Thank you for many practical directives relating to solar power through your magazine articles.
Our family is in the process of transitioning our home to solar just north of Raleigh, North Carolina. The first step has been to change the lighting through-out to energy efficient. Now we are in the process of transitioning to energy efficient appliances. The next phase will be purchasing inverter, solar panels and finally batteries.
The questions we have are the following:
1. We wish to set up the system to be utilized for non-major appliances. Solar will not be used then for ac/heating, washer/dryer, or water heater. Can the wiring be direct-wired (with ac fuses) from the inverter to the respective circuits in the home fuse box?
2. Any recommendation of solar panel distributors in the eastern part of the US? We likely will purchase panels for a 1.2kw array. It appears most of the distributors in the US are from the west and the current shipping rate greatly increases the price of panels.
3. For a 1.2kw system, likely with a 12 volt, 2000 watt xantrex inverter, would ask what would be the most feasible set-up for the battery back-up?
The last phase of the project will be to install a solar thermal heater. Not sure if we will buy or build it… to be determined.
There may be some inquiry on your part to give more precision to these questions. Please ask.
Jon and Mary-Lou Kroeze
Jon and Mary-Lou:
Sounds like you are off to a good start by first reducing your energy loads. Directing the energy from an inverter tgo specific electrical loads is easy, just treat it like a backup generator and install a second circuit breaker panel. These are usually 100 amp panels having 8 to 12 circuits. You remove those circuits from the existing main panel and re-route to this panel for each circuit you want to be supplied from the backup power system.
Most higher quality inverters will include a built-in transfer switch which will route the utility power from your existing main panel into the inverter then out to the new emergency panel. This will require installing a new circuit breaker in the existing main panel to supply the inverter, which in turn feeds the new emergency loads panel. Most inverters can be programmed to supply the new emergency loads from a solar charged battery until the battery gets low, then switch to either a generator or back to utility grid power coming from the main house panel.
I disagree with your choice of a 2000 watt 12 volt inverter. This is way too small for this type application, and the low 12 volt DC input would require a very high current draw and large battery wire size. The higher the battery voltage, the less wear and tear on the inverter and the smaller the battery cables and fuses. If you are considering a DC refrigerator or freezer, you may need to select an inverter based on the battery voltage required for this DC load. However, 24 volts is the lowest system voltage I would recommend, and 48 volt is not out of the question. Never under-size the inverter if you have budget problems. You can always add more solar modules later, but you do not want to under-size the inverter and then have to replace it later with a larger unit.
Finally, you should not have any problem finding a solar dealer in North Carolina. I was asked to teach a 3-day solar installers course several years ago for the North Carolina Solar Energy Center, and there were many electricians and contractors attending this class. Your state is very active in promoting solar and you should be able to find a good solar installer through the State Energy office.
P.S. Tell them hello from me!