effect of house E/W orientation on solar generation

[gamb00ler]

I currently live in a rental while we design/build a new home in CM.  The rental has a large area covered with a corrugated metal roof in the front yard.  It has an unobstructed Southwest exposure.  I think the slope is about 15-20°. I realize the SW orientation is going to either reduce the efficiency of the panels or require a complicated mounting system to yield the maximum production.  I also plan on moving the installation to the new home which will have a SSW (approx 16° from East-West) facing roof.  I will seal the mounting holes in the rental roof to leave things as when I moved in.

 

If I just mount the panels to match the roof orientation I'm guessing the peak production time would be shifted to later in the day and overall efficiency would be reduced by some factor.  I don't want to go for the optimal mounting because it will only be used for 8-10 months.

 

How do I calculate the reduction factor?  Or is there a web site that would do that for me?  Any other recommendations?

 

We're retired and this rental doesn't offer the facilities for other hobby choices.  This will hopefully be a cheap way (in the long run) to keep me occupied.

 

Rental unit still has the old style leccy meter.  Anyone know if the installation at our new house is likely to have the old style meter after conversion from temporary hookup?

 

 

Edited February 7, 2021 by gamb00ler

[gamb00ler]

For the mathematically inclined, there is https://www.pveducation.org/pvcdrom/properties-of-sunlight/arbitrary-orientation-and-tilt to answer my question about reduction in solar cell inefficiency caused by less than optimal angle to the sunlight.  However that only calculates the instantaneous effects and will not tell me the reduction over any period of time.

 

It's an interesting web site with a lot of theoretical details about solar power.

Edited February 8, 2021 by gamb00ler

[BritManToo]

Don't even think of doing this until you are in your own home and on your own standard meter.

The PEA won't approve a DIY install.

The PEA won't approve a moved approved install, you have to buy from scratch again.

An approved installation using approved equipment takes over 8-12 months, and it costs a fortune.

[gamb00ler]

2 hours ago, BritManToo said:

Don't even think of doing this until you are in your own home and on your own standard meter.

The PEA won't approve a DIY install.

The PEA won't approve a moved approved install, you have to buy from scratch again.

An approved installation using approved equipment takes over 8-12 months, and it costs a fortune.

I thought it was quite common for those exploring solar potential not to involve PEA.

 

I'm pretty sure our current meter is a standard old style meter.

 

Edited February 8, 2021 by gamb00ler

[Crossy]

38 minutes ago, gamb00ler said:

I thought it was quite common for those exploring solar potential not to involve PEA.

I'm pretty sure our current meter is a standard old style meter.

 

It is, although PEA do seem to be getting more enthusiastic about stopping people net-metering (spinning the meter backwards).

 

The old disc-type meters will usually run backwards (occasionally they have a no-reverse mechanism) the new electronic meters do not run backwards unless programmed that way.

 

PEA are definitely starting to install electronic meters around Pattaya, not sure about anywhere else yet. You're probably only going to find out when you get your permanent supply.

 

3 hours ago, gamb00ler said:

It's an interesting web site with a lot of theoretical details about solar power.

 

The practice rarely follows the theory, but it never hurts to check what theory says. 

[Danderman123]

The rule of thumb is the slope of the panels should equal your latitude. 

 

I suspect that any southern orientation should be good enough as long as the slope angle is appropriate. However, most people use the most power in late afternoon, so facing a bit west would be useful. 

Edited February 9, 2021 by Danderman123

[gamb00ler]

2 hours ago, Danderman123 said:

The rule of thumb is the slope of the panels should equal your latitude. 

 

I suspect that any southern orientation should be good enough as long as the slope angle is appropriate. However, most people use the most power in late afternoon, so facing a bit west would be useful. 

The roof's slope is close in value to CM's latitude so I wasn't much concerned about that.

 

After some consideration of the overall impact of the rental and new home's orientation, I came to the same conclusion that higher productivity in the later afternoon hours would actually be a benefit.  We generally don't run the A/C much before 2PM.  I would be happiest if our consumption peak is aligned as much as possible with our production peak.

[Muhendis]

Since we are about 15 degrees north of the equator it follows that for part of the year the midday sun will be shinning from the north and later from the south. To improve efficiency you could consider having several tilt settings which can be manually set (every four months for example) as the year progresses.  I do like the idea of orientating the panels for maximum production during maximum consumption although having batteries to charge that is not something I would personally consider. Battery charging takes priority and needs to be done sooner rather than later in the day.