sun exposure at my house

ghcoupons · July 2014

Hello, new guy here, somewhat new to solar and I'm trying to learn. My main question is about the sun hours I'll get at my house. I have seen some sort of a dial that shows the winter and summer sun and where the trees will hit, etc, but I'm not sure where to get one, if they're very expensive or even what they're called.

Thanks for the help!

ghcoupons · July 2014

Re: sun exposure at my house

Well no sooner had I posted this than I came across some apple apps that provide a 3D augmented reality type scenario. I'm not sure what I'm looking at. It shows the path of the sun and various markers so I assume this is used to show the pathway of the sun and what objects are in the way, but I'm not sure how to hold them or use it. lol

westbranch · July 2014

Re: sun exposure at my house

Depending on the resolution of the satellite imagery of your area, ours is low and 5 years old, you can use a tool in GoogleEarth...

ghcoupons · July 2014

Re: sun exposure at my house

does it have a name in google earth? I'd like to look that up. ive only seen a screen shot of the tool im looking for, but it showed a fish eye view of the sky overhead, the path of the sun in winter and summer and then any obstacles you may or may not encounter. I want to see what my home is like from a solar panel perspective. I suspect I'll need to trim some trees. Thanks for the reply.

zoneblue · July 2014

Re: sun exposure at my house

The are three significant factors involved;

1. weather adjusted insolation in your area, see pvwatts. This is the most important one.
2. obstructions from the natural landscape. For most people these will be insignificant, but some solar modelling software can build whats called a 3d DEM model to show the horizon for your house. Like i said, its unlikely this will be important, even if you live next to a 10000ft mountain, because the obstructions are near the horizon when insolation is at its lowest point in the day.
3. loca shading, neighbours houses, trees, etc. Unless you live in one of special google urban areas this data wont exist anywhere but out of your two eyes. You can buy products that will show these, but only professional installers generally (can afford) to use them. Observation is your best tool there.

Does that answer your qu?

ghcoupons · July 2014

Re: sun exposure at my house

zoneblue wrote: »

The are three significant factors involved;

1. weather adjusted insolation in your area, see pvwatts. This is the most important one.
2. obstructions from the natural landscape. For most people these will be insignificant, but some solar modelling software can build whats called a 3d DEM model to show the horizon for your house. Like i said, its unlikely this will be important, even if you live next to a 10000ft mountain, because the obstructions are near the horizon when insolation is at its lowest point in the day.
3. loca shading, neighbours houses, trees, etc. Unless you live in one of special google urban areas this data wont exist anywhere but out of your two eyes. You can buy products that will show these, but only professional installers generally (can afford) to use them. Observation is your best tool there.

Does that answer your qu?

Well, yes and no...sort of. lol Sorry for the basic questions here. I live in a hilly wooded area so I fully expect to encounter some tree blockage. If one tree was cut down I think solar could work very well in the summer at least. I looked my place up on google earth but it was a very fuzzy pic that was old and didn't provide much data. Using observation as you suggested makes me think the long southern facing portion of my roof and the shorter east facing portion of my roof could be a candidate. I do not recall how much sun we get in this area of the roof in winter due to trees on the hill above us, but then again the leaves will be gone so I expect this is a common obstacle. All that was one of the reasons I wanted to find a tool that would show both seasons and the suns path. Would it help if I posted pics of my roof facing due east (from a compass) to give you an idea of what I'm dealing with?

I found an app I may use but I was unsure about mentioning it as it may appear I am spaming, which I assure you I am not. Here is a screen shot of what I'm talking about and I removed the name. Thank you again for the assistance.

ghcoupons · July 2014

Re: sun exposure at my house

also, I did find a pvwatt calculator online and entered my info. What numbers should I focus on or post up here?

Thank you.

PNjunction · July 2014

Re: sun exposure at my house

Our own forum host provides some very good practical 2D charts you can use if you are in the U.S. :

http://www.solar-electric.com/solar-insolation-maps.html/

Most of us design around winter, for example in Los Angeles, that would be about 3-4 hours at best. This would be used for the calculations to ensure that your battery can get a decent charge, depending on how deeply discharged your battery is, and the size of the array.

Of course this doesn't take into account extremely local conditions like nearby shade trees. However it will get you into the ballpark fast and you can design a system around the charts.

ghcoupons · July 2014

Re: sun exposure at my house

PNjunction wrote: »

Our own forum host provides some very good practical 2D charts you can use if you are in the U.S. :

http://www.solar-electric.com/solar-insolation-maps.html/

Most of us design around winter, for example in Los Angeles, that would be about 3-4 hours at best. This would be used for the calculations to ensure that your battery can get a decent charge, depending on how deeply discharged your battery is, and the size of the array.

Of course this doesn't take into account extremely local conditions like nearby shade trees. However it will get you into the ballpark fast and you can design a system around the charts.

These are very helpful posts, thank you for everyones help. I see where I am at and have other questions for a different thread. Thank you.

zoneblue · July 2014

Re: sun exposure at my house

ghcoupons wrote: »

also, I did find a pvwatt calculator online and entered my info. What numbers should I focus on or post up here?

PVwatts is easy to use. Put your array azimith and elevation in, and it wil give you a table of equiv sun hours for each month of the year. This is weather adjusted, and uses satelite irradience models, they claim an resolution of around 10km.

You take the 12 monthly figures, the highest might say 5hrs, the lowest 2hours. How big of a difference between winter and summer, plus your budget, and access to other charging sources, will determine your design target. Money notwithstanding youd aim to cover the winter figure. If you have a genset you can forget the three lowest months. If you have hydro, you can worry less about those months. Etc.

If you have tall trees close to your place, then youll either have to cut them down, or move the array to a clearing. Solar and shade arent really happy bedfellows. If you can get solar access from mid morning to mid afteroon, then your good to go. Dont sweat the margins.

sun exposure at my house

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