Efficiency is key
The income you receive from your solar photovoltaic installation is directly linked to its efficiency in terms of generating electricity from light and subsequently feeding this in to the electricity distribution network. Because several factors can affect productivity, effective operation and maintenance is key to protecting your investment.
The two major components of this productivity are the ease with which light reaches the semiconductor surface beneath the protective glass on a panel, and the efficiency with which the inverters deliver electricity in AC form to the network. In the first case, regular panel cleaning will ensure that the maximum amount of light reaches the active surface of the panel. The second is more complex, with numerous potential risks to consider.
Since the Feed-in Tariff is paid over a fixed term, revenue lost through reduced productivity can not be recouped later. The longer it takes before it is rectified the more revenue will have been lost.
NWT Energy offer operation and maintenance services for commercial scale solar photovoltaic installations. We can inspect your system and provide you with a condition report that will allow you to decide whether you wish to take any action. You can see examples of some issues we have identified in the “Our Projects” section.
Sample of inspections
Following numerous requests from property professionals for solar PV Operation and Maintenance services, here we have summarised initial findings from a sample of 20 in order to illustrate the common themes.
||PREVIOUS MAINTENANCE DATE||PV SYSTEM SIZE (kW)||NUMBER OF INVERTERS||SOLAR ARRAY(S) OK||INVERTER(S) OPERATIONAL?||MONITORING IN PLACE?||ELECTRICAL CONNECTIONS OK?||CLEANING REQUIRED?||CONDITION||FIRMWARE UP TO DATE?||WARRANTY REMAINING|
|NWT REF||SITE LOCATION|
|1003||OXFORDSHIRE||Q2 2014||100||4||✔||✖||✖||✔||ADVISABLE||POOR||✖||3 YEARS|
|1004||HERTFORDSHIRE||Q1 2014||190||7||✔||✔||✔||✔||ADVISABLE||GOOD||✔||3 YEARS|
|1005||KENT||Q4 2012||50||2||✔||✖||✖||✔||URGENT||FAIR||✖||1 YEAR|
|1006||EAST SUSSEX||Q4 2013||30||1||✔||✖||✔||✖||ADVISABLE||FAIR||✖||2 YEARS|
|1013||NORFOLK||Q2 2014||150||6||✔||✖||✔||✔||ADVISABLE||FAIR||✖||3 YEARS|
|1014||KENT||Q2 2013||30||1||✔||✖||✖||✔||ADVISABLE||GOOD||✖||2 YEARS|
|1016||EAST SUSSEX||N/A||50||2||✔||✔||✖||✔||ADVISABLE||GOOD||✔||3 YEARS|
|1018||EAST SUSSEX||N/A||50||2||✔||✔||✔||✔||OPTIONAL||GOOD||✔||3 YEARS|
Generally speaking, NWT’s engineers have been struck by the lack of effective handover processes in almost all instances. This, coupled with an almost total absence of practical monitoring equipment, has led to situations where avoidable losses are frequent and more serious equipment issues are not addressed in good time. In addition:
- Only 5 of the 20 sites had any monitoring apparatus at all. We consider this equipment to be an essential component of any solar PV system.
- A quite alarming 9 of the 20 sites had one or more inverters not operational at the time of our visit. Often these have been faulty for several months, and at one site this appears to have been the case for over a year.
- A key area of concern is that only one of the sites we attended had a clearly visible broken array, and in 17 of the 20 sites cosmetic appearance has been classed as “Fair” or “Good”. This masks the true condition of the electrical side of the system.
- In most cases the amount of dirt build up was broadly as expected, however there were some older systems where lichen had been able to grow on the surface and bird droppings had reached the point where they were causing significant losses in generation. Once lichen is established the cleaning process takes far longer to complete.
Aside from inverter failure, the most concerning aspect of the surveys was the almost total absence of effective monitoring systems. Without having a suitable method for identifying issues with the system it is impossible to know whether it is operating as it is intended to. We were surprised and troubled by the number of systems that contained no monitoring apparatus. In many cases substantial revenue had been lost because the owners were not aware of underlying issues with their PV systems.
The length of warranties varies substantially between manufacturers, as does their reliability. In several instances during our study the warranties were no longer being honoured by the companies that manufactured the components or the companies were out of business. Where we were able to make warranty claims these tended to be dealt with fairly rapidly. In one case we discovered 8 separate inverters that were all marginally out of warranty, even though the failure was likely to have happened much earlier. An effective monitoring system would have identified this and saved the owner several thousand pounds in replacement costs.