Announcement

Collapse
No announcement yet.

Is south the best direction for your panels?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • stekicar
    replied
    My roof points NW-SE. I have 30 panels on NW side and 8 on SE side. Each panel is 330W. At 50% DOD, my batteries are full by noon during summer and by 2PM during winter on sunny days. My battery capacity is 250ah 100% usable (total of 500ah). Panels are at 23 degrees. The reason I placed panels on NW side and on the roof is that I did not need permission from my association and we use more power when we get from work/school and that is after 4PM. My reasoning on how to point panels was on how much I have in battery capacity and when most of the electric power is used.

    Leave a comment:


  • J.P.M.
    replied
    There is no one answer fits all situations. For the OP, if the grid cannot be used as a battery, and if one big goal is to lower an electric bill, two of the better options may be a combination of getting the best orientation of the array based on annual solar availability considering weather, and then time shifting of loads (another way of saying lifestyle adjustment) to use as much of the power generated onsite as possible. I guess the impact of no feed in tariff is one of those things that needs to be considered before any PV acquisition.

    For situations where some form of net metering is available, if T.O.U. is [U]not[/U] involved, the best orientation is probably the one that maximizes the annual system output. Depending on site shading and a couple other parameters like panel efficiency as f(panel temp.), that orientation is pretty close to the orientation that produces the maximum annual irradiance on an array taking weather and shading into account.

    If net metering is available and T.O.U. [U]is[/U] used or mandated, and the main goal is electric bill minimization, the best array orientation is one that maximizes the annual value of the power generated, expressed as the product of the power produced times the cost of that power at the time it is produced.

    In the case of the T.O.U. NEM situation, depending on the particulars of the T.O.U. schedule - particularly if it is a schedule that does not have a tier rate credit for the lower tiers laid over it - hourly system output from models of annual production such as PVWatts or others can be matched on a spreadsheet with the cost of electricity for corresponding hours to get a value for the "revenue" a PV array will produce under modeled conditions. That revenue, within the limitations imposed by annual weather variability, can be thought of in the same sense as a model's output can be used - as a dart throw for design purposes that will vary from year to year but over the long term probably be a fair representation of what to expect to maybe +/- 10 % or so in any one year.

    On the situation of being on T.O.U. and treating a PV array as a revenue generator, I've done the spreadsheet work for my situation for a bunch of array orientations, 90 to 270 deg. azimuth and 20 to 40 deg. tilts. Every geographic location will produce different results as will every tariff schedule, but for me only, the array orientation that produces the most revenue offset using my POCO's T.O.U. schedule for customers on NEM is an azimuth of ~ 205 deg. at an ~ 30 deg. tilt.

    FWIW, at my location that optimal orientation produces about $486 of annual bill offset revenue per installed STC kW of PV using PVWatts modeled output and the latest SDG & E billing schedule DR-SES. So, a 5 kW array will produce $486/STC kW* 5 kW = $2,430 that I then get to "spend" any way I choose regardless of how much electricity I used or when I used it. Because the T.O.U. NEM tariif is straight T.O.U.,the $2,430 "credit" is unaffected by my usage or the pattern of that usage.

    I've not checked (yet) that other locations in CA would produce similar optimal orientations with the optimal azimuth ~ 205 - 225 deg. and tilts a bit higher by 5- 10 deg. as the locations moved to N. CA.

    Leave a comment:


  • Mike90250
    replied
    I have one of my pole mounts aimed south, and the other aimed SE, to catch a bit more AM sun for power for the toaster.

    Leave a comment:


  • PNPmacnab
    replied
    All solar is local and depends on your needs. Some do east west panels. That provides more even power the entire day. If you have the space, panel price is no longer an issue. Panels are a better investment than batteries. By necessity, my panels are almost flat which gives a more even bad performance all day.

    Leave a comment:


  • nwdiver
    replied
    Originally posted by C.R.J. View Post
    Hi Forum,
    It seems obvious that south is the way to go.(for those in northern hemisphere anyway).
    So at mid-day the sun is at its height, and you get the best incidence to your panels, and you create the most power.
    So is this a waste when you are not there to use all of it? If you have a feed in tariff then all is well. If you don't have a feed in tariff, maybe it's wasted.
    Here in Spain, there is no feed in tariff. Very annoying! So if i am over producing for 2 or 3 months of the year, the excess power is wasted.
    Also here in Spain, our main meal of the day tends to be between 1:30 and 2:30 in the afternoon. So that would be our peak period for use of electricity, not at 12:00.
    Would it not be sensible to orientate the panels to produce peak power around the peak period of use? Granted there have to be limitations on the orientation.
    The orientation of the panels to other than south will obviously have a negative effect on the total kw/h produced daily/weekly/monthly ect
    Or perhaps the beer i consumed is clouding my judgment?
    From a supply/demand perspective West is better. Unfortunately there's no real benefit in most areas due to NEM. The last install I did was oversized by ~45% due to a service restriction on the inverter capacity. It was a ground mount so I had some discretion over orientation. I angled ~2/3rds slightly west and 1/3rd slightly east.

    Leave a comment:


  • Mike90250
    replied
    There are many good reasons to aim panels so they do you the most good. But generally, the expense to make special racks to aim differently than your roof plane faces, overwhelms the benefit of aiming precisely at 193 degrees.. Unless you are using a pole or ground mount system instead of the roof

    Leave a comment:


  • C.R.J.
    started a topic Is south the best direction for your panels?

    Is south the best direction for your panels?

    Hi Forum,
    It seems obvious that south is the way to go.(for those in northern hemisphere anyway).
    So at mid-day the sun is at its height, and you get the best incidence to your panels, and you create the most power.
    So is this a waste when you are not there to use all of it? If you have a feed in tariff then all is well. If you don't have a feed in tariff, maybe it's wasted.
    Here in Spain, there is no feed in tariff. Very annoying! So if i am over producing for 2 or 3 months of the year, the excess power is wasted.
    Also here in Spain, our main meal of the day tends to be between 1:30 and 2:30 in the afternoon. So that would be our peak period for use of electricity, not at 12:00.
    Would it not be sensible to orientate the panels to produce peak power around the peak period of use? Granted there have to be limitations on the orientation.
    The orientation of the panels to other than south will obviously have a negative effect on the total kw/h produced daily/weekly/monthly ect
    Or perhaps the beer i consumed is clouding my judgment?
Working...
X