If their placement on the porch does not get direct sun, I would call it good enough for now, day and night.
Iguana care is not intuitive. Do you know the basics of keeping iguanas healthy and safe? Food, lighting, Relocation Stress, dehydration?:
Go to the top of the Green Iguana Society message board and click on Green Iguana Society Home. It has a good care sheet. And this is a complete iguana care document: http://www.anapsid.org/pdf/icfs.pdf All of us here would agree that you need to read all of this. It will save you the heartache and expense of sick and injured iguanas.
There is seldom a good outcome from keeping multiple iguanas. You need to know all you possibly can.