| Disaggregation of Revenue | 
The following table further disaggregates our revenue by major source by segment for the three and nine months ended September 30, 2019 and 2018.
 
|  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  
| Three Months Ended | September 30, 2019 |  
|   | Products and Services |   | Energy Production |   | Total |  
| Products | $ | 3,790,291 | 
 |   | $ | — | 
 |   | $ | 3,790,291 | 
 |  
| Installation services | 1,794,649 | 
 |   | — | 
 |   | 1,794,649 | 
 |  
| Maintenance services | 2,453,935 | 
 |   | — | 
 |   | 2,453,935 | 
 |  
| Energy production | — | 
 |   | 631,602 | 
 |   | 631,602 | 
 |  
|     Total revenue | $ | 8,038,875 | 
 |   | $ | 631,602 | 
 |   | $ | 8,670,477 | 
 | 
 
|  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  
| Nine Months Ended | September 30, 2019 |  
|   | Products and Services |   | Energy Production |   | Total |  
| Products | $ | 9,260,265 | 
 |   | $ | — | 
 |   | $ | 9,260,265 | 
 |  
| Installation services | 5,641,540 | 
 |   | — | 
 |   | 5,641,540 | 
 |  
| Maintenance services | 7,361,989 | 
 |   | — | 
 |   | 7,361,989 | 
 |  
| Energy production | — | 
 |   | 2,450,710 | 
 |   | 2,450,710 | 
 |  
|     Total revenue | $ | 22,263,794 | 
 |   | $ | 2,450,710 | 
 |   | $ | 24,714,504 | 
 | 
|  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  
| Three Months Ended | September 30, 2018 |  
|   | Products and Services |   | Energy Production |   | Total |  
| Products | $ | 2,765,094 | 
 |   | $ | — | 
 |   | $ | 2,765,094 | 
 |  
| Installation services | 1,648,119 | 
 |   | — | 
 |   | 1,648,119 | 
 |  
| Maintenance services | 2,065,651 | 
 |   | — | 
 |   | 2,065,651 | 
 |  
| Energy production |   |   | 1,459,820 | 
 |   | 1,459,820 | 
 |  
|     Total revenue | $ | 6,478,864 | 
 |   | $ | 1,459,820 | 
 |   | $ | 7,938,684 | 
 | 
 
|  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  
| Nine Months Ended | September 30, 2018 |  
|   |   |   |   |   |   |  
| Products | $ | 8,922,257 | 
 |   | $ | — | 
 |   | $ | 8,922,257 | 
 |  
| Installation services | 6,350,379 | 
 |   | — | 
 |   | 6,350,379 | 
 |  
| Maintenance services | 6,544,060 | 
 |   | — | 
 |   | 6,544,060 | 
 |  
| Energy production |   |   | 4,750,580 | 
 |   | 4,750,580 | 
 |  
|     Total revenue | $ | 21,816,696 | 
 |   | $ | 4,750,580 | 
 |   | $ | 26,567,276 | 
 |  |