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Re: This is how I do solar

Posted: Fri May 10, 2019 7:34 pm
by Oilpan4
Got my roof mounts in.

The only big thing is to get the insufficient lam beam made from three 2x8 boards. It can't even hold up my buildings roof with out sagging. Definitely not going to hold another 700 pounds of solar panels out of my building and replace it with a 24 foot I beam that I got at the scrap yard.
My mechanical engineer says my steel I beam should be at least as strong as a lam beam using four 2x12s.
A special order 24 foot long 2x12 costs around $100 each. This old steel I beam was $37.
A new steel beam would cost at least $600.

The electrician needs to pull permits for my tie in and install. Guess he will do it when he needs money.

2019-05-10 20.34.01.jpg

Re: This is how I do solar

Posted: Sun May 12, 2019 11:48 am
by Oilpan4
I weighed the unistrut, panels, conduit and a roll of wire that I will probably use up.
Probably be pushing 900 pounds.

Re: This is how I do solar

Posted: Mon May 20, 2019 1:26 pm
by Oilpan4
I will probably get a sunny boy sma 5kw.
Get a used one for $600, that makes the 3.6kw portion cost $432.

The sunny boy has 3 inputs so I could do 3 to 3.6 south facing like I was planning then also add on an array of 1 to 2 kw of South east facing panels plus 1 to 2 kw of South west facing.
If I get this inverter I will be looking to have it make close to 5kw from sun up to sun down.

Run the numbers again.
The constants are panel cost, the cost of the mounts and racks for up to 3.6kw of roof top panels, the budget for the inverter. So all I have to do is ground mount more panels.
I will likely make up to a 6kw system on a 5kw inverter.
So let's say $2,500 for 3.3 to 3.6kw of roof top I was planning to do.
Then let's say I add a south west array of 2.4kw, up to 3kw.
(The sunny boy sma likes at least 250vdc on its inputs, 2.4kw puts me at 280 vmp. 2.1kw or 7 panels might work but that puts my vmp at the low end of the recommend vmp.

So the additional 2.4kw to 3kw of panels should only need about $300 to $380 worth of racking and attaching for ground mount (no expensive rack feet).

To add up to 3kw of SW facing ground mounts should run about $1,150. Just panels, unistrut, anchors, wire, no inverter.

I will probably start with the minimum. 3kw of roof top panels and 2.1kw of SW facing panels and just see what happens, then add panels from there.

$3,650 for up to 6.6kw of panels on a 5kw inverter.
Only problem is I really down know what the pay back on the south west facing array will be. I could assume it would be producing around 70% of the south facing arrays production.

Re: This is how I do solar

Posted: Thu Jun 13, 2019 4:44 pm
by Oilpan4
Got the sunny boy sma 5000 TL
For 2 reasons. It was cheaper and it has the secure power supply.
The TL only has 2 inputs but this should match up very well with my 295 watt panels.
The secure power supply feature acts like a stand alone inverter and allows you to use up to 16 amps of 120v 60Hz power when the power goes out and with the sun high in the sky, as long as your panels can support it.
That way you aren't staring at your thousands of dollars worth of solar power generation equipment wishing it worked at least a little when the power goes out.

Cost, $455 shipped to my door or about 9 cents a watt.
My budget was up to $600 for a non SPS sunny boy so double bonus for waiting.

Rolling budget is:
26 cents (actual price paid) to 30 cents a watt for panels (depending on how over paneled I run the inverter).
25 cents a watt for roof top racking, wiring, conduit.
9 to 11 cents a watt for inverter (depending on how much I over panel the inverter)
5 cents a watt for the tie in and permits ect.
My budget was 70 cents a watt.

I can probably do fixed ground mounts for closer to 15 cents a watt.
If I do some ground mounts later on I will be well under 60 cents a watt on that portion of the system.