M. STOEV Small Energy Save PV Systems

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Small Energy Save PV Systems

M. Stoev

Solar Energy Centre

Faculty of Mathematics and Natural Sciences

South-West University “Neofit Rilski”

Blagoevgrad, BULGARIA

Website: www.swu.bg

E-mail: [email protected]

http://www.swu.bg/

http://www.swu.bg/



Agenda

• Energy mix

• BIPV

• Energy safe micro solar systems

• PV modules• Micro-inverters

• Small Grid Tie Photovoltaic System (SGPV)



Energy mix in Bulgaria

• Outdoor energy mix

http://www.tso.bg/default.aspx/page-

707/bg

• Indoor energy mix

http://www.tso.bg/default.aspx/page-707/bg







Energy mix in Bulgaria,

5th January, 2015





PV systems

• PV plants: land, construction, long

distance transmission grid, high

investment costs, losses

• Small Energy Save PV Systems: BIPV

(near production, local consumption)



BIPV: Residential Solar System Designs



Energy safe micro solar systemshttp://microsolar.sts.bg/



Micro solar system 250 Wp

PV module: Bosch Solar c-Si M 60 - 235W

Micro inverter: AE Conversion INV 250-45

Micro computer: LongiLight Premim

Construction: Visor façade

Price: 700 Euro



Bosch Solar c-Si M 60 - 235W

• Pmax = 235 W

• Uoc = 36.60 V ; Isc =8.40 A U mp = 30.00 V; I mp = 7.85 A

• η = 14,61 %; P tolerance = +/-3%; Temperature coefficient Isc = + 0.039%/o K

• Temperature coefficient Uoc = - 0.360%/o K; Temperature coefficient Pmp =

- 0.500%/o K; Temperature diapason = from - 40 oC to + 85 oC



Micro-inverter











72-cell PV module













Micro-inverter benefits

• Individual Optimization

“Shading of as little as 9% of a solar system connected to a centralinverter, can lead to a system-wide decline in power output with asmuch as 54%”

• MPPT• Longer Warranty: 20 – 25 Years

• Easily Expandable

• Performance Reports

• No single point of Failure• Improved Safety

• Silent



Energy safe micro solar systems



Grid tie inverters



Dual micro-inverters

• 2011

• Two PV panels and one dual micro-

inverter











Specific applications of micro-inverters

• Shading

• Difficult roof orientations

• Starter systems• Small applications







Grid tie inverter 500 W





Advantages of SGPV

• Low cost and easy installation

• Free combination

• Combination of SGPV does not interact• Improving the efficiency of the entire solar

power system

• Low power consumption



Grid tie inverter

• The power of grid tie inverter should be

matched to the power of solar panels connected.

• The inverter can be connected to any outlet athome, when this line run by the conventional

electric network.

• pure sine wave

• frequency and phase are as same as the grid's

• Island Protection



Electrical specifications of Grid tie inverter 500 W

• Maximum AC Output Power: 500 W• AC Output Voltage: 190V ~ 260V

• AC Output Frequency Range: 46Hz ~ 65Hz

• Total Harmonic Distortion(THD) <5%

• Power Factor: 0.99

• DC Input Voltage Range: 24V ~ 52V • Peak Inverter Efficiency: 92%

• Standby Power consumption: <0.5W

• Output Current Waveform: Pure Sine-wave

• MPPT Function: YES

• Over Current Protection: YES

• Over Temperature Protection: YES

• Reverse Polarity Protection: YES

• Island Protection: YES

• Stackable: YES



Power factor

• Low power factor (PF) presents a heavier generationand transmission burden on the power grid and alsodeposits a larger carbon footprint.

• Real power [kW]: heating and lighting

- supply voltage and load current are "in-phase"

• Reactive power [kVar]: loads with inductive andcapacitive elements (motors, lamp ballasts)

- supply voltage and load current are 90-degrees out-ofphase with each other

• Apparent power [kVA]: vector sum of real and reactivepower

- total burden placed on the grid by the load from both itsreal and reactive parts



Power factor

• A lagging power factor is associated with an inductiveload, while a leading one is indicative of a capacitiveload

• True power factor is then a combination of simplephase displacement and harmonic distortion

• The inefficiencies associated with low power factorrequire larger power plants and bigger transmission linesto generate and deliver the higher currents.

• GTIs are designed to operate with a unity powerfactor output and be synchronized with grid

frequency.• GTI does not contribute any reactive kVar production

to the equation, which leaves the utility to bear theentire burden



Power factor

Utility power factor with grid-tie inverter (GTI)

Relationship between real, reactive and apparent power

Utility power factor without grid-tie inverter (GTI





Micro inverter: AE Conversion INV 250-45

• DC• P max inp = 250 W; U max inp = 45 V; U min inp = 18 V; I max inp = 11 A

• AC

• P max out = 250 W; I nom = 1 A; U nom = 230 V; H nom = 50 Hz;

P factor >0.99 Cosφ, Temperature diapason = from - 25 oC to + 70 oC



LogiLight Premium

• U nom = 230 V; I max = 16 A, H nom = 50 Hz; U tolerance = 175…275 V;

Temperature diapason +5…+ 85 oC

Measure: U [V]; I [A]; H [Hz]; P [W], E [kWh]; Cosφ





SGPV South-West University, BG

May, 2014



SGPV South-West University, BG

November, 2014



SGPV Karaganda State University, KZ

-25 oC, December, 2014





Thank you for your attention!

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M. STOEV Small Energy Save PV Systems