Off Grid Solar Homes

Erica Said:

i need to know how many solar panels it takes to run my home off the grid,anyone knowhow to find out?

We Answered:

This will get kinda long.

If I understand your question right you want to go off grid and have a stand-alone system that has no connection to the grid at all.

You are normally talking about a large system when you remove the grid. The Grid is your battery backup system so to speak. Plus it is a way to get a little return on your investment. You will need twice the size of a system to go off grid which would never pay for it's self and would be very very wasteful.

Off grid means you have to supply all your power for everything. This means an extra large battery bank. Like a weeks worth of power supply just in batteries. You need a minimum of 5% rate of charge just to charge the batteries. This means you still need to power your day time items while storing up power for night time use.

So first off I think you should go grid tie with battery backup and forget the glorius idea of being totaly off grid. It is just not that smart if you have the grid near by.

To go off grid you will need to add up all the wattage of every item that could be turned on at the same time. Water heater, TV set, A couple lights, Microwave, freezer, Coffee pot. You need to know the largest load to get the size of the inverter. You could need 4 inverters to have enough power to cover all your needs when one would do if you were grid tied.

Next being you are off grid you need to take your last twelve months electric bills and total the kWhs. And divide it by 365 to get your daily usage. Times 7 days. Divide this 7 days Wattage by 48 volts (battery voltage). This will tell you how many Amp Hours in battery power you will need to get you through 7 days of rain.
You never want to drain a battery bank below 50% discharge so you need to double the Amp Hour of the battery bank.
Now you have your inverter size and your battery bank size.

Now you need solar panels. And you should put 10% rate of charge on the battery bank. But you have to keep in mind that you only have so many Peak Sun hours in a day. Some places get 4 and some places get 6 hours. You will have to keep this in mind when you size the solar array.

I still think grid tie with battery backup is the best way to go.

Here are a couple of links that will help.

This link has other links that will take you to more information on how to size a system.…

Here is a design guide. Will take an hour or so to fill out.…

Julie Said:

I want a career in assessing homes to become more green/ being a contractor for homes being built off the grid?

We Answered:

Since you are approaching it from the perspective of someone wanting to become a construction contractor, you need to get into vocational school building trades programs.

The way it shapes up normally, you would end up being the general contractor hiring/contracting subcontractors for the electrical, for the plumbing, for the concrete work, for the septic install, etc, partly because of the specialty nature of the fields, but also the permitting requirement stipulations as well as the limits placed upon your contractor's license.

If you chose to double major, I would strongly suggest either civil engineering or soils engineering.

Meeting code requirements is not difficult, getting certifications is do-able, but getting hired, or contracted- that is another matter. Getting referrals- that is the hard part, but crucial to the survival of you as a general contractor.

One thing you do need to understand too is a lot of people going off grid- they are not hiring contractors. Some will, and there are some things they need to for the sake of insurability.

As for companies hiring Enviro E's? You went into that field without knowing who you might be working for? At least you did not go for the Renaisance Lit degree.

Most probably the Enviro E degree will get you into municipal or state government if you have some soil engineering background or civil engineering background, otherwise solid waste companies, pollution/contamination remidation companies, or groups like Green Peace or Sierra Club.

As far as composting toilets go for example- Knowing which units of governments allow for them and which ones don't is about the extent of it- they are a lot like an old TV set, they take up a lot space, and are self contained. You are not building one for someone else to buy, you buy them ready made. Outdoor commodes inmost areas do not pass muster- while if correctly maintained they can be environmentally friendly, many state health departments do not see it that way.

I would suggest too, try get some work over summer as a construction laborer. Learn how the structures are built. while some may have an innate knack for doing things right the first time- many don't.

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