36KW Solar Array - 225 Anderson Rd, Butler PA 16002
Daily Average: 123.63 kWh Past 2 Weeks: 219.22 kWh



Power: 0 W
Daily yield: 112.72 kWh
Total yield: 41442.56 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
109-Apr-2023 252.66 kWh
226-May-2023 252.36 kWh
319-Apr-2023 252.12 kWh
417-May-2023 251.58 kWh
515-May-2023 250.45 kWh
630-Mar-2023 249.47 kWh
710-Apr-2023 249.37 kWh
812-Aug-2022 244.20 kWh
920-Mar-2023 244.14 kWh
1027-May-2023 243.22 kWh
1111-May-2023 242.06 kWh
1214-May-2023 241.56 kWh
1326-Mar-2023 240.64 kWh
1413-Apr-2023 239.47 kWh
1521-May-2023 239.31 kWh
1609-May-2023 237.81 kWh
1731-May-2023 237.72 kWh
1818-May-2023 237.09 kWh
1912-Apr-2023 235.71 kWh
2030-May-2023 235.25 kWh
2101-Jun-2023 234.43 kWh
2208-Mar-2023 233.46 kWh
2315-Mar-2023 233.23 kWh
2407-Mar-2023 232.80 kWh
2511-Apr-2023 232.70 kWh
2618-Aug-2022 230.83 kWh
2706-May-2023 230.41 kWh
2825-May-2023 229.32 kWh
2927-Apr-2023 229.11 kWh
3029-May-2023 228.96 kWh
3122-May-2023 227.54 kWh
3203-Aug-2022 227.25 kWh
3305-May-2023 226.14 kWh
3424-Aug-2022 225.49 kWh
3530-Jul-2022 223.53 kWh
3619-Aug-2022 222.80 kWh
3701-Sep-2022 220.52 kWh
3820-Apr-2023 220.31 kWh
3904-Jun-2023 220.23 kWh
4010-Jul-2022 219.05 kWh
4105-Oct-2022 218.64 kWh
4228-Aug-2022 217.11 kWh
4308-Apr-2023 216.39 kWh
4409-Oct-2022 216.04 kWh
4502-Jun-2023 215.83 kWh
4612-May-2023 214.84 kWh
4715-Jul-2022 214.67 kWh
4809-Sep-2022 213.73 kWh
4915-Sep-2022 211.16 kWh
5003-Jun-2023 210.87 kWh
5120-Jul-2022 210.39 kWh
5214-Jul-2022 209.95 kWh
5318-Feb-2023 209.39 kWh
5423-Aug-2022 208.85 kWh
5510-May-2023 208.33 kWh
5623-Sep-2022 208.21 kWh
5711-Jul-2022 207.75 kWh
5823-May-2023 207.68 kWh
5909-Mar-2023 207.54 kWh
6020-Sep-2022 207.40 kWh
6121-Apr-2023 207.37 kWh
6219-Jul-2022 206.73 kWh
6321-Mar-2023 205.98 kWh
6411-Oct-2022 205.90 kWh
6524-May-2023 205.55 kWh
6612-Jul-2022 202.76 kWh
6707-Jun-2023 202.24 kWh
6814-Apr-2023 202.00 kWh
6915-Oct-2022 201.62 kWh
7020-Aug-2022 199.22 kWh
7105-Jun-2023 198.98 kWh
7221-Oct-2022 198.40 kWh
7322-Jul-2022 197.03 kWh
7425-Apr-2023 196.47 kWh
7516-Mar-2023 195.15 kWh
7611-Aug-2022 195.02 kWh
7705-Mar-2023 194.88 kWh
7823-Oct-2022 194.35 kWh
7913-Aug-2022 194.33 kWh
8031-Aug-2022 194.05 kWh
8127-Aug-2022 193.99 kWh
8213-Feb-2023 193.80 kWh
8301-Mar-2023 193.49 kWh
8424-Oct-2022 193.37 kWh
8522-Oct-2022 192.55 kWh
8629-Oct-2022 192.46 kWh
8725-Jul-2022 191.49 kWh
8813-Jul-2022 191.02 kWh
8926-Feb-2023 187.16 kWh
9011-Feb-2023 186.88 kWh
9102-Sep-2022 185.11 kWh
9216-May-2023 183.64 kWh
9326-Apr-2023 183.57 kWh
9425-Aug-2022 182.28 kWh
9510-Oct-2022 182.13 kWh
9606-Jun-2023 181.65 kWh
9708-Nov-2022 181.45 kWh
9817-Aug-2022 181.29 kWh
9901-Feb-2023 181.10 kWh
10024-Jul-2022 180.59 kWh