Weather station for residential PV

[sensij]

J.P.M. Thank you!

Mounting went OK. I dropped a 1-5/8" galvanized fence post through the roof, plumbed it and secured it to a truss... it isn't going anywhere. I tried using a compass app to make sure it was facing true south, although I had a hard time finding a reference surface on the station that I trusted... it certainly isn't exact. I ended up just visually matching the azimuth of the array, which should be within a degree or two of south and good enough to get me going. Doubled up the flashing around the penetration with conventional vent pipe seals, an EPDM layer on top to protect the PVC layer underneath from UV.

The temperature sensor radiation shield (fan aspirated) is sitting a couple inches off the roof, about 8 inches north / upslope of the line of panels, somewhat west of the center of the array. The shingles are energy star, so the roof doesn't get quite as hot as it did with conventional shingles, although until I add a few thermistors (leaning towards Tartssensors at this point) I can't comment on the difference in temp under the array vs where the station is measuring it.

Data are stored in 1 min increments, but PVOutput's minimum interval is 5 so I'm manually averaging points before upload. I took some care to keep the average synchronized with the timestamps of my generation meter, and so far, it looks good. As I get deeper into it, I can build in some more robust synchronization checks. At some point, I'll probably build a database or find a hosting site more weather focused, but getting the irradiance data overlaid with the array power on PVoutput is a nice visual. Running the data through a diffuse fraction model and splitting it up into DNI/DHI is probably the first processing step I want to figure out. Once I'm confident in that, working through the HDKR with environmental contributions will be interesting.

The station didn't end up perfectly level, and I can see some some preference in the rain gauge tipping bucket, it takes about 5 ml to tip one way and about 6 ml to tip the other. I ran out of time before I could check those numbers against what the calibration should be. It is nice that they designed the radiation sensor mount to have its own leveling adjustment.

The wind cups are below the peak of the roof, and should do a decent job of representing the wind felt by the array. Although the cups are above the rain gauge, it isn't by much, and I wonder if measurement of the wind out of the south will be affected. I put the bird spikes in, but they are really close to the radiation sensor... probably doesn't make a difference, but having a surface that can reflect so close caught my attention (even if it is very small diameter and should produce very little specular reflection). The birds should prefer the power lines near my house, so I might just pull the spikes back out until it is clear they are needed.

You can see how sharply the ridge to the west of the house (and the trees on it) knock out the power in the late afternoon / evening. That will get worse as we get into spring, before cleaning back up again in summer. The shade gradually crawls across the entire array, so the generating power is incrementally dropping out one panel at a time, leading to the softer decline in overall array power compared to the sharp drop of the sensor.

I probably won't be able to get a station picture for another couple weeks, time at home during daylight hours is limited (tangentially, why TOU works so well for me!). I'm sure I made some non-optimal installation decisions, but tried to balance the serviceability and aesthetics, and still get an accurate representation of the conditions at the array.

[J.P.M.]

J.P.M. Thank you!

Mounting went OK. I dropped a 1-5/8" galvanized fence post through the roof, plumbed it and secured it to a truss... it isn't going anywhere. I tried using a compass app to make sure it was facing true south, although I had a hard time finding a reference surface on the station that I trusted... it certainly isn't exact. I ended up just visually matching the azimuth of the array, which should be within a degree or two of south and good enough to get me going. Doubled up the flashing around the penetration with conventional vent pipe seals, an EPDM layer on top to protect the PVC layer underneath from UV.

The temperature sensor radiation shield (fan aspirated) is sitting a couple inches off the roof, about 8 inches north / upslope of the line of panels, somewhat west of the center of the array. The shingles are energy star, so the roof doesn't get quite as hot as it did with conventional shingles, although until I add a few thermistors (leaning towards Tartssensors at this point) I can't comment on the difference in temp under the array vs where the station is measuring it.

Data are stored in 1 min increments, but PVOutput's minimum interval is 5 so I'm manually averaging points before upload. I took some care to keep the average synchronized with the timestamps of my generation meter, and so far, it looks good. As I get deeper into it, I can build in some more robust synchronization checks. At some point, I'll probably build a database or find a hosting site more weather focused, but getting the irradiance data overlaid with the array power on PVoutput is a nice visual. Running the data through a diffuse fraction model and splitting it up into DNI/DHI is probably the first processing step I want to figure out. Once I'm confident in that, working through the HDKR with environmental contributions will be interesting.

The station didn't end up perfectly level, and I can see some some preference in the rain gauge tipping bucket, it takes about 5 ml to tip one way and about 6 ml to tip the other. I ran out of time before I could check those numbers against what the calibration should be. It is nice that they designed the radiation sensor mount to have its own leveling adjustment.

The wind cups are below the peak of the roof, and should do a decent job of representing the wind felt by the array. Although the cups are above the rain gauge, it isn't by much, and I wonder if measurement of the wind out of the south will be affected. I put the bird spikes in, but they are really close to the radiation sensor... probably doesn't make a difference, but having a surface that can reflect so close caught my attention (even if it is very small diameter and should produce very little specular reflection). The birds should prefer the power lines near my house, so I might just pull the spikes back out until it is clear they are needed.

You can see how sharply the ridge to the west of the house (and the trees on it) knock out the power in the late afternoon / evening. That will get worse as we get into spring, before cleaning back up again in summer. The shade gradually crawls across the entire array, so the generating power is incrementally dropping out one panel at a time, leading to the softer decline in overall array power compared to the sharp drop of the sensor.

I probably won't be able to get a station picture for another couple weeks, time at home during daylight hours is limited (tangentially, why TOU works so well for me!). I'm sure I made some non-optimal installation decisions, but tried to balance the serviceability and aesthetics, and still get an accurate representation of the conditions at the array.

You're welcome. Sounds good so far. For me anyway, the station setup/location/decision making was a set of compromises with respect to placement and elevation and how the surroundings effect the sensor readings. To my way of thinking, the irradiation sensor leveling was more important than the rain bucket.

As I wrote prior, I believe the HDKR model seems to give me the best match to what the pyranometer reads. I had to remember to adjust for the station altitude above sea level and the pyranometer temp. correction and a few other things like approximate atmos. parallax for incidence angle corr. BTW, I believe my pyra. temp. corr. factor is a bit less than published, but can't quantify it as much as I'd like. Just another one of the variables I don't have enough equations for.

[JFinch57]

After much research I bought a Davis Vantage Vue for Christmas. Don't think I can add any solar measurements, but it's really cool tracking the rain and wind! There are imported models out there for 1/3 the price but you get what you pay for!

[sensij]

Jeff, nice... the Vue was tempting but I really wanted the irradiance.

Below are a few pictures. I was on the roof yesterday and found the sensor had become out of level, with a south facing tilt, consistent with J.P.M.'s comments on my data relative to others in the area. After yesterday's adjustment, I was still 2.5% higher than Boulder Knolls today, and I double-checked level at the end of the day and found no movement... I think it is as good as I'm going to get without coming up with a technique to directly measure the active surface of the sensor.

The sensor yesterday, prior to the correction (South is up).
As-found.jpg




A view showing the station positioning relative to the array (looking east): east view.jpg


The view looking south:
South view.jpg

[J.P.M.]

Thank you. More later.

J.P.M.

[J.P.M.]

Thank you.

02/14 was a decent day for sun, but not cloudless or completely clear around my house, somewhat different than Boulder Knolls ( "B/K") around solar noon. As you know, if "clear", readings around solar noon will tend to be quite stable w/1 min. interval readings that are quite stable, not varying more than a Watt/m^2 or two. Yesterday was one of those days around here (for me) that had clear sky readings bouncing around at ~ solar noon. B/K readings tended to be more stable. Today looks like it may be more stable.

My GHI at solar noon (actual 12:02:34 P.S.T. at my long.) was 708 W/m^2 uncorrected for temp. B/K @11:55/12:05 was 717 and 719 respectively.

@ 1100 hrs. we ( Me and B/K) were both at 684.

@ 1130 hrs., I was at 705, B/K was at 708.
@ 1230 hrs., I was at 684, B/K was at 707.
@ 1300 hrs., I was at 675, B/K was at 684.

I had some stuff I could see that rolled in about 1150 hrs. that seemed to not be around B/K even though its only ~ 1 1/4 miles away. The afternoon readings for me and B/K bounced around some as some scattered clouds rolled in.

I'm not too sure that your sensor being a bit out of plumb to the degree shown will be a big source of error. Ratio the cos (zenith angle) to cos (zenith angle+0.1 degrees) or so for an est. of possible error from off level.

The bigger suspect (if there is one - your data may well be as, or more accurate, than mine or anyone else's) in my mind is the light colored surface - the roof shingles - or at least that portion of the shingles that are above the level of the solar sensor and are thus "seen" by the sensor. They may well be adding a larger component of reflected and forward scattered (as seen from the shingles) diffuse irradiance than my roof which is brown concrete tile and in any case below the level of the sensor. You may also have some contribution from the upslope to your west.

A smaller issue at this time is what you do about correcting the irradiance sensor readings for sensor temp. I assume your data as published is not temp. corrected.

Thanx again,

J.P.M.

Add: the station will probably get out of plumb on a regular basis due to mean old Mr. Gravity. Mine's ballasted, guyed at the base and moveable, and I tweak/shim it about every 2-3 months', depending on season and wind/temp. induced creep.

[sensij]

I did note that the documentation for the sensor includes the following:

Temperature Coefficient . . . . . . . . . . . . . . . . . . . . . . . . . +0.067% per °F (+ 0.12% per °C)
Reference temperature . . . . . . . . . . . . . . . . . . . . . . 77°F (25°C)
Correction per degree above reference temp . . . . . . -0.067% of reading per °F (-0.12% per °C)
Correction per degree below reference temp . . . . . . +0.067% of reading per °F (+0.12% per °C)

I suppose I was uncertain if Davis had built the correction into the calibration of the system, or if I was expected to apply it myself (I don't, yet). I saw in another thread that you (@J.P.M) had commented with the temperature correction you were using, but I didn't check at that time to see how closely it aligned with Davis's information. What temp do you use, IR Pyrometer reading of the sensor? The station temp sensor is radiation shielded, while the irradiance sensor is not, so it seems like there could still be a few more degrees of rise on that sensor on a typical day. With measured rooftop temps at 95 deg F, let's say the sensor is 25-30 deg F above its 77 deg reference temp. That would be a correction of something like -1.5% to -2%... most of the difference between my sensor and the Boulder Knolls data.

Idle thought... have you considered mounting the Davis sensor at an orientation that matches the array, to measure POA irradiance directly and avoid the conversion approximations from GHI? Sensor location would matter... I'd probably want it on the south edge of the array so that light reflected from the array itself did not skew the numbers, but at the 18 deg tilt, it should be less sensitive to potential reflections from the north (or sensitive to them to the same degree the panels would be). I think the Envoy 8X would support a 2nd sensor+transmitter if both POA and GHI were desired, but the Envoy might not, I'll need make another pass at the documentation.

Edit... today is 10-15 deg F cooler than yesterday, but the mid-day differential between my system and Boulder Knolls is unchanged. From this, I would conclude that those data are also not temp corrected.

[J.P.M.]

I did note that the documentation for the sensor includes the following:



I suppose I was uncertain if Davis had built the correction into the calibration of the system, or if I was expected to apply it myself (I don't, yet). I saw in another thread that you (@J.P.M) had commented with the temperature correction you were using, but I didn't check at that time to see how closely it aligned with Davis's information. What temp do you use, IR Pyrometer reading of the sensor? The station temp sensor is radiation shielded, while the irradiance sensor is not, so it seems like there could still be a few more degrees of rise on that sensor on a typical day. With measured rooftop temps at 95 deg F, let's say the sensor is 25-30 deg F above its 77 deg reference temp. That would be a correction of something like -1.5% to -2%... most of the difference between my sensor and the Boulder Knolls data.

Idle thought... have you considered mounting the Davis sensor at an orientation that matches the array, to measure POA irradiance directly and avoid the conversion approximations from GHI? Sensor location would matter... I'd probably want it on the south edge of the array so that light reflected from the array itself did not skew the numbers, but at the 18 deg tilt, it should be less sensitive to potential reflections from the north (or sensitive to them to the same degree the panels would be). I think the Envoy 8X would support a 2nd sensor+transmitter if both POA and GHI were desired, but the Envoy might not, I'll need make another pass at the documentation.

Edit... today is 10-15 deg F cooler than yesterday, but the mid-day differential between my system and Boulder Knolls is unchanged. From this, I would conclude that those data are also not temp corrected.

Understood. I'll try to be brief and hopefully in the order asked.


I correct per the published Davis correction of -0.12%/deg. C. for my fouling estimate measurements, using the sensor temp. as the same as the station temp. Otherwise, sometimes I stick with the raw pyranometer reading for a lot of P.O.A. est., or do a temp. correction if the times/temps. are for example symmetric around solar noon, A.M - P.M. w/ similar zenith angles but diff. temps. It depends. My IR ther. I use for panel temp. measurements usually shows the irradiance sensor to be within a couple of deg. F of the station sensor most of the time, a bit higher at low/still winds, but bounces around +/- a bit, mostly around the station temp. At least the temps. change in the same general direction.

Being of a light color, low thermal mass and somewhat thermally isolated from its supports, and from some IR trer. temp. readings, I'm of the opinion that the irrad. sensor temp. is pretty close to the amb. air temp. More of the non exact science stuff.

I believe B/K does not correct for temp. as we usually differ by about the same % using my uncorrected readings. If their software corrects for temp., I can't see it. I also believe B/K may be out of plumb by about 0.2 - 0.4 deg. favoring an az. of ~ 220 - 260 deg. or so, but have no hard data. That guess is about 4 yrs. old anyway.

The irradiance sensor better not be radiation shielded as that's what it's measuring.

For a lot of reasons, and by convention, most irrad. measurements are done in the horiz. plane, with POA irrad. estimated from various models. Most of the reason has to do with keeping everyone on the same page. Another reason is the nature of diffuse radiation which is usually non isotropic. A non horiz. sensor will "see" the diffuse fraction differently, probably including its wavelength distribution, and perhaps become (more) inaccurate. I did indeed think about doing so but with an additional sensor, and then compare side/side, readings, keeping in mind the possible error discussed above. See the literature for more discussion. Davis told me that a solar sensor in the IR sensor slot won't work for a lot of reasons and I sort of lost interest anyway. I'll recheck the Envoy 8X blurbs.

I do still suspect your portion of the roof that's at a higher elevation than the irrad. sensor may be skewing your readings. Check the NREL Bird model (excel) and vary the albedo to see the effect on estimated GHI. Far from an exact or even accurate methaod, but perhaps interesting food for thought as to how a sensor on a white roof, some of which is visible to the sensor, might influence output. Just sayin'.

Are we having fun yet ?

[sensij]

Sunday afternoon I moved the weather station to the peak of the roof, to test the idea of uphill reflection affecting the result. Today might not have been the best day to compare... I'll probably leave it up there only a couple more days before moving it back... it isn't as secure as I'd like right now.

The anisotropy of the diffuse fraction does not seem to me like it would be a fatal flaw... *if* the active material of the pyranometer responded to that anisotropy in the same way as the Si panels. From what I understand, it probably does not. There is a certain satisfaction that comes from measuring and reporting the GHI and following in the footprints of those who have figured out how to transpose those data in useful ways for modeling.

Also, I should have mentioned earlier that when I made the out of plumb adjustment, I had finally removed the bird spikes. If the tilt doesn't explain the 2% or so change in reading after that, perhaps so reflection of those might fill in the gap.

I know that chasing every last % or so is likely to be a wild goose chase on an instrument with published +/-5% accuracy, but it is sort of neat to see how it responds to different installation conditions.

Edit...
Almost forgot, in the course of reading about this, I came across a nice discussion of the uncertainty of a pyranometer vs a PV reference cell hosted by NREL. I'm not sure how expensive they are, but that might be another path to fouling measurement, although it seems counter-intuitive to use a sensor to measure fouling that would probably be sensitive to the same fouling and degradation as the subject of the study.

http://www.nrel.gov/docs/fy12osti/55487.pdf

[J.P.M.]

Sunday afternoon I moved the weather station to the peak of the roof, to test the idea of uphill reflection affecting the result. Today might not have been the best day to compare... I'll probably leave it up there only a couple more days before moving it back... it isn't as secure as I'd like right now.

The anisotropy of the diffuse fraction does not seem to me like it would be a fatal flaw... *if* the active material of the pyranometer responded to that anisotropy in the same way as the Si panels. From what I understand, it probably does not. There is a certain satisfaction that comes from measuring and reporting the GHI and following in the footprints of those who have figured out how to transpose those data in useful ways for modeling.

Also, I should have mentioned earlier that when I made the out of plumb adjustment, I had finally removed the bird spikes. If the tilt doesn't explain the 2% or so change in reading after that, perhaps so reflection of those might fill in the gap.

I know that chasing every last % or so is likely to be a wild goose chase on an instrument with published +/-5% accuracy, but it is sort of neat to see how it responds to different installation conditions.

Edit...
Almost forgot, in the course of reading about this, I came across a nice discussion of the uncertainty of a pyranometer vs a PV reference cell hosted by NREL. I'm not sure how expensive they are, but that might be another path to fouling measurement, although it seems counter-intuitive to use a sensor to measure fouling that would probably be sensitive to the same fouling and degradation as the subject of the study.

http://www.nrel.gov/docs/fy12osti/55487.pdf

Understood. Thank you for the update and the paper. I Got through the 1st read. I usually takes 2 or 3 before I begin to understand what's written. I'm not sure I understand some of the reasoning. However, eq. (5) in that paper is the one I use as one estimate of the array temp. and compare it to actual array temp. readings I take, and also compare it to the est. array temps from inverter display voltage readouts. As I wrote, and bottom line for me, they all seem to be generally within a degree C. or two of one another w/an occasional flyer now and again. Figuring out how to manage/modify the wind vector is an ongoing piece of work and probably the source of a lot of uncertainty.

Some items.
1.) FWIW only, yesterday, 02/22/2016, and before doing a lot of fixturing work, and to see if further work might be fruitful, I put a plastic, flat white diffuse plastic of ~ 8" X 11" north of my sensor tilted at ~ 12 deg. off horiz. beginning at solar noon (@ 12:01:54 @ my location) for 3 minutes yesterday and noted the irradiance reading changes from 3 min. before solar noon. The post solar noon irrad. sensor readings w/ the white duffuser in place were 777 to 775 W/m^2. The 3 min. pre solar noon readings without the diffuser in place were 758 and 759 W/m^2. All this is SWAG and not precise, but it did lead me to some firmup of my guess that your white roof may be adding to your GHI reading. I note your output for about the same time was 779 W/m^2. Boulder Knolls was about 765 W/m^2 and that data seems to show the effect of some clouds we all saw. I'm thinking about a more stable fixture for the white diffuser scheme something like a small tilt table.

2.) I've always mused that a PV device like the Davis sensor might have an advantage over the thermopile devices in the sense that a PV device would be "seeing" the irradiance in more of the same way as a PV array or PV module would be "seeing" it, separate from any absolute accuracy. They're certainly a lot less expensive and require less care/maint.

3.) Putting a PV sensor device in place POA, while it no would no longer, by definition measure GHI, may be suitable for a swag at POA without the hassle and uncertainty of which algorithm to use to convert GHI to POA that gives the best match with real time reality. That's not to imply that the absolute accuracy of a device will be improved by a POA orientation. I'd think however, that it would be necessary to preface all presentation of data from a non horizontal sensor with careful notation of the actual sensor orientation.

FWIW, I intend to continue using the HDKR model and GHI as another talk w/ Davis yesterday confirmed that the UV sensor side can't be used w/ an additional solar sensor.

4.) I bought an additional sensor yesterday from Ambient Weather in AZ ($123 BTW) and will send the current sensor back to Davis for a re/calibration check. ($72 w/ shipping). I'll change them out (quickly ?) some very sunny solar noon around the summer solstice and get a SWAG on comparison. The recalibration went up a few bucks since last year. Davis said they used to sell a tilt table, but no one bought them. Fairly easy to make however. I thought about buying a Li-Corr device, but after seeing the price w/ a decent data logger and necessary other stuff/hassle, I'd buy another Davis device and use that if I was that curious about it. Maybe some day. Not this day. I'd love an Eppley PSP and have worked w/them many years ago but the cost/hassle for the return ain't worth it to me.

EDIT: On the fouling aspect, I clean the sensor before every measurement event. One way to think of what I'm doing is using published data for STC efficiencies, areas, temp. coeff. etc, AND estimates of the effective array temp. using weather station data at the array to estimate what the "clean" array output might be, including adjustments for inverter eff., and a 1% complete, but consistent SWAG for line losses. Then compare that to the actual output with the same adjustments. If I then back out or adjust what the irradiance would need to be for a clean array to have the same output as the actual, measured output, that lower irradiance compared to the measured irradiance is a measure of how much solar irradiance (without respect to wavelength) has been reduced by the dirt covering the front surface of the array. That's the simple way it works out. On a more fundamental level, the nature of the fouling is such that it may well provide a slight insulating effect on the array, increasing the array temp. slightly, or, change the effective surface reflectance some as f(wavelength) or, be non uniform as in a bathtub ring often present on fouled arrays, or a bunch of other stuff that may/may not be significant. Interesting stuff, but perhaps more useful for senior engineering projects than immediate practical use.

[sensij]

It appeared to be about as clear as it gets today with mid-day irradiance reported by my sensor at ~791, while Boulder Knolls was 778 W/m2. 1.7% difference in this location, with my sensor at the peak of the roof. I'll move it back to pole mount soon, and at this point expect to add maybe 1% more to the difference (maybe slightly more because of temp), which looks attributable to the reflective roof from this test and the results J.P.M. has posted. Food for thought on how to deal with that... just offset the reading, or see if there is a way to keep the extra reflection from affecting the sensor.

The Li-Cor device looks like an interesting alternative... not inexpensive, and neat that their brochure shows one mounted directly to the frame of a tilted PV panel. I've got enough work to do to get the data processing built around this stream before adding to it, though.

From what I've gathered about the Davis architecture, the UV sensor slot could still be useful, although not as a direct source of data. The four pins available from that slot are meant for power, signal, and common (2x). The signal line is a dead end, because the processing done by either the transmitter or receiver kills the resolution of the measurement. The +3V and common would still be appropriate to power another irradiance sensor, but I'd have to build my own voltage monitoring and reporting of the signal output, and probably have it mounted next to the existing sensor for a couple weeks to get the calibration to match. Another project to add to the bottom of the list.

[J.P.M.]

It appeared to be about as clear as it gets today with mid-day irradiance reported by my sensor at ~791, while Boulder Knolls was 778 W/m2. 1.7% difference in this location, with my sensor at the peak of the roof. I'll move it back to pole mount soon, and at this point expect to add maybe 1% more to the difference (maybe slightly more because of temp), which looks attributable to the reflective roof from this test and the results J.P.M. has posted. Food for thought on how to deal with that... just offset the reading, or see if there is a way to keep the extra reflection from affecting the sensor.

The Li-Cor device looks like an interesting alternative... not inexpensive, and neat that their brochure shows one mounted directly to the frame of a tilted PV panel. I've got enough work to do to get the data processing built around this stream before adding to it, though.

From what I've gathered about the Davis architecture, the UV sensor slot could still be useful, although not as a direct source of data. The four pins available from that slot are meant for power, signal, and common (2x). The signal line is a dead end, because the processing done by either the transmitter or receiver kills the resolution of the measurement. The +3V and common would still be appropriate to power another irradiance sensor, but I'd have to build my own voltage monitoring and reporting of the signal output, and probably have it mounted next to the existing sensor for a couple weeks to get the calibration to match. Another project to add to the bottom of the list.

Thank you.

To be complete and honest, we may be trying to separating fly crap from pepper here. FYI and to keep you up to date, I did the same, crude tilted white diffuser method today as from prior today at 11:57:37 until 12:01:37 (solar noon at my location). Still crude hand held method as prior. The enhanced output GHI for that period was a steady 772 W/m^2. The 5 min. of readings after that, and thus approx. symmetric around solar noon were 765 to 763 W/m^2. So, enhancement was less this test. Confirm Boulder Knolls 12:00 -12:05 was 777 -779 W/m^2 respectively.

The NREL Bird model for my location using 1.6 cm. precip. H2O, from Reitan est. using ground dew point, .ozone at .1 cm. and broadband aerosol optical depth at .116 from TMY 3 for Miramar pukes out a GHI ~ 752 - 753 W/m^2 w/ 85% forward scattering and 0 albedo. To get to 790 W/m^2, the Bird model needs an albedo of about 50%.

I don't have any fixed love for my irrad. measurements, but they do seem to be reasonable with all the fouling measurements I've done in the sense the data seems to hold together better than I expected when I started the whole business. At the same time I'm under no illusions we have no better than semi - pro instruments and everything is +/- a bunch most of the time. My data is no better/worse than yours. I'll see what happens when the new sensor gets hooked up, probably at solar noon on the summer solstice.

Getting the sensor above most of the surroundings and putting a flat (non specular) darker color collar around the instrument can help reduce the albedo, but probably mucks up all the other readings like temp. and wind vector. Keeping it higher than the immediate surroundings is the best method. Both our instrument locations aren't AMS proper anyway.

More later.

[sensij]

Quick update for those interested... I've moved out of my home, and my systems are all in a period of transition. For those who have questioned in the past my insistence on keeping upfront costs low for PV systems, unplanned changes like this are a big wild card in any plan.

The PV monitoring will be coming back online without the revenue grade meter once the house has internet again next week... the SolarEdge inverter will be the source of generation data, with the understanding that it overreports to PVOutput by 1% or so.

The weather station will continue to remain with the array, until I get an array installed on the new house (probably in the next year or two... before 2019, in any case). It too should resume outside reporting next week.

[SunEagle]

Quick update for those interested... I've moved out of my home, and my systems are all in a period of transition. For those who have questioned in the past my insistence on keeping upfront costs low for PV systems, unplanned changes like this are a big wild card in any plan.

The PV monitoring will be coming back online without the revenue grade meter once the house has internet again next week... the SolarEdge inverter will be the source of generation data, with the understanding that it overreports to PVOutput by 1% or so.

The weather station will continue to remain with the array, until I get an array installed on the new house (probably in the next year or two... before 2019, in any case). It too should resume outside reporting next week.

I hope the move is easy and painless for you. Keep us informed on the situation.

[J.P.M.]

Quick update for those interested... I've moved out of my home, and my systems are all in a period of transition. For those who have questioned in the past my insistence on keeping upfront costs low for PV systems, unplanned changes like this are a big wild card in any plan.

The PV monitoring will be coming back online without the revenue grade meter once the house has internet again next week... the SolarEdge inverter will be the source of generation data, with the understanding that it overreports to PVOutput by 1% or so.

The weather station will continue to remain with the array, until I get an array installed on the new house (probably in the next year or two... before 2019, in any case). It too should resume outside reporting next week.

Thank you. I was wondering what was going on w/ your output.

As a current and sounds like soon to be former PV solar owner, any thoughts on if/what type of solar devices, if any, you might have in mind for the future ? Same installer ? Things to do differently ? Any expected/possible HOA PITA's ? Other thoughts on the buying/ownership experience ? Did you put a "does not convey" sign/proviso on the Davis ? How's the solar avail. at the (presumed) new residence ?

Buying in my neighborhood ????

Inquiring minds want to know.

Good Luck.

J.P.M.