Export Limiting in Practice

Transcription

1 Limiting in Practice James Hoare CEng MIET MEI BRE National Solar Centre -Associate Consultant LHW Partnership LLP - Partner 24th September 2014 Part of the BRE Trust

2 Limiting in Practice Grid Background Evolution Renewable & PV Development A Fictitious Application Example A Real Life Example Q&A

3 The UK Grid - Background Pre 1926 Decentralised System with local generating supply companies 1926 CEGB established with a Nationwide synchronised 132kV network kV Network established based around centralised power stations and decentralised demand customers Statistics at Privatisation in ,500 km 400 kv circuit, 9,800 km 275kV Circuit, 5250 km 132kV circuit. Essentially 1 GenCo (nearly no IPPs) 12 Regional Electricity companies Purpose with a centralised energy policy to get energy from Generators Consumers

4 The UK Grid 1989 The Electricity Act paved way for Privatisation in CEGB (Central Electricity Generating Board) broken up into National Grid (Transmission) & Powergen, National Power, Nuclear Electric with NGC controlling the Pumped Storage (principally Dinorwig / Ffestiniog) asset for emergency demand balancing. 12 Regional electricity Companies (now 6 DNOs) distributing from 132kV to 33/11 & LV customers. To that point both the transmission & distribution networks had ben designed and evolved for centralised and not local power generation

5 The UK Grid As part of 1989 Electricity Act introduced the NFFO (Non Fossil Fuel Obligation) a precursor to the RO (Renewables Obligation). The first tranche was October 1990 with a number of projects mainly Wind, Landfill Gas, Straw/Poultry litter & Hydro. (No PV) Local Cornwall projects were mainly wind Delabole Goonhilly Carland Cross St Breock Connecting these to the distribution network was uncomplicated, as though the network was designed for consumers, (not prosumers), the relative impact was minor, and plenty of generation capacity.

6 What is a Prosumer? A Prosumer is a term evolving in Europe to define an entity (domestic, commercial, public sector) that Produces energy & consumes Energy

7 The UK PV Industry First Grid tied PV System(s) were connected in 1994

8 The UK PV Industry year 2000 Total PV Connected Capacity c1mwp No FIT s or ROC s (nor in Germany) A large project was typically 12kWp G83 not in existence Largest UK PV programme at the time BP Solar Project Sunflower a 1098 kwp programme covering canopies on 76 UK petrol stations from 1996 to 2002

9 The UK PV Industry year 2015 Total PV Connected Capacity April 2015 c8gwp (8000 MWp) Circa 700,000 DNO grid connected Installations A large project is now MWp At peak PV output in July 2015 a sunny weekend day will meet c15% of UK early PM national demand (UK demand data - source gridwatch.templar.co.uk)

10 The UK PV Industry year 2015 The move from Centralised to Decentralised (prosumer) power generation, and the rapid growth of the Renewable market, has started to put pressure on the Distribution network that is evolving from consumer based demand system to a prosumer system. Consequently there are now network constraints on connecting DG

11 What is Network & Constraint? When the potential amount of locally generated electricity has reached a level when the DNO cannot accept any more without breaching its Licence conditions & ESQCR a constraint may be needed The solutions are impose an export constraint to limit the export of energy Upgrade the network to accommodate the requirement Currently The Electricity Regulator Ofgem s regulations means that the cost of network reinforcement for Distributed Generation Projects should be paid for by generator and not bill paying customers (DUOS). The DNO s have to enforce this.

12 ESQCR Electricity Safety Quality & Continuity Regulations Principal Stakeholders Reportable by Members of public, Meter operators, distribution and transmission companies, generators and suppliers Key aspect in context The DNO is licenced and legally bound to provide phase voltage to customers at 230V +/- 10% (ie between 207 & 253V) Demand Customers reduce voltage with increased demands, Prosumers can raise grid voltage with increased generation (G83/2 is 262V to allow 3% volts rise between DNO connection and

13 White Goods are built to work within ESQCR limits For European Harmonisation all electrical appliance are designed to work between 207 & 253V

14 White Goods are built to work within ESQCR limits For European Harmonisation all electrical appliance are designed to work between 207 & 253V A DNO can be prosecuted if for example was found to be caused by providing to a voltage outside ESQCR regulations

15 When is Limiting Network Reinforcement Required? The DNO may propose an export constraint or network reinforcement for 2 principal Reasons when you apply to connect a PV (or other DG system) 1. The voltage rise may put the network out of ESQRC compliance 2. The thermal capacity of the network has been reached If the network fault level has been reached, export constraint will not resolve the issue.

16 A Fictitious Worked Example to demonstrate the impact of export constraint, and options of how to manage the impact

17 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell

18 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell Assumed Annual Electricity Consumption c50,000 kwh Initial idea Install a 50kWp array to match annual consumption with a combination of onside consumption with some export

19 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell System Size 50 kwp System Annual generation 47,000 kwh Estimated On Site use 50% 50% Revenue from FITs,, Import offset Decent ROI & IRR To Proceed with project - No Planning needed, just DNO approval..

20 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell ENA Connection Application sent to DNO for 50kVA PV connection A few days later the DNO responds outlining You can connect a system to export 50kW Due to the level of existing DG connections in the area, network network upgrade costs in the order of 500,000 will be required, or you can connect a system that can export 20kW (KVA) with no additional reinforcement needed. NB Figures Entirely fictitious and fabricated

21 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell What do you do?

22 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell What do you do?

23 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell But what do you do?

24 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell The 2 key things you need to assimilate are 1. Relationship between kwp and real time kw system yield quantum. 1. On Site Energy Demand profile (if any) In context of ed Energy = Generated energy onsite demand

25 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell Generation Do annual / monthly yield and other such models help when there is an export constraint? Yes a bit, but in reality not very much

26 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell Generation

27 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell Generation PV Syst can output modeled Hourly generation data sets in CSV/Excel

28 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell Key Graph derived from PVSyst Hourly Generation

29 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell Key Graph derived from PVSyst Hourly Generation Mean operating output 11kW Max output 50kW Area under line Hours x % of max 50 kw = total kwh

30 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell Key Graph derived from PVSyst Findings PV System will be generating for 47% of year Max output is 50kW Average operating generation output is 11 kw (22%) (This is not generic and is project / location specific)

31 Fictitious Case Study 50 kwp Rooftop The Eden Project Offices, St Austell 20 kw limit total export Annual Hours of Unconstrained Outputs as a Percentage of Max 50kW Output Point for the example 50 kwp System where a 20kW export constraint will need to limit the outputs to keep within Unconstrained Output 20kW export 5 Periode gleit. Mittelw. (Unconstrained Output) Hours of Operation 250

32 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh none 0 100%

33 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh none 0 100%

34 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh none 0 100%

35 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 49kW %

36 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 48kW %

37 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 47kW %

38 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 46kW %

39 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 45kW

40 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 44kW %

41 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 43kW %

42 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 42kW %

43 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 41kW %

44 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 40kW %

45 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 39kW %

46 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 38kW %

47 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 37kW %

48 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 36kW %

49 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 35kW %

50 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 34kW %

51 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 33kW %

52 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 32kW %

53 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 31kW %

54 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 30kW %

55 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 29kW %

56 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 28kW %

57 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 27kW %

58 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 26kW %

59 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 25kW %

60 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 24kW %

61 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 23kW %

62 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 22kW %

63 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 21kW %

64 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 20kW %

65 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 20kW %

66 Conclusions from Model 84% of max yield in Cornwall with a 20kW export constraint on a 50kWp system is still probably higher than yields in North of England with no constraint There are lots of variables, so allowing sensitivity and contingency are important.

67 Model With on site Energy Demand 50kWp Array 20kW export Constraint On site Consumption

68 If Site Demand is added to the 50kwp system with an export constraint of 20kW max Assumption for model 5kW continuous at weekends (Sat & Sunday) Weekday model graded in incremental steps of 5kW (Historic HH consumption data is desirable if available) January sample HH Consumption Data

69 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 20kW 0kW 84.0% 0kW

70 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 20kW 0kW 84.0% 0kW

71 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 20kW 5kW 5kW 88.1%

72 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 20kW 10kW 5kW 90.5%

73 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 20kW 15kW 5kW 92.5%

74 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 20kW 20kW 5kW 94%

75 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 20kW 25kW 5kW 95.1%

76 Max PV Gen Constraint On Site Demand (5d/weekend) % of Max 47 MWh 20kW 30kW 5kW 95.9%

77 Key Factors A Degree of sensitivity / contingency is required as both solar radiation and on site demands are intermittent and will vary year on year PVSyst estimates hourly outputs in kwh, so need to be careful when matching to on site demand as 1 kw for one hour = 1kWh (as does 0.5 kw for half an hour and 1.5KW for half an hour) Sensitivity needed The more consumption information the better Half hourly data, and a thorough energy consumption profile is helpful. (The more demand info the better)

78 Conclusions from Modeling The impact of network constraints is probably less than anticipated, and a larger array than anticipated may be possible. Choose a conservative and least optimistic solar dataset. Maybe use P90 irradiance data If you are modeling with historic Half Hourly consumption data remember this is historic and not assured year on year Allow contingency, and be cautious with energy yield projections the level of yield risk is higher than total export. If in doubt Ask BRE NSC for modeling assistance!

79 Limiting Case Study a 1.2 MWp Zero Rooftop Vegetable Storage Cambridgeshire 2013

80 Limiting Case Study a 1.2 MWp Zero Rooftop Vegetable Storage Cambridgeshire 2013 Large provider of parsnips to supermarkets Large onsite energy use for refrigeration DNO could not allow any export due to large wind farm on same circuit

81 Limiting Case Study a 1.2 MWp Zero Rooftop Vegetable Storage Cambridgeshire Undertook Modeling of 2 years historic consumption data Modeling showed 1.2MWp would provide 95% of maximum projected generation output with zero export constraint. System installed DNO Witness test on G59 & export limiting system Learning experience solar gain reduction on roof reduced energy consumption by a few %

82 Limiting Case Study a 1.2 MWp Zero Rooftop Vegetable Storage Cambridgeshire Commissioned March MWp 4,400 PV Modules 9 x 100 kw Inverters G59/2 Switchgear PLC based sensing Actuator & Controls

83 Limiting Case Study a 1.2 MWp Zero Rooftop Vegetable Storage Cambridgeshire Subsequent application to DNO for variable export allowance successful Site can export 97% of time, so nearly 100% of projected yield is attainable Ultimately Active Networks will prevail

84 Thank You Any Questions?