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How Big a solar system to get?
- Thread starter Piney999
- Start date
TheTalkingMule
Distributed Energy Enthusiast
Sorry to take this slightly off-topic, but the original question brings up another interesting one.
When are we going to stop pricing residential installs on a "per kW installed" basis? The hardware and installation costs barely go up when you scope a 6kW vs an 8kW array on the same roof since panels cost next to nothing. Why are we incentivizing customers to under-build?
When are we going to stop pricing residential installs on a "per kW installed" basis? The hardware and installation costs barely go up when you scope a 6kW vs an 8kW array on the same roof since panels cost next to nothing. Why are we incentivizing customers to under-build?
Except for ventilation required by code in the attic, my single-story house is pretty tight and the exterior walls are 2X6's, triple pane glass with interior wooden shutters over each window. If I was building a new house, I would certainly employ heat pumps, particularly on my longest runs from the water heater.
Attic ventilation in California homes built after 2010 is spelled out here:
Updated Code Requirements for Attic Ventilation and Radiant Barriers
Hehe, I was going to say 1.15x but again - mouse nuts. My system: 6.6 kW X 1.15x = 7.59. My inverter is rated at 7.6 kW but I wouldn't turn down one rated at 8 kW.
I think a good system today will cost over $1,000/panel installed (with everything). Few people are capable of buying all the part-pieces and installing it themselves. Labor is particularly expensive. Then, profit is not a nasty word either. Pretty good panels were flowing in from China until Obama slapped higher import taxes on panels. They're still flowing in though.
I think a lot of folks think that if they over-spec or over build their system they're going to get the same rate for excess power they send to Edison as they would pay for if using it. Hehe, doesn't work that way except for the utility, which takes your excess power in summer and gives you 2-3 cents kW. It then goes to the transformer where it is immediately used by the closest residence or business that demands it and Edison will sell them your excess, totally green power for 30 cents kW in the summer. Hmmm since when did grid maintenance cost 28 cents a kW? No, profit isn't a nasty word.
nwdiver
Well-Known Member
Impossible to say with the information provided. I usually try to get the biggest system the roof can support.
How many kWh do you use annually? How many miles do you drive?
How many kWh do you use annually? How many miles do you drive?
Depends on the rules in your state. In AL, for grid-tied solar you have to pay a "reserve capacity fee" of $5 per month per inverter nameplate kw. So, a 10 kw solar system costs you $50 per month just to be connected, wiping out most of your savings (in my case, all of my savings, since the "10 kw inverter" produces at most 8 kw, and that for about 20 minutes per day). So be aware of your state's rules, as you might want to go with a smaller system if you have the case, as I do, where customers with installed solar subsidize the cost of the grid for non-solar users.
TheTalkingMule
Distributed Energy Enthusiast
Profit is for sure a GOOD word, but I'm not worried about profit in immature markets when a quality installer should expect 20x more business 18 months from now. We've hit a point where hardware is a much smaller overall cost component relative to still sky-high static soft costs. And while labor is expensive, the incremental labor to take a 6kW array to 8kW is minimal.
I think it's going to cloud the decision of the OP on how to size his or her array. Costs are NOT nearly equal for each incremental kW installed(see: $1kW utility solar installs), so at some point under this pricing model it becomes compelling to size at 60% of total usage even though you might have the roof space for more. That's silly when you step back and look at it logically.
We're trying to build an entirely new energy structure based on renewables, certainly we should be installing as much solar as will fit on our optimal roof space and worry about storing the excess later. In order for consumers to make real market-based decisions perhaps they should be offered price points with static and variable costs segregated?
I think it's going to cloud the decision of the OP on how to size his or her array. Costs are NOT nearly equal for each incremental kW installed(see: $1kW utility solar installs), so at some point under this pricing model it becomes compelling to size at 60% of total usage even though you might have the roof space for more. That's silly when you step back and look at it logically.
We're trying to build an entirely new energy structure based on renewables, certainly we should be installing as much solar as will fit on our optimal roof space and worry about storing the excess later. In order for consumers to make real market-based decisions perhaps they should be offered price points with static and variable costs segregated?
The OP's roof may support a system far larger than he needs, so why over-build and over-spend? I might initially place in the infrastructure to support a larger system or additional panels in the future. Things like conduits, additional pull strings, racks, and frames, so long as they weren't unsightly. Yes, realistically you want to future-proof your system but you also want to pay it off at some point.
I'm not a proponent of giving away my clean electricity to Edison for peanuts, while they sell it to my neighbor that has a pool pump running 24 hours a day at 10-15 times what they paid me. Unless your motives are purely altruistic for the benefit of the environment, I wouldn't be spending more than I need to.
You may laugh but we need to be wary and vigilant of the day some politician may say we are not entitled to use the energy the sun provides to our panels but Edison is. Then, not only will you pay for your system; you'll pay Edison for all the power you generate......
SageBrush
REJECT Fascism
I feel for you brother. The utility is really deep into the pockets of your legislature. I thought California's CPUC was bad but this is more evidence of what utilities are doing to destroy the technology except for themselves. Terrible.
I might be wrong but I think unless you're totally off the grid, the utility grid is built to prevent you from running on battery power unless the grid is down. Am I right or wrong? Don't forget, even when you have solar, you are always using power from the grid, even during a midsummer's day when your system is producing peak power output - right?
IdaX
Member
While Jupiter and Pluto are totally awesome and all, you only really need 1 AU or so.
How Big a solar system to get?
In my vast experience, you definitely want to include at least the Oort Cloud.
on edit: $%^#$@!%!! IdaX just beat me to it while I was typing!
In my vast experience, you definitely want to include at least the Oort Cloud.
on edit: $%^#$@!%!! IdaX just beat me to it while I was typing!
SageBrush
REJECT Fascism
The so-called islanding you are thinking of takes PV offline when the grid is down so that utility workers are protected from energized lines they presumed were safe. Batteries are local to the home and are not affected by a down grid.
Are you sure? If the grid is up, you're always getting your power from the utility night or day. Are you telling me that at night or otherwise, I can choose to draw my power from a Powerwall 2.0 and circumvent the utility? I know it's bi-directional but I didn't think you could invoke it at will. What's the "black box" that disconnects the utility from your main panel and allows one to use batteries when the grid is up?
TheTalkingMule
Distributed Energy Enthusiast
Not everyone is going to have a roof with appropriate exposure. Shouldn't we be building out infrastructure that fits our reality just 5-10 years down the line?
Utilities being allowed to rip people off will be going away in short order. In an open distributed market not long from now, you'll want as much production capability as possible. Especially when storage costs next to nothing 5 years from now. People like us may be willing to upgrade in a few years, but I think most consumers want to install once.
I'm not saying we should necessarily over-build for any particular reason, but I think charging solar customers the same for every incremental kW is detrimental to progress. That's not how utilities buy their solar and look how well they're doing.
SageBrush
REJECT Fascism
The OP said he had a large roof and southern exposure. Southern exposure is optimal if east or west are the only alternatives.
Boy, I hope you're right but the evidence doesn't suggest that's going to be happening anytime soon.
