Maintenance services

Inspection & condition report

Solar PV standards vary widely across the UK, with many systems hastily installed during intensely busy periods leading up to various Feed-in Tariff reductions. Even relatively minor faults within PV systems can significantly reduce their output and lead to a substantial loss of income. NWT Energy can inspect the electrical connections and inverter condition at your site, providing you with a condition report. We can also perform a visual inspection of the array without the need for scaffolding or access equipment, using our drones.

Inspection & condition report

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.

Solar Edge inverters

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.

Cleaning Image 5

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
1002 NORFOLK N/A 150 6 ADVISABLE FAIR 3 YEARS
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
1007 ESSEX N/A 40 2 ADVISABLE GOOD 3 YEARS
1008 LINCOLNSHIRE N/A 50 2 ADVISABLE GOOD 2 YEARS
1009 LINCOLNSHIRE N/A 50 2 ADVISABLE GOOD 3 YEARS
1010 NORFOLK Q1   2011 350 54 ADVISABLE GOOD NONE
1011 ESSEX N/A 39 2 OPTIONAL GOOD 4 YEARS
1012 ESSEX N/A 50 2 OPTIONAL GOOD 4 YEARS
1013 NORFOLK Q2   2014 150 6 ADVISABLE FAIR 3 YEARS
1014 KENT Q2   2013 30 1 ADVISABLE GOOD 2 YEARS
1015 NORFOLK N/A 150 6 ADVISABLE FAIR 3 YEARS
1016 EAST SUSSEX N/A 50 2 ADVISABLE GOOD 3 YEARS
1017 SUFFOLK N/A 250 10 OPTIONAL POOR 3 YEARS
1018 EAST SUSSEX N/A 50 2 OPTIONAL GOOD 3 YEARS
1019 CAMBRIDGESHIRE N/A 50 2 ADVISABLE GOOD 3 YEARS
1020 HERTFORDSHIRE N/A 95 4 ADVISABLE POOR NONE
1021 ESSEX N/A 30 1 ADVISABLE GOOD 2 YEARS

General findings

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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.

Remedial Work example

Monitoring

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.

 

Warranty term

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.