the frontside for a few hours a day at best. Two when they are producing max then the sun should have much less of an effect on the back side due to the nature of where the sun is positioned to get that max production. I'm thinking that there is not anything to worry about in regards to providing too much power to the fronius units. Any thoughts on this????
That's a bargain.I spoke with the utility company this week and they have the estimate to upgrade the transformer here. It is currently a 25kVA transformer and they will charge me $1700 to upgrade to a 50kVA unit. They said they will approve my system once that is upgraded. They have no problems with the size or design.
It won't be an issue. The recommended PV input wattage range for the 15kW Primo is 12kW to 18kW but that doesn't mean you can't have more than that. Indeed it would likely cope with 20kW provided the MPPT voltage limits were not exceeded.Here is a concern of mine regarding the array size. I am looking at the Hyundai bifacial panels (450W without the bifacial effect). 450 * 16 * 2 = 14,700W per fronius unit. If I said they could produce an additional 25% at peak production then that would equate to exactly 18kw, which is the absolute max that the fronius units are spec'd for on the PV side.
Front edge and average snow are both 36", but it's next to the barn in kind of a wind tunnel so we get a lot of drifting. Crossing my fingers I don't have to go in there with the tractor and clear snow.