Off-grid capability
SydBeans
| Posted in Green Building Techniques on
We’re building a small one-story house (1300 sf) in a rural area outside of Atlanta and would like to be off-grid ready. At a recent tiny house expo, we were told that it wasn’t really possible to have a house that size run completely off solar. Does anyone know if that is the case? We do have access to public water, electricity, and propane gas. We’d like to use solar and a rainwater harvesting system. The house will likely be built with SIPs or ICF and there are lots of windows for natural lighting. Does anyone have experience using solar or rainwater harvesting systems for a house this size? Product recommendations?
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Replies
Syd,
The answer to you question -- "Is it possible to have a small house that runs completely off solar?" -- depends on your answers to two other questions:
1. How big is your budget?
2. Do you expect the PV modules (solar panels) to fit on your roof, or are you willing to install a large ground-mounted array?
There are several hurdles to your goal. One hurdle: Most off-grid homes (a) have no air conditioning, and (b) use propane or wood as fuel for space heating and domestic hot water.
Most off-grid homes have a battery that is sized to meet about three days of electricity usage. If you live somewhere that can have four or five days of cloudy weather in a row, as I do, it would be extraordinarily expensive to design an off-grid system for an all-solar house.
The usual solutions to these issues:
1. Don't try to use electricity for space heating or domestic hot water.
2. Learn to live without air conditioning.
3. Size your PV array and battery to meet about 70% or 80% of your anticipated electricity use, and use a gasoline-powered generator to charge your batteries in cloudy weather. This will be a lot cheaper than aiming for a 100% solar solution.
We would be prepared to cover the South-facing pitch of our roof with solar panels if the price is reasonable. Using the SIPs, we're expecting not to need to use a heating/cooling system much. We're also adapting our usage behavior now to try and acclimate, although the Atlanta area is very humid in the summer. Our lot is heavily wooded with covered porches on the front and rear, which should help.