Deciding on panels

[tdagner]

Hi All,

I have gotten the bug to install a solar system on my house. I bought my first home about 2 months ago, and always wanted to install a system. I had someone from power home solar come out to my house and give me a quote to do the install, and man was I floored by the price after I did a little research. He quoted me $29K for a 5kw system. I knew that I could install the system myself when I asked him how long it takes them to install and he told me 4-5 hours. I am very handy with anything, my grandpa was an electrician before he retired, and my brother was an electical project engineer for a few years installing wind turbines in Nebraska. So we got this.

Anyways, I have been looking into systems and really like the solar edge stuff. I am sold on their optimizers and inverter. It looks as straight forward as it can possibly get. Im not sure what panels to get though. The Solaria panels look like the best bang for the buck. They are all Black, 325W, decent price from Renvu, and their warranty is 25 years. I am looking at 20 panels, because that is the most I can fit on my roof(have to measure one more time, may be going with 18 for the 3 foot walkway around the panels) Does anyone have any suggestions on these panels??

I live in NC and have an azimuth of 196 Degrees, so my house is set up pretty well for production I believe?? I spoke with the county inspectors and I can install the entire system myself, so long as its up to code. Same with the power company(Duke), They will pay me 60 cents per watt of my system as an incentive to install one, so long as it passes inspection and I have 100K$ in liabilty insurance from my insurance company.

IM just at the beginning stages of doing this but I am itching to go and start saving some money on my power bill. Cost of everything from REnvu is quoted as $10,360 shipped to my door. After rebates and the tax incentive cost to me will be $3996, plus whatever other small items I decide to buy, Payback is a little over three years from now assuming an average power bill of 100$ per month.

Can someone help me determine if my system is large enough? I have only been in the house 2 months now, so I am unsure of what the power bill is going to be. This past month it was $43, but that is spring time where I didnt run the AC or Heat at all. The previous owners told me it averaged around $150 a month, which I am thinking I wont get near that price. I live here alone, water heater is now on demand gas, and the house is 2*6 construction with both foam insulation and the regular insualtion you put in the walls. Also, what am I missing? Am I right in thinking a 6.5KW system will cover the majority of my bill? Duke has net metering 1:1 in my state.

[J.P.M.]

Before you go farther, buy (@ bookstores/Amazon) "Solar Power Your home for Dummies". A decent/good primer.

Get familiar with PVWatts. Read the help screens a couple of times and use 10 % system losses rather than the 14 % default value.

Know and understand your electrical load and ways to reduce it more before PV. Any system after load reduction will be smaller, less expensive and easier to build. See the early parts of the book for energy efficiency pitches. Conservatyion is more cost effective than PV.

Come back here and fill in knowledge gaps after you read the book and after you do prelim. sizing w/PVWatts.

Get knowledgeable before you order stuff or pick up any tools. You'll have a safer, more cost effective and more fit for purpose system for having done the homework upfront.

Do not oversize a system unless you want to make it less cost effective. Think long term for both cost effectiveness and future needs, but do not oversize or get unrealistic about future needs. Everyone wants an EV. I only wonder how many to those wants will be realized or change. While considering future needs, keep in mind that net metering may well not be as sweet a deal in the future as it seems to be now. Things are changing.

Welcome to the neighborhood.

[tdagner]

Thanks for the help! I had no idea about the net metering rates possibly changing, that would suck to install a system just to have the power company. Are you typically grandfathered in if the rates change? I believe I have reduced my electrical load about as mush as possible. I have a 3 year old heatpump, and the first thing I did after moving in was to change every single lightbulb in the house to LED.

I have visited the PVWatts site, I just need to do it several more times before I get a real grasp on it.

[TAZ427]

Can someone help me determine if my system is large enough? I have only been in the house 2 months now, so I am unsure of what the power bill is going to be. This past month it was $43, but that is spring time where I didnt run the AC or Heat at all. The previous owners told me it averaged around $150 a month, which I am thinking I wont get near that price. I live here alone, water heater is now on demand gas, and the house is 2*6 construction with both foam insulation and the regular insualtion you put in the walls. Also, what am I missing? Am I right in thinking a 6.5KW system will cover the majority of my bill? Duke has net metering 1:1 in my state.

$6/W OMG, that's ridiculous... A quick google search showed it was about $3.24/W on avarege in Charlotte, NC, last Oct.

That said, yes, read 'Solar your home for dummies' and use PVwatts as JPM has recommend as a precursor to anything.

That said, you last paragraph was the best one. Can you get the previous owners actual usage? Often times the cost per month may be fairly offset because of the time of year usage. And you may (and likely have) observed the lowest consumption months that you'll see all year. It may even pay itself in dividends to at least sit through the summer months and see what your electricity consumption is going to be under your consumption. It sounds counter intuitive, but you likely don't want to over or under size your system.

[sdold]

He quoted me $29K for a 5kw system. I knew that I could install the system myself when I asked him how long it takes them to install and he told me 4-5 hours

Criminy! My 4 kW DIY system cost was around $8000 including permit fees, shipping, sales tax, everything, and that was four years ago. $2/watt. Unless you have a very difficult install for some reason, that quote is way out there.

I suppose Solaredge with optimizers is fine, I wouldn't like being locked in to a particular manufacturer for all of the electronics. Am I going to be able to buy an optimizer in 20 years?

[ButchDeal]

Am I going to be able to buy an optimizer in 20 years?

No!
No optimizers for you, 20 years.

[J.P.M.]

Thanks for the help! I had no idea about the net metering rates possibly changing, that would suck to install a system just to have the power company. Are you typically grandfathered in if the rates change? I believe I have reduced my electrical load about as mush as possible. I have a 3 year old heatpump, and the first thing I did after moving in was to change every single lightbulb in the house to LED.

I have visited the PVWatts site, I just need to do it several more times before I get a real grasp on it.

If the thanks are in my direction, you are most welcome. How much help the mental spoor might be is a matter of some opinion.

NEM rates and tariffs, like all rates and tariffs, are constantly changing, or at least probably not constant for very long. NEM tariffs are, in general, being revised as POCOs (POwer COmpanies) try to get out from under what they see as the yoke of unfairness of net metering. Some NEM rate, tariffs and users are grandfathered. Some are not. Some are a mix. It's probably reasonable to at least proceed on the assumption that net metering will not be as sweet a deal in the future as the past and a wise move to get at least somewhat familiar with how rates and tariffs that can affect you now and in the future are put together. To do so is a real PITA for sure, but what you don't know can hurt you.

As for load reduction, everyone's tolerance and threshold is different. Kind of like compromise: no one gets everything they want, but probably closer to what they can barely tolerate.

Use can always be reduced more. The question is what are you willing to pay in terms of inconvenience to save money ? Looked at in one way, life is a set of choices. Pay your money. Take your choice. Just be informed walking in. BTW, and meant as an example of paying for convenience, not a snide remark: Did you raise/lower the thermostat setting on the old heat pump before replacing it ?

[tdagner]

If the thanks are in my direction, you are most welcome. How much help the mental spoor might be is a matter of some opinion.

NEM rates and tariffs, like all rates and tariffs, are constantly changing, or at least probably not constant for very long. NEM tariffs are, in general, being revised as POCOs (POwer COmpanies) try to get out from under what they see as the yoke of unfairness of net metering. Some NEM rate, tariffs and users are grandfathered. Some are not. Some are a mix. It's probably reasonable to at least proceed on the assumption that net metering will not be as sweet a deal in the future as the past and a wise move to get at least somewhat familiar with how rates and tariffs that can affect you now and in the future are put together. To do so is a real PITA for sure, but what you don't know can hurt you.

As for load reduction, everyone's tolerance and threshold is different. Kind of like compromise: no one gets everything they want, but probably closer to what they can barely tolerate.

Use can always be reduced more. The question is what are you willing to pay in terms of inconvenience to save money ? Looked at in one way, life is a set of choices. Pay your money. Take your choice. Just be informed walking in. BTW, and meant as an example of paying for convenience, not a snide remark: Did you raise/lower the thermostat setting on the old heat pump before replacing it ?

The previous owners replaced the heat pump about 3 years ago. what I was meaning by I have a fairly new heatpump is the fact that it isnt 20 years old and inefficient.

I can get the previous usage from the past owners I think, just have to ask them for it. They were on an equal pay plan that was renewed right before they sold me the house @ $150 per month, so I am pretty sure that is average, but with 2 people living here, and they didnt have a single LED bulb in the entire house. I have around 50 recessed flood lights throughout the house that were all the old school 40-50 watt bulbs that are now all LED's, so I am thinking that will help out a bit. They also ran a dehumidifier in the crawlspace without a vapor barrier in place, that I know for a fact ran easily 15 hours a day. I have since but a vapor barrier down and will no longer need the dehumidifier(those things suck a ton of juice).

I hear you about waiting the summer out, but I am not sure how long my power company will have the funds to pay out the 60 cents per watt. On a 6500 watt system, you are talking about $3900. not something to just let pass you by. I think 22 panels is all I can fit on my south facing roof(need to measure again, couldnt find the tape measure when i measured the first time so i used my foot) which would give me 7150 watts. The difference in cost of 18 panels(5850 watts) and 22 panels(7150 watts) is only $187. I cant see a reason not to go with as large a system as my roof can fit based on that small increase in price, and not have to worry about it not being big enough. Id rather produce more than I need and be able able to run my AC at whatever temp I decided in the middle of the summer without a care in the world.

[J.P.M.]

TAZ427: Off topic for a second or two: I Just had a thought, and no particulars are needed or wanted on your part in the way of any response you may think appropriate that would violate your privacy. A member and a mod. here who lived/worked in N. County San Diego as an engineer (forum handle Sensij) took a job in the pacific NW a few months ago. Maybe I'm wrong, but I believe he worked here for a relatively small local outfit that made specialty tubing and small pipe fixturing, etc. using St. Stl. and some exotic metals, but NOMB, and I have every reason to believe he's done well and continues to do so. Might you have replaced him at his old position ? Stranger things have happened.

[TAZ427]

TAZ427: Off topic for a second or two: I Just had a thought, and no particulars are needed or wanted on your part in the way of any response you may think appropriate that would violate your privacy. A member and a mod. here who lived/worked in N. County San Diego as an engineer (forum handle Sensij) took a job in the pacific NW a few months ago. Maybe I'm wrong, but I believe he worked here for a relatively small local outfit that made specialty tubing and small pipe fixturing, etc. using St. Stl. and some exotic metals, but NOMB, and I have every reason to believe he's done well and continues to do so. Might you have replaced him at his old position ? Stranger things have happened.

Nope, didn't replace him, I'm an Electrical Engineer, and it sounds like he was possible a Mechanical Engineer. I don't see a need to hide it, I work for Intel now, I worked for Texas Instruments for 20yrs before moving out to CA. Being in the Semiconductor Industry tends to limit who you work for and where the jobs are available, which I believe may explain a bit more on another thread regarding thermodynamics...

[J.P.M.]

Nope, didn't replace him, I'm an Electrical Engineer, and it sounds like he was possible a Mechanical Engineer. I don't see a need to hide it, I work for Intel now, I worked for Texas Instruments for 20yrs before moving out to CA. Being in the Semiconductor Industry tends to limit who you work for and where the jobs are available, which I believe may explain a bit more on another thread regarding thermodynamics...

Understood. Some are more private than others and with good reason.. Thank you.