August 28, 20233 yr I've been running my PV array of 5500watts for about 3 months now and am dead chuffed with how well it's worked (once dialed in). Because I'm a monitoring nut, I noticed that on clear skies, my production would be less than in the beginning. I've hit 5000watts on a few occasions, but would normally hit the mid to high 4000's pretty easily, not lately though. I started looking into logs and noticed a few 100watts over time. First check was the panels themselves and noted a pretty thick layer of dust on them. I hosed off everything quickly and saw my production go up 1-200watts. So I decided this weekend to get out the floorwizz with a new head and a long-assed broom and cleaned them properly.......since Saturday my production has increased by an average of about 450-500watts. I know in summer we'll have the rain, but I think that I need to work it into my routine every 4 months or so.
August 28, 20233 yr 16 minutes ago, flatfourfan said: but I think that I need to work it into my routine every 4 months or so. It's a lot less effort to just install extra panels to compensate...
August 28, 20233 yr Part of the increase is the cooling of the panels - probably more than the actual cleanliness. Its not a bad idea if you can do it relatively effort-free
August 28, 20233 yr Author 25 minutes ago, mzezman said: Part of the increase is the cooling of the panels - probably more than the actual cleanliness. Its not a bad idea if you can do it relatively effort-free The numbers were actually checked the following day, i get what you're saying if they were taken immediately thereafter though. There was a post for a commercial set up a few years back, they had lost 20-30% because of dust. I believe that they were in the eastern side of Pta next to Hans Strydom.
August 28, 20233 yr 54 minutes ago, flatfourfan said: The numbers were actually checked the following day, i get what you're saying if they were taken immediately thereafter though. There was a post for a commercial set up a few years back, they had lost 20-30% because of dust. I believe that they were in the eastern side of Pta next to Hans Strydom. Just my 2c. Not too sure that dust alone can reduce output by 20-30%. Not all clear days yield the same irradiation. Some days the blue sky has a smoggy colour and on those days one can see lower yields. If you are getting close to or above 80% this time of the year you are doing pretty well and better than most. Want something more to test? Look at the forecast air quality in your area and combine it with clear skies and add the wind speed as cooler days and wind for cooling does affect the output too. Today during peak we had a higher than normal wind speed of about 4-7 m/s. Edited August 28, 20233 yr by Scorp007
August 28, 20233 yr 13 minutes ago, Scorp007 said: Want something more to test? Look at the forecast air quality in your area and combine it with clear skies and add the wind speed as cooler dags and wind for cooling does affect the output too. Today during peak we had a higher than normal wind speed of about 4-7 m/s. Aha! Very interesing. Thanks.
August 28, 20233 yr Agree with scorp007 some days or weeks or seasons can be more smoggy then others so you will get good and bad days , weeks , month and season . I only ones ever cleaned my panels in years of having solar and there was no noticable difference in performance after I cleaned them and I also keep an close eye on production . A friend has lots of high trees and so they have to weekly go up and clean there panels if leaves Can't see dust will reduce performance by 20%
September 7, 20232 yr Author On 2023/08/28 at 2:52 PM, Scorp007 said: Just my 2c. Not too sure that dust alone can reduce output by 20-30%. Not all clear days yield the same irradiation. Some days the blue sky has a smoggy colour and on those days one can see lower yields. If you are getting close to or above 80% this time of the year you are doing pretty well and better than most. Want something more to test? Look at the forecast air quality in your area and combine it with clear skies and add the wind speed as cooler days and wind for cooling does affect the output too. Today during peak we had a higher than normal wind speed of about 4-7 m/s. some good points there. I checked out my logs with some previous weather info and I think that you're onto something. While it was clear skies on both days, the one day the "clear-sky index" (yes I had to read up on this as I didn't know how it was measured...lol). was better on the following day and there was also a 20kph wind from the west that wasn't there the day before.....................imagine that.... Overall, I've been getting anything from 75-95% of the 5500 array and generating around 17kwh on a bad day to 27kwh on a great day and around 21kwh ish in the middle on days where we're not home....If summer gets me even better numbers, then I guess I don't have much to complain about........lolz. Thanks for the input....
September 7, 20232 yr 6 minutes ago, flatfourfan said: some good points there. I checked out my logs with some previous weather info and I think that you're onto something. While it was clear skies on both days, the one day the "clear-sky index" (yes I had to read up on this as I didn't know how it was measured...lol). was better on the following day and there was also a 20kph wind from the west that wasn't there the day before.....................imagine that.... Overall, I've been getting anything from 75-95% of the 5500 array and generating around 17kwh on a bad day to 27kwh on a great day and around 21kwh ish in the middle on days where we're not home....If summer gets me even better numbers, then I guess I don't have much to complain about........lolz. Thanks for the input.... Normally one can get an easy 33kWh in summer provided you have enough load or batteries that are not full. 6kWh on a clear summer day per 1kW of PV is achieved by a lot of people in Gauteng at around 25 deg tilt.
September 7, 20232 yr Author 27 minutes ago, Scorp007 said: Normally one can get an easy 33kWh in summer provided you have enough load or batteries that are not full. 6kWh on a clear summer day per 1kW of PV is achieved by a lot of people in Gauteng at around 25 deg tilt. Those numbers are hella encouraging.............Yup, in winter i would start my day on 25% storage, but as it's getting warmer and I don't need to run the geysers in the morning to "top up" I'm starting my mornings on about 60% so my dream of pulling more in summer seems to be fading somewhat. Perfect time to buy some AC units I'd say. The best part is last week we pulled a total of 3kWh from eksdom for the whole week and actually had multiple days with zero draw from them.
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