6kW system in Agoura Hills

[s_man]

I used a local solar company, they are not big but are in this business for 3+ years, very responsive, I signed the contract a week ago and the panels are done today. I can PM you more details if you're interested. Negative on the variable speed pool pump, based on my estimates 9kW should be barely enough to 0-out my current bill on TOU/net-metering, the old pump is staying for now as a ballast that I can through out should my production drop over time or usage increase. Yes, I know this is not the smartest approach, but it works for me.

EDIT: PM sent

Gvl, could you share your installer's information? Thanks!

[gvl]

it makes perfect sense, especially after shelling out for solar. If your system produces enough maybe you won't need to upgrade your pump

Well, the pump upgrade up front would probably have saved me $1.5k upfront overall as I could get a smaller array, but since the savings from the pump were unknown I decided to err on the safe side and just pay for extra solar. Plus replacing a pump could chain react into additional costs potentially, like broken fragile 20 year old PVC pipes, new electrical runs, etc.

[MikeInRialto]

it makes perfect sense, especially after shelling out for solar. If your system produces enough maybe you won't need to upgrade your pump

[gvl]

Who did you use for the install?

And have you gotten the variable pool pump yet? A variable makes a world of difference ($50-60 less/month) - I am running mine for 8 hours a day: 4 hours at 280 watts and then another 4 hours at 380 watts = 2640 watts per day giving me a 1.2 Turn over rate... I might crank it up a bit more when we hit 90+ temps. And yes, they are VERY quiet!

I used a local solar company, they are not big but are in this business for 3+ years, very responsive, I signed the contract a week ago and the panels are done today. I can PM you more details if you're interested. Negative on the variable speed pool pump, based on my estimates 9kW should be barely enough to 0-out my current bill on TOU/net-metering, the old pump is staying for now as a ballast that I can through out should my production drop over time or usage increase. Yes, I know this is not the smartest approach, but it works for me.

EDIT: PM sent

[MikeInRialto]

Who did you use for the install?

And have you gotten the variable pool pump yet? A variable makes a world of difference ($50-60 less/month) - I am running mine for 8 hours a day: 4 hours at 280 watts and then another 4 hours at 380 watts = 2640 watts per day giving me a 1.2 Turn over rate... I might crank it up a bit more when we hit 90+ temps. And yes, they are VERY quiet!

[gvl]

Well, the panels were installed today. Final inspection and PTO pending. Ended up going with 9kW total at $3.17/watt. LG300s with a SE 10k inverter, P400 optimizers. It took 1 day for 7 people. I'm not a big fan of 1 day projects like this but I think it went reasonably well, but only time will tell of course.

[gvl]

Now considering ground mount, started a new thread: http://www.solarpaneltalk.com/showth...unt-vs-rooftop

[J.P.M.]

I can see homes further away from the hills getting sunshine in the morning while my street gets none, isn't it enough to say that sun elevation angles are less than that of the hills? I think they either didn't use the tool correctly or it is an inherent limitation of the tool.

EDIT: they just got back to me saying sun access is 97%, I suppose they may have considered it as no shading as compared to other situations and it is close to my pvwatts hourly analysis

That 97% access sounds not too much different than we were guessing some posts back +/- a bit.

One more time: This ain't rocket science.

[gvl]

If the max. hill elevation angles are less than the solar elevation angle for the corresponding azimuth angle, the hills will not cast a shadow at the location of interest. Get a sun path diagram for your location for Dec. 21 that shows solar elevation angles as f(time) and measure (estimate) the hill elevation angles with a protractor. Compare the two.

I can see homes further away from the hills getting sunshine in the morning while my street gets none, isn't it enough to say that sun elevation angles are less than that of the hills? I think they either didn't use the tool correctly or it is an inherent limitation of the tool.

EDIT: they just got back to me saying sun access is 97%, I suppose they may have considered it as no shading as compared to other situations and it is close to my pvwatts hourly analysis

[J.P.M.]

They performed SunEye measurements today and say there is no shading, I know there is. Should SunEye have picked up 3-5% early morning shading due to moderate hills a mile or so from home? I suppose it may be due to the deficiencies of the tool, like it can detect a shade from a tree or a house nearby, but the hill contours are pretty low and not as contrasty so they go undetected.

If the max. hill elevation angles are less than the solar elevation angle for the corresponding azimuth angle, the hills will not cast a shadow at the location of interest. Get a sun path diagram for your location for Dec. 21 that shows solar elevation angles as f(time) and measure (estimate) the hill elevation angles with a protractor. Compare the two.

[gvl]

Among other things, PVWatts doesn't use daylight savings time. What it thinks is 6:00, is 7:00 right now. I would suggest getting a better understanding of that tool before using it this way. Get a good shade analysis, ask an installer to preform a SunEye measurement at your installation site.

They performed SunEye measurements today and say there is no shading, I know there is. Should SunEye have picked up 3-5% early morning shading due to moderate hills a mile or so from home? I suppose it may be due to the deficiencies of the tool, like it can detect a shade from a tree or a house nearby, but the hill contours are pretty low and not as contrasty so they go undetected.

[J.P.M.]

Thanks, considering the DST it is not as bad then. Still learning...



Turns out it is even less, considering my math is not too much off. For a 8.1kWh DC array PVWATTS estimates 12,031kWh annual AC energy. I came up with only 415kWh AC generated (3.4%) for the next 2 hours after the last 0-reading in the morning, more like first 1.5hr of sun on average? Assuming P(H) is the first non-0 predicted power output this is the formula I used for a daily estimate:

Energy = P(H) / 2 + (P(H) + P(H + 1)) / 2

I don't remember your az./tilt, and each sit. is diff., but for my array in zip 92026, 118.75 deg. tilt, 195.75 deg. az. :

Using SAM #'s (TMY3, Miramar), yearly long term est. as % of yearly total output with no shading by (365 ) hr. increments ending each day at:

0600 P.S.T: 0.04% of year's total. (<4 kWh/yr.)
0700 P.S.T. 0.7% of year's total.
0800 P.S.T. 3.2 % of year's total.
0900 P.S.T. 6.9 % of year's total.

Your mileage will vary from mine and they'll both vary year/year. While your hourly % will vary from mine for your location, I'd guess the general trend may be similar.

PVWatts output for your location is left as an exercise for the reader.

Looks like they might be close given your 3.4% #. It is, after all, no more than an estimate.

[gvl]

Among other things, PVWatts doesn't use daylight savings time. What it thinks is 6:00, is 7:00 right now. I would suggest getting a better understanding of that tool before using it this way. Get a good shade analysis, ask an installer to preform a SunEye measurement at your installation site.

Thanks, considering the DST it is not as bad then. Still learning...

OK, try this:

1.) Run PVWatts with correct orientation.
2.) Use the hourly output.
3.) Download to a spreadsheet.
4.) Get the totals of hourly output for each hour of a TMY, or for the first few hours as needed.

My guess is the first hour's total estimated total output for the year will be something like 5-8% of year's total estimate for all hours, +/- a bit.

Turns out it is even less, considering my math is not too much off. For a 8.1kWh DC array PVWATTS estimates 12,031kWh annual AC energy. I came up with only 415kWh AC generated (3.4%) for the next 2 hours after the last 0-reading in the morning, more like first 1.5hr of sun on average? Assuming P(H) is the first non-0 predicted power output this is the formula I used for a daily estimate:

Energy = P(H) / 2 + (P(H) + P(H + 1)) / 2

[J.P.M.]

It's more than 1hr I'm afraid. For example today PVWATTS thinks I should be generating 0kW@5am, 1.5kW@6am, 3.2kW@7am, and 4.7kW@8am AC from a 8kW DC system, and there was absolutely no sun on the roof until 7:30. Approximating linearly I would miss about 5kWh of production today. I don't know how this will be distributed over all months, but I suspect the duration of shading will not be constant.

OK, try this:

1.) Run PVWatts with correct orientation.
2.) Use the hourly output.
3.) Download to a spreadsheet.
4.) Get the totals of hourly output for each hour of a TMY, or for the first few hours as needed.

My guess is the first hour's total estimated total output for the year will be something like 5-8% of year's total estimate for all hours, +/- a bit.

[sensij]

Among other things, PVWatts doesn't use daylight savings time. What it thinks is 6:00, is 7:00 right now. I would suggest getting a better understanding of that tool before using it this way. Get a good shade analysis, ask an installer to preform a SunEye measurement at your installation site.