36KW Solar Array - 225 Anderson Rd, Butler PA 16002
Daily Average: 111.21 kWh Past 2 Weeks: 119.84 kWh



Power: 0 W
Daily yield: 14.89 kWh
Total yield: 29631.29 kWh
Grid status: --.-- kWh


Data for the new 36KW array located 25 miles due north of Pittsburgh PA. This location is at about 40.75 degrees N latitude.


This is the second location that we have owned. The first array (20KW) at our prior residence about 40 miles SE of here served us flawlessly for 10 years and generated nearly 1/4 gigawatt. It continues in full operation. Both of these systems were installed by EIS Energy Independent Solutions Pittsburgh, PA. We would build more if the regulations and procedures would allow.

The ground mounted system is preferred because it not only allows the array to be optimally positioned and more easily serviced, it allows the panels to run cooler and therefore more efficiently; This avoids the issue with maintaining or replacing the roof on the residence; And, it also does not put the home at risk due to fire resulting from any fault of the high powered electrical systems involved.

Panels are fixed at a 30-degree angle and aimed due South. While additional power may be gained by tracking the Sun, any mechanical movement would involve additional hardware and present an ongoing maintenance concern. If more power is desired the preferred solution is to add more panels. If anything could be done to improve performance it would be to add some form of passive cooling. The lower the temperature the more efficient the panels become and the more power will be generated.

This system uses 100 Heliene 360W panels connected to 4 SMA SunnyBoy 7.7-US-41 grid connected inverters. The power used by the residence is independently monitored by an EKM Omnimeter Pulse UL v.4 meter.

Data Monitoring

The energy status of the system is monitored every 10 seconds by an INTEG Model 410 JNIOR. This device collects inverter status through network connection and the MODBUS protocol. It reads the residence status through an RS-485 connection. The resulting data is made available on-demand through the JNIOR web server as a single JSON packet.

A Ubuntu Linux based server in the residence collects data from the JNIOR every 10 seconds. This information is stored in a MySQL database. The Apache2 web server then presents the dynamic page that you are now viewing. Our database contains over 10 years of similar data from the prior solar plant.

Power (W)

The instantaneous amount of power in Watts (W) being generated by the array at this moment in time. This varies dramatically as to the quality of sunlight, angle of the Sun and the amount of cloud cover. Panels may even be covered with snow during winter months.

Daily yield (kWh)

The total amount of power in kilowatt hours produced during the current day. This resets to 0.00 at midnight. Our daily goal here is to more than cover the power used by the residence in the prior day. Hopefully we can consistently do so through most weather conditions and throughout the winter months.

Total yield (kWh)

The total amount of power generated by the array over all time in kilowatt hours.

Grid status

Indicates how much power the property has exported (credit) or consumed (used) over all time. Grid status started at 0 on May 25, 2022 prior to solar operation but after installation. This might have been initialized with the total power ever used by the property over the past 20 years if that number were known.

The total power used by the residence is deducted from that generated by the array in calculating the Grid status.

Currently the power company (West Penn Power) accounts for incoming (nighttime) and outgoing (daytime) power accumulating a bank of kilowatt hours through the year. When the exported power exceeds that used during the billing cycle only the company's monthly delivery and line charges apply (typically less than $8) and are deducted from any dollar credit on the account. Banked kilowatt hours are converted to dollars annually around June. A dollar credit builds on the account and may be reimbursed.


The reported 'Daily Average' is the average power generated for full days of operation excluding any early testing and excluding the current day. The average for days in the 'Past 2 Weeks' excluding the current day is also reported. The difference can be used to establish any current trend. This should tend to follow the annual pattern of the amount of available daily sunlight as we travel from solstice to solstice.


The battery displayed is a simulation allowing us to determine an ideal capacity for use in future off-grid operation. Or rather, operation not dependant on the grid while allowing the system to export excess power. The battery can easily be sized to maintain the residence through the night. Being able to insure power for the house after a week of dreadful solar performance is quite another matter. There is also a dramatic difference between winter and summer operation. The latter including air conditioning. Note that the residence currently heats with natural gas.

Top 100

This displays the top 100 production days (once we have operated for 100 days) in order from our record day down. Days within the past 2 weeks are highlighted. This list is dynamically updated as a day's performance might move up the list. Note that records are set on exceptionally clear days with the Sun high in the sky and during cooler temperatures. This typically occurs during late April and May.

Temperature dramatically affects panel efficiency. During hot summer months we may not reach maximum power capabilities. This is one reason why a roof mounted system is less desirable. This 36KW array is ground mounted and located so as to allow both optimum sun exposure and to make good use of the prevailing winds for cooling.

Off Record Pace

At any given moment during the day the total power generated by the array is reported. The 'Off Record Pace' shows the difference between the power generated today and that of the best performance day, our record day, in kWh at the same point in the day. The record day, Top 100 #1 day, is shown ghosted in the above chart.

A positive (+) value indicates that today is ahead of the record pace and barring cloud cover is making a run at the record. More typically this value will be negative (-) providing a feeling as to where the day might end up in the Top 100 table.


The larger chart graphs the instantaneous power (left scale) and the total daily power (right scale) during the key portion of the day. The record production day is shown as a ghost in the background.

The current power used by the residence (house) is charted below the main chart. The ghosted data in this chart represents the prior day.

Cloud Effects

On a perfectly clear day with a beautiful blue sky, a smooth bell curve shape power curve is expected. This begins at sunrise and continues until sunset barring any shade from hills and trees at the horizons. The performance is highly dependent on the time of year depending on sun angle and duration of the day. It is also very dependent on temperature. It is not surprising that our best production occurs in the spring when the daylight lengthens but the temperatures have yet to give up the winter chill.

Clouds block the sunlight and impact solar production. On a partly cloudy day the clouds line up and pass in sequence in front of the bright Sun causing great variation in the solar curve. This can often create quite a bit of "coloring" in our curve above. On an overcast day the solar power levels are (sadly) more consistently down.

Of interest is that sunlight on a cloudy day can reach the panels by indirect routes and actually augment power generation. The sunlight can be more focused onto our array through reflection from nearby clouds and by general bending of the light through the moisture suspended high in the sky. This can be referred to as cloud lensing. The result is quite evident in our curves as power pushes above the blue sky bell curve. In fact this often pushes the inverters to their 31.4KW maximum allowable power output. There is a warning evident in the curve of a oncoming cloud as it first pushes power levels up with reflected sunlight before getting in the way dropping power.

Is it possible that our ultimate Top 100 #1 record might come about on a cloudy day where, luck might have it, all of the clouds run north and south of the Sun's path providing power enhancing reflections but never blocking?

Top 100
130-Mar-2023 249.47 kWh
212-Aug-2022 244.20 kWh
320-Mar-2023 244.14 kWh
426-Mar-2023 240.64 kWh
508-Mar-2023 233.46 kWh
615-Mar-2023 233.23 kWh
707-Mar-2023 232.80 kWh
818-Aug-2022 230.83 kWh
903-Aug-2022 227.25 kWh
1024-Aug-2022 225.49 kWh
1130-Jul-2022 223.53 kWh
1219-Aug-2022 222.80 kWh
1301-Sep-2022 220.52 kWh
1410-Jul-2022 219.05 kWh
1505-Oct-2022 218.64 kWh
1628-Aug-2022 217.11 kWh
1709-Oct-2022 216.04 kWh
1815-Jul-2022 214.67 kWh
1909-Sep-2022 213.73 kWh
2015-Sep-2022 211.16 kWh
2120-Jul-2022 210.39 kWh
2214-Jul-2022 209.95 kWh
2318-Feb-2023 209.39 kWh
2423-Aug-2022 208.85 kWh
2523-Sep-2022 208.21 kWh
2611-Jul-2022 207.75 kWh
2709-Mar-2023 207.54 kWh
2820-Sep-2022 207.40 kWh
2919-Jul-2022 206.73 kWh
3021-Mar-2023 205.98 kWh
3111-Oct-2022 205.90 kWh
3212-Jul-2022 202.76 kWh
3315-Oct-2022 201.62 kWh
3420-Aug-2022 199.22 kWh
3521-Oct-2022 198.40 kWh
3622-Jul-2022 197.03 kWh
3716-Mar-2023 195.15 kWh
3811-Aug-2022 195.02 kWh
3905-Mar-2023 194.88 kWh
4023-Oct-2022 194.35 kWh
4113-Aug-2022 194.33 kWh
4231-Aug-2022 194.05 kWh
4327-Aug-2022 193.99 kWh
4413-Feb-2023 193.80 kWh
4501-Mar-2023 193.49 kWh
4624-Oct-2022 193.37 kWh
4722-Oct-2022 192.55 kWh
4829-Oct-2022 192.46 kWh
4925-Jul-2022 191.49 kWh
5013-Jul-2022 191.02 kWh
5126-Feb-2023 187.16 kWh
5211-Feb-2023 186.88 kWh
5302-Sep-2022 185.11 kWh
5425-Aug-2022 182.28 kWh
5510-Oct-2022 182.13 kWh
5608-Nov-2022 181.45 kWh
5717-Aug-2022 181.29 kWh
5801-Feb-2023 181.10 kWh
5924-Jul-2022 180.59 kWh
6014-Sep-2022 180.34 kWh
6116-Sep-2022 180.14 kWh
6207-Nov-2022 179.70 kWh
6309-Jul-2022 179.58 kWh
6417-Sep-2022 179.28 kWh
6526-Jul-2022 177.30 kWh
6602-Mar-2023 175.68 kWh
6714-Oct-2022 173.84 kWh
6803-Oct-2022 173.62 kWh
6918-Sep-2022 173.12 kWh
7003-Nov-2022 172.78 kWh
7121-Jul-2022 171.53 kWh
7209-Nov-2022 171.49 kWh
7321-Nov-2022 171.23 kWh
7424-Sep-2022 170.93 kWh
7527-Oct-2022 169.56 kWh
7620-Oct-2022 169.14 kWh
7712-Feb-2023 168.32 kWh
7810-Nov-2022 166.64 kWh
7916-Aug-2022 166.37 kWh
8023-Feb-2023 164.29 kWh
8126-Aug-2022 163.49 kWh
8215-Feb-2023 161.33 kWh
8322-Nov-2022 161.13 kWh
8426-Nov-2022 157.07 kWh
8515-Jan-2023 155.57 kWh
8623-Jul-2022 155.41 kWh
8723-Nov-2022 154.94 kWh
8826-Sep-2022 154.71 kWh
8904-Feb-2023 153.96 kWh
9020-Nov-2022 153.82 kWh
9104-Nov-2022 149.66 kWh
9221-Sep-2022 148.41 kWh
9308-Jul-2022 148.33 kWh
9408-Oct-2022 146.25 kWh
9502-Aug-2022 145.74 kWh
9629-Mar-2023 145.57 kWh
9705-Dec-2022 143.34 kWh
9824-Nov-2022 143.03 kWh
9908-Feb-2023 143.02 kWh
10016-Jan-2023 142.64 kWh