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And people say solar is expensive....

I just finished installing my 7.2KW solar system , SMA inverter, rapid shut down, Iron ridge racking and JA 315w panels, all permits and fees and parts. $7300.....$3400 after tax incentives from state and fed. Of course my labor was free:).
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nwdiver

Well-Known Member
Feb 17, 2013
9,181
13,929
United States
NIce !
That looks almost exactly like the projects the volunteer group I am part of puts up.

One detail though: that exhaust pipe is going to wreck havoc with your generation, particularly in a serial setup. Are you able to monitor output ?

Do you mean parallel? Shading one section of a panel in series should only cut out 1/3 of the panel. However if two strings are in parallel lowering voltage on one string throws off production on the other string forcing it to operate off its MPPT. The great thing about the new SMA inverters is each string can be on its own tracker so shading losses are minimized.
 

SageBrush

REJECT Fascism
May 7, 2015
14,121
19,550
New Mexico
Do you mean parallel? Shading one section of a panel in series should only cut out 1/3 of the panel. However if two strings are in parallel lowering voltage on one string throws off production on the other string forcing it to operate off its MPPT. The great thing about the new SMA inverters is each string can be on its own tracker so shading losses are minimized.
I meant serial, and I was presuming that this array is all in one series.

You know a LOT more about diode shade protection than I do, so I'll keep quiet and hope OP can provide detailed generation detail.

Tangentially, I sure would like to see building regulations that require pipes be placed on the non-solar facing roof face.
 
Last edited:
NIce !
That looks almost exactly like the projects the volunteer group I am part of puts up.

One detail though: that exhaust pipe is going to wreck havoc with your generation, particularly in a serial setup. Are you able to monitor output ?
I know the system is not optimal, but the house is not big and has a hip roof. I used all the available space on the southern roof i could. You kind of have to work with what you have. I hopefully oversized it some to compensate for shading. there are 2 strings that have separate MPPT tracking in the SMA inverter. All I can do is hope for the best. The roof faces about 195-200 Deg. south/west. If worst comes to worst I can add another small string on the south/east side later. I will post some figures after the meter is set by the power company. Sometimes it can take weeks:(. I am waiting for the city inspector as I type this.
 

nwdiver

Well-Known Member
Feb 17, 2013
9,181
13,929
United States
I know the system is not optimal, but the house is not big and has a hip roof. I used all the available space on the southern roof i could. You kind of have to work with what you have. I hopefully oversized it some to compensate for shading. there are 2 strings that have separate MPPT tracking in the SMA inverter.

You should be fine; That's what I really love about the new SMA inverters; the latest version has up to 3 MPPTs. IMO having each string on its own tracker is really all you need as long as every panel on a string is facing the same direction. I've got an old-school single MPPT inverter. If 1/3 of 1 of 42 panels gets shade I can easily lose ~5% since the voltage of the other 2 strings must drop also. If each string has its own tracker you're really only losing the shaded section. String-level optimization is just as effective as module-level at a fraction of the cost.

Have you tested your Secure Power Supply without ANY AC power? We had to rethink how we implement SPS on our inverters due to rapid shutdown. Rapid shutdown needs AC to turn the panels on and with SPS you need DC from the panels to get AC... still trying to figure out the best way around that. Rapid Shutdown with SMA appears to be somewhat of an after thought especially the module level shutdown that's required next year. They essentially outsourced it to TIGO.
 

SageBrush

REJECT Fascism
May 7, 2015
14,121
19,550
New Mexico
You kind of have to work with what you have.
Listen to NWDiver and not me, but monitor generation if you can. If the shade cast by the pipe is a big deal you can always remove a panel or two, or place them somewhere else on a separate string.

Your other alternative, if the shade only reaches your bottom row, is to isolate the top row on separate string.
 
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I just finished installing my 7.2KW solar system , SMA inverter, rapid shut down, Iron ridge racking and JA 315w panels, all permits and fees and parts. $7300.....$3400 after tax incentives from state and fed. Of course my labor was free

That is very impressive, for such a system at just 1000 /kw , whereas the least quote for install I got was $2.35/W.
If I may ask. Could you post where you could source the necessary panels, inverters and other components and prices.
That would help wannabes like me to go for solar install diy.
 

mspohr

Well-Known Member
Jul 27, 2014
12,078
16,154
California
I recently expanded my system with some SunPower salvage panels that I got a good deal on (free). They are monsters. 420 watts and 70 volts. Running 6 of them on a single string to a SMA inverter.
Total cost (mostly the inverter) about$1500 for 2500 watts and of course DIY. I'm getting about 15 kwh/day. I figure less than 2 years payback.
Solar is cheap.
 
You should be fine; That's what I really love about the new SMA inverters; the latest version has up to 3 MPPTs. IMO having each string on its own tracker is really all you need as long as every panel on a string is facing the same direction. I've got an old-school single MPPT inverter. If 1/3 of 1 of 42 panels gets shade I can easily lose ~5% since the voltage of the other 2 strings must drop also. If each string has its own tracker you're really only losing the shaded section. String-level optimization is just as effective as module-level at a fraction of the cost.

Have you tested your Secure Power Supply without ANY AC power? We had to rethink how we implement SPS on our inverters due to rapid shutdown. Rapid shutdown needs AC to turn the panels on and with SPS you need DC from the panels to get AC... still trying to figure out the best way around that. Rapid Shutdown with SMA appears to be somewhat of an after thought especially the module level shutdown that's required next year. They essentially outsourced it to TIGO.

Yes ,I did turn off the breaker and tested the SPS. I hooked a 400w light to it for a minute to check it ,but that is all.
 

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