TBARC Programs Solar Panel. 15 Aug 2013 By Israel AD7ND

Transcription

1 TBARC Programs Solar Panel 15 Aug 2013 By Israel AD7ND

2 Goal and Disclaimer The goal of this presentation is to provide basic information about solar panel systems which might help you understand some general concepts It is not intended to provide technical advice nor recommendations/suggestions nor does it favor any product, method or procedure mentioned in these slides; it is meant for educational purposes only

3 Credits All credits are given to the original authors for their articles, web-links or images, whether mentioned or not This presentation is also based on the following QST magazine articles: The Sun Shines on the Granite Bay Montessori Shack - Feb 2011 An Emergency Backup Solar Power System - May 2011 Build an AH Meter for Portable Operations - May 2010 A Solar Powered Repeater for EmComm - Sep 2010

4 Topics Background Information Batteries Charge Controllers Basic Experiment Power/Energy Budget Determine Battery Capacity Calculate Solar Panel Capacity Choosing a Charger Controller Solar Panel Orientation and more

5 We would like this one

6 Basic Components Solar Panel Battery Controller Load Solar Panel Charge Control Battery Load Solar Panel = Photovoltaic Panel (PV)

7 What are PV Cells? Photovoltaic = direct conversion of light into electricity at the atomic level Photoelectric materials absorb photons of light and release electrons It is a P-N junction

8 PV Cells Regardless of size, a cell produces about Volts DC (open-circuit) Cell current depends on size, efficiency and sunlight intensity A typical PV cell with a surface area ~25 in 2 produces ~ 2 Wpeak

9 Types of PV Cells Three types of Cells: Monocrystalline (~15%) Polycrystalline (~12%) Thin Film (~6%) Monocrystalline Polycrystalline Thin Film

10 Solar Panel Specs Manufacturer Specs: Standard Test Conditions (STC): 1,000 W per m 2 Irradiance 25 C (77 F) Cell Temperature 1.5 Air Mass Index

11 Solar Panel Specs A a b V K ZL K = Open ab = Open Vab = VOC VOC = Open Circuit Voltage A a b V K ZL K = Open A = ISC ab = Short ISC = Short Circuit Current

12 Current-Voltage and Fill Factor I-V curve shows Isc and Voc for a particular panel Max Power Fill Factor parameter, together with Voc and Isc, determines the Max Power from a solar cell

13 Solar Panel Facts Power on label is at peak rating and not realistic; it s under ideal conditions (Standard Test Conditions) A solar panel only produces its rated power at high noon on the Equator on Mar 22 and on Sep 23; if the panel temp is 25 C -- you will never see that condition in real world Solar Insolation is measured in Kw-hs/m 2 per Day, which is called "Sun Hours / Day

14 PWM Charger Controller Basic Voltage and/or Current regulator to keep batteries from overcharging Regulates Voltage and Current coming from the Solar Panels to the Battery Without regulation the Battery will be damaged when charged above voltage limit Needs around 14 to 14.5 Volts to get fully charged

15 MPPT Charge Controller - How it works Continuously monitors the Solar Panel output power while changing the load by a small amount Controller keeps changing the load until Power no longer increases, that s MPP

16 Simple Charger Controller Possibly good for up to 5 Amps.

17 Test Setup PV Volts Charge Control Battery Volts Power Meter Battery Stop Watch For Battery Charge and Discharge Measurements

18 Battery - Charge/Discharge Charging Battery Solar Panel charging Battery Discharging Battery In Controller Out Load charging Battery Solar Panel Battery Load Power Meter

19 Equipment Used Equip Spec/Brand Remarks Solar Panel Monocrystal 36 cells 25W / 1.5 Amp Charge Regulator TW Amp Battery-1 ES5LBS ~ 4 Amp/hr Battery-2 U1R CA ~ 22 Amp/hr Power Meter SkyRC A, V, W, Ah, Wh Digital Meter Cen-Tech Volt monitoring Cronograph Ultratek Time Charge/Disch Load-1 Load-2 12V 28W Bulb 12V 15W Bulb

20 Lead Acid Batteries Basically there are 2 main types of Lead Acid Batteries Starting (cranking) Deep Cycle Starting Battery (aka SLI = Starting-Lights-Ignition) is designed to deliver quick bursts of energy (starting engines) and therefore has a greater plate count -- thinner plates and different material composition Deep Cycle Battery has less instant energy, but greater long-term energy delivery -- has thicker plates and allows for more discharge cycles

21 Types of Lead Acid Batteries Cells Wet Cell (flooded), Gel Cell, and AGM (Absorbed Glass Mat) are versions of the lead acid battery Gel Cell and AGM batteries typically cost 2X as much as a premium wet cell The trade-off in battery development is that they can be either High-Power or High-Energy or High- Durability, but these are mutually exclusive

22 Battery Ratings Amp-Hr (Amperage-Hour) RC (Reserve Capacity) CCA (Cold Cranking at 0F/30s) CA (Cranking Amps at 0F/30s) MCA (Marine Cranking at 32F/30s) HCA (Hot Cranking at 80F/30s) PHCA (Pulse HCA at 80F/5s) Amps delivered for 30 sec and maintain >= 1.2 volts per cell (7.2 V) Reserve capacity = Time (min) that a new, fully charged battery will deliver 25 Amp at 80F and maintain a Voltage >= 1.75 volts per cell (10.5 V)

23 Battery Amp-hour (Ah) Amp-hour rating tells you how much Amps can be available when the battery is evenly discharged over a 20 hour period Amp-hour rating is cumulative, so in order to know how many constant Amps a battery will output for 20 hours, you have to divide the Ah rating by for example: 75 Ah / 20h = 3.75 A A 75 Ah battery can provide a 3.75 A load for 20 hours before its voltage drops to 10.5 volts 10.5 volts is the fully discharged level, at which point the battery needs to be recharged +

24 Battery Voltages Charge (no load) Cell Battery Remarks 0% 1.75 V V 10% 1.89 V V 20% 1.93 V V 30% 1.96 V V Destructive discharge below 40%. 40% 1.98 V V 50% 2.03 V V Normal discharge limit 75% 2.06 V V 90% 2.08 V V 100% 2.12 V V Float charge: 2.18 V V Maximum voltage during charge: 2.40 V V

25 Volt and Amp Curves

26 Power and Capacity

27 W (Power) vs. Wh (Energy) Watts and Watt-hour are very different animals W is a measure of Power Wh is a measure of Energy Power = Energy Time Power is: a measure of how fast Energy is being converted (1W = 1J/sec) or the rate at which energy is being converted to another form of energy Energy is: a measure of how much fuel is contained within something or generated by something -- for example, 172 Calories = 0.2 Wh

28 Solar Panel Tilt Calculation In order to get the most out of Solar Panels, they need to be pointed in the direction that captures the most Sun In the Northern Hemisphere Solar panels should always face True South, and in the Southern Hemisphere True North Rule of thumb is: TILT WINTER = Lat + 15dgs TILT SUMMER = Lat 15dgs But it can get better than that: PHX Lat = 33 dgs Winter = 48 dgs Summer = 18 dgs

29 Other Solar Panel Tilt Calculator If you cannot change the angle of your panel throughout the year, angle your panel according to the time of year that you need to get the best performance out of your system n_position.html

30 Determine Power & Energy Budget 1. Find the average current drawn by each equipment: multiply current (Tx and Rx) by the (%) Duty Time then add them together to determine the Avg Current in Amps 2. To calculate Power (W) just multiply the Avg Current by the voltage 3. Calculate Amp-hours by multiplying the total Avg Current by the number of Hours the equipment is expected to be operated per day 4. To find the total watt-hours (Wh) multiply the Power by the daily hours using the radio. Calculate the Wh for each equipment

31 Power and Energy Budget

32 Determine Battery Capacity 5. This step determines the Battery Capacity required to run the station without being charged by the solar panel 6. Take the number of days necessary to run all the equipment without using solar panel (Sunless Days) and multiply it by the Amp-hour needed to run the station; the result is the required Battery Ah Capacity 7. Choose the nearest (high) Battery Capacity commercially available

33 Battery Capacity

34 Determine Solar Panel Power 8. To calculate the Solar Panel use the Energy budgeted in step 4 9. Take the Wh value and divide it by the Min number of Hours of Sunlight per day (winter is better); this results in the Min Solar Panel Wattage 10. Considering that Solar Panels only produce about 50% of their rated power in the real world, then multiply the Solar Panel Wattage by 2 in order to determine the Solar Panel Watts needed to run the station

35 Solar Panel Wattage

36 Price Comparison at Amazon Component Brand/Features Retail Coleman Monocrystalline 130W $615 Solar Panel Ramsond Monocrystalline 100W + Charger $237 HQRP Monocrystalline 50W $138 Instapark Monocrystalline 30W $89 TrakMax 40A 12/24 $219 MPPT Charge Controller MorningStar 60A 12/24V $190 SainSonic 2210RN 20A 12/24V $149 SainSonic 1215RN 10A 12/24V $96 PWM Charge Controller Ramsond SunShield 8A 12V $20 HQRP 10A 12/24V $32 Sunforce 7A 12V $17

37 References (Batteries) (LiFePO4 Batteries)

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