How Many Solar Panels Do I Need to Power My 3,000 Square Foot Home?
It’s a common question. “How many solar panels do I need to power my ### square foot house?”
The answer is not so simple. In fact, I can’t even give you a rule of thumb. Some industries can tell people a reasonable range for sizing equipment, and often building codes dictate sizing of appliances. For example, an A/C company might tell you that on average you need one ton of air conditioning for every 600 square feet of living area for a Southwest Florida home. A plumber might tell you that you need a minimum 50 gallon water heater for a 3 bedroom, 2 bath home. There is no such approximation with solar energy.
The energy used by a home, and more specifically a homeowner, can vary tremendously (note: homes don’t use energy – people do). My 3,000 square foot home uses about 2,000 kilowatt-hours (kWh) of electricity each month. I’ve been at a customer’s 2,500 square foot home that uses 3,500 kWh of energy! That would be a range of 0.67 – 1.4 kWh per square foot per month – hardly a useful range to use as a rule of thumb.
Energy use is complicated. People have very different habits, standards of living, and luxuries.
I was at a customer’s home where they had two refrigerators in the garage. That is the worst place to put a refrigerator in Florida (because of the ambient temperature). But two?! They were wondering why their electric bill was so high despite the installation of solar products. I think I have an idea…
Pool homes consume more energy generally. Old air conditioners and poor insulation cause poor efficiency for cooling. Some people run incandescent lights in their yard 12 hours a day. And many times, habits are the cause.
Even the utility company averages have little value. LCEC and FPL report about 1,100 kWh per residential account. However, that includes small condos, separately metered buildings, manufactured homes, and seasonal residents. It’s not a good metric to use – just about every customer we visit consumes more than the “average.”
What we need to know is how much energy you use. Fortunately, that’s easy to find out. Both utilities in Southwest Florida have online account history that shows you energy use by month. Fafco Solar’s solar advisers can help you figure out how much energy you are using and how many solar panels you need to power your house!
scott Says:
This article tells nothing. The question was simple. the answer resembled a political debate. How many panels and batteries are required to run a home in Florida? details…2100 sf, brand new construction, 3 br, 1 den, new air conditioner, 1 fridge, 1 stove, 1 microwave, 3 tvs, 1 computer, 20 outlets, no fridge in the garage, and oh yeay, an inground pool/hot tub. Is there a kw ratio to follow, or do we buy 100 batteries and 500 panels to make this happen? I really want solar energy in my new home and all the bs online is just confusing. No wonder more people dont do it. HELP!!!!
Posted on November 6th, 2012 at 2:48 pm
Jason Szumlanski Says:
The appliances you mentioned have certain power draws, and that power draw can vary. Furthermore, power is not energy. Energy is power over time. Answer these questions:
- What is the SEER of the A/C
- What temperature setting will you set on your thermostat?
- What is the R-Factor of your insulation?
- What is your roof type and color?
- What is the R-Value of your windows, where are they on the house, and what sun exposure do they have?
- What size fridge, what efficiency level, and how often do you plan to open the door?
- Do you cook at home, how often, and do you use your oven?
- How long do you watch each of your TVs? Do you unplug them when not watching? Will you have a cable box or DVR, and do they remain plugged in all the time?
- How long do you use your computer? What type? Desktop? Laptop?
- What’s plugged into the outlets? How long?
- What size pool pump do you have? How long do you run it?
- Do you heat your hot tub? How hot? How long What time of year?
Obviously, I don’t really want you to answer these questions, and this isn’t easy to figure out, but there is hope. If you jump to the last paragraph of the post, I mentioned that your utility company provides tools to tell us how much energy you use. That’s great if your goal is to get to net-zero utility bills. However, the energy you use in your home is irrelevant to the energy you produce!
The better question is, “How much solar energy can I produce at my house?” That’s a simple question to answer. based on the available roof space, we can determine how much energy production potential your home has, and how much you can offset your electricity bill in terms of dollars.
The point is, we need more information about your goals to help you understand your solar options. It’s really not as hard as I made it sound, perhaps. If your goal is to reduce your electricity bill to zero, we just need to know what your current usage is to tell you if it is possible and practical. If you just want to make a dent in your bill, we can tell you what it takes… Simple!
If you want a simple formula or a rule of thumb for Southwest Florida, assume that a 1 kilowatt (kW) solar energy system will produce approximately 1,400 kilowatt-hours per year. If you use 14,000 kWh per year, you need a 10kW system to get to net-zero.
Posted on November 6th, 2012 at 3:25 pm