Residential Solar

Maybe this was already brought up. Anyone thinking about this, contact your electricity provider. It shouldn’t cost anything for them to come out and look things over. In our service territory about half of solar installs 10kw and bigger require an upgrade to the service, in some form. Most solar companies don’t mention this and it can be several thousand dollars more. If there is a house fire this will be one of the first things looked at. A phone call for a little CYA is easy.



Owl

 

Holy cow, that is a huge hit for extra inverters. I assume my quoted price would be lower if I didn't have an inverter for each panel. But my situation warrants separate since I have shade. I would think you wouldn't need such an arrangement - I'm assuming since you are looking at ground mount that you would not have shade concerns.

 

I have been watching the area where I thought would be a good spot for the panels and lo and behold, shade is a factor on a huge scale! Micro inverters do have their advantages when it comes to dealing with this as you know.

 

spotted owl I did contact my elec provider just to see if they had any incentives for solar. There was no mentions of upgrading the system. I don't know what could possibly be required to upgrade unless the homeowner had the old 60 amp (or even the 100amp) elec service to the house. Then, most definitely, I could understand the required upgrading.

 

Our local power company (community owned) not only offers no incentives for solar (or much of anything) they are pretty much solar adverse...if you want to install it, fine, but you are not putting any of it back in the grid. So it makes no sense to put in any more than what you can use yourself...and to make it even less attractive, we have pretty low electric prices anyways...so ROI is gonna be pretty long

 

My contract specifically mentions the following, "Client shall be responsible for all costs associated with transformer upgrade or any other upgrades deemed necessary by the utility".

My electric panel is 100 amps and I don't have to upgrade that. Of course I have no idea what would be required if I wanted a larger system. The original proposal was for 12k kwh production (14.8 array output) - there was a slight misunderstanding of what I was asking for. Who knows what upgrades that would have entailed, if any. That would have been 37 panels and would have required more stringent permitting from the utility. And would have been about the price that yooperdave second bid came in at (before tax incentives).

However, that would also have thrown it into a high enough bracket that I would be paying my town extra taxes (they waive taxes for up to $30k of the worth). IDK, in a couple of days the price per kwh is going up to $0.24 it might have paid off huge down the road. But, I wasn't ready to spend that kind of dough to support all my neighbor's electrical addiction during grid overload (I'm being tongue in cheek here, so don't bash me please).

 

I did the math. If I did solar, 3 months of electricity savings each year would go toward paying additional property taxes. I believe, at the time I looked into it, the value placed on each panel was $420 regardless of output. My town obviously doesn’t subscribe to the state approved tax abatement program..

 

I'll have to go over my proposal once again to see if there is any mention of transformer upgrades necessary. Wouldn't that be the power company's responsibility anyway?

 

I've been playing with the calculations for a solar system. Some houses will need a panel or service disconnect upgrade if a line side tap is not utilized.

The sum of the grid and solar inverter breakers cannot equal more than 120% of the busbar rating.

My garage has a main breaker box with a 100 amp main breaker on a 125 amp rated busbar. 125 x 1.2=150amp total so I could have a PV panel breaker up to 50 amps with my 100 amp main. 50a x 240 V is 12,000W. But since the PV breaker is considered a continuous load it should be sized 125% the inverter power rating. That means the largest PV array I could have is 9600W.

My 200amp house panel has a 200amp bus bar. The works out to a max 40amp inverter and max inverter size of 7680W. My larger 200 amp breaker panel allows a smaller PV array due to the busbar rating.

Most 200 amp breaker boxes would have to be upsized to 300 or 400 amps to get n PV array/inverter bigger than 7680W. It's typically cheaper to do a line side tap below the meter and add a dedicated AC fuses disconnect for the PV array/inverter.


I'm looking at a 6000W system on a 30amp breaker connected to my 125amp rated busbar in my garage breaker box with a 100amp main breaker. I will do as much install as possible. PV panels, mounting hardware for ground based install, disconnect, and inverter shipped are quoted to be $9000. I still need conduit and wire to connect the array to the breaker box.

Per PVwatts website, I can expect an average $60 savings per month. That's about a 10 year simple pay off. My electricity is below $0.10/kW....now

 

The power company would do the work, but it is not "necessary" work to keep the grid up, so they would charge for it. That was part of the approvals process the solar company goes thru. They don't know what the power company may or may not require, so that would be an extra.

Was any of that in English - LOL.

 

I'm glad I wasn't the only one who found that to be clear as mud!

Meche_03 I'm sure it is simple as heck and you have a firm grasp on the understanding of it, but I'm not at that point yet!

Sounds like a great way to save some $$

 

Its alright Meche_03 makes sense to me

 

Coffee hasn't kicked in yet............

 

I understood you Meche_03 but gramps was an electrician.

 

Gotcha now. Where would you find out the busbar amperage rating?

At any rate, now I know where the extra costs would/could accumulate.

 

Yeah. The card games we played this morning reflected my need of that process too. I had my butt handed to me!

This is ready to go now.

 

Oh my.....

 

The busbar amperage rating, along with many other specs like lug tightening torque will be listed on the inside surface of the breaker panel door/cover.

My house breaker panel doesn't list a busbar amperage so I have to default to the amperage of the main breaker. The garage breaker panel is much newer and lists the busbar amperage.

One may be able to Google the panel make and model number to find archived specifications not listed.

 

Thanks.