EGR100- Engineering Seminar Going Solar in the Park

EGR100- Engineering Seminar Going Solar in the Park The town park committee is planning a new picnic shelter and desires for it to be powered by solar energy if possible. You have been commissioned to present the case to council if it is feasible to use totally solar electricity to power the shelter.

EGR100- Engineering Seminar Where do you begin? List the potential electric demands of the shelter and how long these needs will last. For example: General lighting: 200 watts for a maximum of 5 hours – park closed at 11pm and it is usually light until 7 when it is warm enough for the shelter to be used. Can you think of some other uses at the shelter?

EGR100- Engineering Seminar Estimated Use in Shelter ItemWattsTime(hr)WHR Lighting Coffee Pot Sound System Warming tray Other Total

EGR100- Engineering Seminar zOn your web site is a program called “Solar Budget”. Download this to your Desktop and run. What is the solar budget for your home?

EGR100- Engineering Seminar Need System to provide 4300 WHr of energy during darkness or light to meet potential usage. Critical time is the dark hours. During daylight sun will generate enough power for the shelter. To operate after dark batteries will be needed. During daylight the 200 W load for lighting will go to charge the batteries. This yields 2400 Whr of energy. We need to supplement this with an additional 2400 WHr of charging energy during the estimated 12 hour of daylight.

EGR100- Engineering Seminar This would mean we need a total of 6300 WHr for a busy day- both day and evening bookings of the shelter. So we want 2600 W possible.

EGR100- Engineering Seminar This is a typical set of battery specs. We will use 6 volt batteries and use series/parallel connection.

EGR100- Engineering Seminar Typical “deep-cycle” batteries will offer 490 minutes of discharge at 25 Amps. This should be sufficient. We will make a bank of twenty four 6V batteries in series/parallel for a 12 volt system. At about $343/battery, this is $8,232 dollars for the system.

EGR100- Engineering Seminar How many panels will be needed?? The Solar Calculator will figure that for us based of the specs for a specific panel. The picture shows an installation of 24 Siemens panels

EGR100- Engineering Seminar

The remaining item needed is the charging and 120 volt inverter system. A battery charger controller is about $750 based on Internet searches and the DC to AC inverter to output up to 25 Amps is $1,900. These panels (Siemens SP75) sell for $346 each. For 23 panels we need $8, W Inverter

EGR100- Engineering Seminar The Estimated Parts Cost will be: ItemCost Estimate Solar Panels $8,958 Controller $ Inverter $1, Batteries $ 8, Total $19,840.00

EGR100- Engineering Seminar To this would be added 25% for mounting parts, wiring etc and 25% for labor so the total system should run about $29,760 This will be within a reasonable budget for the park department project. Now How to write this to present to the Park Department Committee. We will use the engineering paper for this report.

Solar in the Park1/4 A Engineer 1/05/2009 Problem: Givens: Solution: The town park committee is planning a new picnic shelter and desires for it to be powered by solar energy. This paper determines if it is feasible to use totally solar electricity to power the shelter. Park Closes at 11:00 PM Lighting to be available for only 5 hours Maximum. Power Outlets to be both fused and timed for conservation. Reservations for use will be 10 am to 4 pm and 5 pm to 11 pm. It is necessary to determine the estimated load that must be supported. The table below displays that estimate.

Solar in the Park2/4 A Engineer 1/05/2009 ItemWattsTime(hr)WHR Lighting Coffee Pot Sound System Warming tray Other Total The Rating of WHr is the total energy that must be available in the battery bank. The 2400 W rating relates to the peak power that must be available at any point in time. This figure dictates the size of the solar panel and the size of DC-AC converter needed. During the Day we need 200 Watts less which will lead to 2400 WHr of energy that can do to the batteries. However, this leaves 1900 WHr short for evening use. We recommend 6300 WHr as our target value.

Solar in the Park3/4 A Engineer 1/05/2009 One manufacturers panel that is typical would suggest we need 23 panels using the Siemens SP75 to reach the necessary power level. Of course, we would submit the project to competitive bid to obtain the best price. Additional items needed will be a battery bank, charger/controller and an inverter to change 12 V DC to 120 V AC. Using a variety of Internet sites for solar panels yields the estimate below

Solar in the Park4/4 A Engineer 1/05/2009 ItemCost Estimate Solar Panels $8, Controller $ Inverter $1, Batteries $ 8, Total $19, Add to this 25% for mounting hardware, wire, etc., and 25% for labor and we have a project at $29,760. Recommendation: This is a reasonable expense we would have no connection to the power company. Estimated life time is 20+ years with reasonable maintenance. Factors not researched but important are: possible grant support for Green Installations, potential to sell power back to the power company, and the political good will at producing a Green Project.

EGR100- Engineering Seminar If you wish to pursue this topic further, use google to search fro solar panels or solar electric design. The other term to search is PV design for photovoltaic. Also there is a solar load calculator on our lesson page. You can download it and play with these and your own numbers. This is a “HOT” topic right now as a means to lower our dependence on oil and to lower individual and corporate energy costs with out giving up usage. Dr. Cunningham, 2009

EGR100-Engineering Seminar Although you will not be a wizard, when you present yourself professionally, and with clarity, others may think you a wizard! At promotion time that will not be a bad thing.