We are still working on finding a builder for our custom home in Colorado. We are very close to making a decision. In the meantime we are thinking about all the different parts and peices that will make the home work. One of the most important parts is our solar power system.
The house is going to be tied to the power grid. So the solar power system will indirectly generate the power we use giving us a $0 power bill each month. That means we need to build a solar power system that is at least as large as all of the electricity our home will use. An extra complexity is that our local power company only allows us to have a system that is 120% of our overall usage.
So we used this online calculator for an off-grid solar system to get an estimate of what our home will use on day 1, plus we added an Electric Vehicle Level 2 charger. We figure that within 5 years we will have an EV and will want to be able to fast charge it at home.
Here are the numbers:
| Appliance | Quantity | Watts | Hours On per Day | Watt Hours per Day |
| LED Bulb – 60 Watt Equivalent | 25 | 13 | 6 | 1950 |
| Fridge – 20 cu. ft. (AC) | 1 | 353 | 4 | 1412 |
| TV – LCD | 2 | 150 | 9 | 2700 |
| Laptop | 2 | 100 | 14 | 2800 |
| Router | 1 | 7 | 24 | 168 |
| Modem | 1 | 7 | 24 | 168 |
| Smart Phone- Recharge | 2 | 6 | 3 | 36 |
| Water Heater – Electric | 1 | 4500 | 1.5 | 6750 |
| Oven – Electric | 1 | 1200 | 1 | 1200 |
| Clothes Dryer – Electric | 1 | 3000 | 0.5 | 1500 |
| Clothes Washer | 1 | 800 | 0.2 | 160 |
| TV – LCD | 2 | 150 | 12 | 3600 |
| Blender | 1 | 1500 | 0.2 | 300 |
| Circular Saw 8-1/4″ | 1 | 1400 | 1 | 1400 |
| Hottub | 1 | 5000 | 6 | 30000 |
| EV Level 2 Charger | 1 | 11500 | 1 | 11500 |
| System Calculation Results | ||||
| Killowatt Hours per Month: | 1,969 kWh | |||
| Peak Load: | 30,404 watts | |||
| Sun Hours: | 4.75 hours/day | |||
| System Size: | 16.58 kW |
This helps us understand that we will want to max out our south facing roof with 42 solar panels. At 330Watts per panel that gives us just over a 13kW system to start with. We still have the roof on the garage which could handle another 40 panels. So we will want to get an Inverter that allows for expansion.
The next step is working with the power company to get approval. Then figuring out if we want or can roll this equipment into the mortgage of the house.
Lots to think about.