Planning Your Electrical Budget

If you plan your electrical budget and daily use when you plan your home size, your land cost and home furnishings; you can have all your power needs met and by using more panels and a wind generator, you may not need to use your back up generator very often. That equates to less noise while you enjoy your pristine getaway home or cabin.

Now, how about batteries to store all this energy that the sun produces. Batteries come in lots of flavors, just like solar panels. 2 volt – 6 volt – 12 volt – 200 amp hours – 300 amp hours – 400 amp hours and so on.

Let’s use a 6 volt 210 amp hour deep cycle battery that is readily available from most suppliers. Since we had decided on a 24 volt system we will need 4 of these 6 volt batteries to make one 24 volt battery. This 24 volt battery still has the original 210 amp hours that the 6 volt battery had. We will however need to adjust this figure by the amount of discharge that we will allow. Typically this battery should only be allowed to discharge to 30% to 50% in order to get the longest life out of it. So, are you ready for another calculation? 210 amp hours minus 30% equals 63 amp hours. (210 x .3 = 63)

Now we need to change our watt hours to amp hours to find out how many batteries we will need for our daily use. We have 2,344 watt hours and to translate that into amp hours we need to divide that by the 24 volts and we determine that we have 98 amp hours used on a daily basis. (2,344 divided by 24 = 98; watts divided by volts = Amps)

Our panels which are 6 of the 120 Watt, 12 volt modules will produce 120 amp hours and that will be more than enough for our example which calculated out to be 98 amp hours as you will remember.

If each string of batteries (4 @ 6 volts) allows us 63 amp hr. then we need 2 strings or 8 batteries. 963 amp hour x 2 = 126 amp hours)

We have not factored in automony, wind generators or back up gas generators. However you can see some of the first general steps.

Please keep in mind that, sooner or later, you will have to get ‘techy’ if you plan to do it yourself. Sometimes it is better not to try to build your own car when there are professionals that can find out what your requirements are and deliver a product suited to your needs.

About the Author
Larry LeDue has been designing, installing, and servicing solar systems since 1990. He is an active/certified member/installer with COSEIA; and lives with his wife in an active and passive solar home they built in South Park, Colorado.

This article is the property of Sustainable Solutions, Inc.
You may use it for noncommercial purposes, provided this credit line is included in its entirety.

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