Help for using the Virtual Solar Engineer

First let's take a look at the table example below. In order to determine how much a solar electric system will cost, you need to estimate your electrical requirements. You need to know or at least approximate how many watts each device uses. If you don't know how much power an appliance uses, click on the arrow on the list box above each table for average watts of common electrical appliances. If you will use the same size device (i.e.. lights, etc.)

In the example below we have two AC lights of 15 watts each (equal to 60 watt incandescent bulbs) that will be on for an estimated 4 hours each night.

We also have three twenty watt DC fluorescent lights (they run off the battery) that will be on for 4 hours a day and we fill in the appropriate boxes as given in the example below.

After using the load calculators, the totals will appear in the total adjusted load and TotalACDC watts boxes. If the totals are not there, click the calculate button at the bottom and continue. If you already know the adjusted load you may enter it in the adjusted load box and forget about the load calculators.

Click on the choose location link and from the world map that will pop up, choose the location where the PV system will be located. You then need to pick a module size - pick the largest one you think will do if you want the best value. You need to pick a system voltage and how many days of storage you require. A rule of thumb for days of storage is 9 minus the number that the map gives you for your location. I.e.. If the location number is 5 pick 4 days of storage, if the location number is 3 pick 6 days of storage. Next pick a battery size - the smaller amp hour battery will give you the best short term value and the larger battery will generally last longer. Most people use the smaller battery - the larger battery weighs 120 lbs, the smaller 62 lbs.

If the system is DC only click the calculate button, it you want AC power you need to pick an inverter that is large enough to supply all the power you need at one time. For example if you use a microwave, toaster and hair dryer all at the same time you will need a minimum 2400 watt inverter, if you will only use one of these at a time a 1500 watt inverter will be OK. If you are in doubt, pick the next largest size. Now click the CalculateTotalCost button.

You can try various combinations of modules, system voltages and battery sizes and see how it affects systems cost. Remember to click the Calculate button any time you make a change. Please understand that these calculators are only for roughly sizing a PV system and giving you an approximate cost. It is not a quote and prices may not be current.

The submit button will submit the form to us for review. We will evaluate your system and make recommendations that we may feel are necessary. Click on the reset button to erase all entries in all the calculators and start over.

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