Better to over produce in anticipation of maybe hot tub and second EV?

[RegularDude]

If I’m installing panels now is it better to buy for my usage now or over produce in anticipation of a second EV or a hot tub in a year or two? Basically, is it cost prohibitive to add-on to a system later negating the cost of buying now for something I won’t use yet.

[Ampster]

If I’m installing panels now is it better to buy for my usage now or over produce in anticipation of a second EV or a hot tub in a year or two? Basically, is it cost prohibitive to add-on to a system later negating the cost of buying now for something I won’t use yet.

It all depends on where you are standing. I see from another post that you are in California and if you are concerned about the impact of NEM 3.0 adding capacity may be a hedge against further erosion of benefits. It can also be a hedge against inflation and in particular a hedge against some anticipated increases in consumption with an EV and/or hot tub.

Ultimately you will get a cross section of opinions and have to make the decision that suits your own risk profile and cost of funds.

[azdave]

My grid-tie agreement prohibited me installing more capacity than I currently averaged in the last 3 years of record. Telling them I had plans to add an EV or a hot tub soon would not have increased that production ceiling. Are you in a grid-tie situation?

[organic farmer]

If you stay within the mindset of net-metering / grid-tied systems, there appears to be a lot of other constraints. Focusing first on how much power you are currently using.

To build a big system with the intent that in the future it would allow you to do X, Y, Z other things, is more of an off-grid mindset.

I have had a jacuzzi / hot tub at three previous homes, and in each case they were massive power hogs. We currently have a plugin hybrid that we recharge from our solar power system. Ideally our system should be much bigger to support driving an EV.

[RegularDude]

It all depends on where you are standing. I see from another post that you are in California and if you are concerned about the impact of NEM 3.0 adding capacity may be a hedge against further erosion of benefits. It can also be a hedge against inflation and in particular a hedge against some anticipated increases in consumption with an EV and/or hot tub.

Ultimately you will get a cross section of opinions and have to make the decision that suits your own risk profile and cost of funds.

I’m definitely thinking of NEM 3.0. I assume if I add capacity SDGE will knock me off NEM 2.0 because they’re greedy like that.

[J.P.M.]

I’m definitely thinking of NEM 3.0. I assume if I add capacity SDGE will knock me off NEM 2.0 because they’re greedy like that.

Possibly, but probably not without doing something really contrary to NEM 2.0.
You can, for example, add up to 1 STC kW to an NEM 1.0 or 2.0 system without putting your NEM status in jeopardy.
As far as getting knocked off NEM 2.0 is concerned, where would you get knocked to ? NEM 3.0 doesn't exist yet. so, back to NEM 1.0 ?
I suppose you could get knocked off NEM altogether, but I've not heard of anyone having that happen to them - at least not yet.
As far as NEM 3.0 is concerned, that's still in the future and speculation as to what it may look like is probably a waste of time. I'd not assume anything about it just yet.

As far as what to design for, that's a matter of taking your best ball shot and knowing you'll probably not nail it. Such is life. Having goals, a stable lifestyle and knowing what you want out of life helps but there's nothing constant in life except change. If cost effectiveness is important to you, take the time to really examine your energy use and set priorities, maybe looking at the cost of convenience vs. a few more bucks in your pocket. Again, a matter of priorities and lifestyle. Oversizing based on uncertainly is one way to do it, but that's usually less than optimally cost effective as well as a front door invitation to something that can easily turn into a tool for a self-fulfilling prophesy in that you'll have all that excess capacity and will feel a need to use it, wisely or otherwise. On the other hand, gross undersizing, is not good either as it may not meet your needs.

Some consider the goldiocks method, at least with respect to cost effectiveness to lie in solar process economics.
From Duffie and Beckman:

"Solar processes are generally characterized by high first cost and low operating costs, Thus, the basic economic problem is one of comparing an initial known investment with future operating costs. Most solar energy processes (including PV - my add) usually require an auxiliary (i.e. conventional) energy source so that a complete system includes both solar and conventional equipment (or the grid) and annual loads are met by a combination of the energy sources. In essence, solar energy equipment is bought today to reduce tomorrow's energy bill."

Further to that, again from Duffie & Beckman: "The objective of the economic analysis can be viewed as the determination of the least cost method of meeting the energy need, considering both solar and non solar alternatives. For solar energy processes, the problem is to determine the size of the solar energy system that gives the lowest cost combination of solar and auxiliary energy."

But.....,, that's only after you've decided what you want the system (or systems) to produce. 3 EV's, an electrically heated hot tub and lots of toys will require more electricity than an off grid cabin. I'd suggest a realistic outlook at what you want for the future and knowing what it'll take energy wise to get while realizing you'll probably not be 100% on the mark for lots of reasons that are nobody's fault.

FWIW, and since you seem to be looking for opinions, I'd first sit down and take my best SWAG at what I want for the medium term future (10 -15 years maybe) in terms of lifestyle, and then estimate how much electricity it'll take to get there.
I'd then size and design a PV system with those future goals in mind using process economics as briefly described by Duffie a & Beckman.
As a matter of fact, that's pretty much what I did.

BTW, where in San Diego do you live ? I'm in 92026.

[RegularDude]

Well thought out response, I’m going to be in 92111. I didn’t know about the adding 1KW. It’s not much but something. Given there’s no proposal on NEM 3.0 it would make sense for me to sit tight at a reasonable system now and let the hot tub and future EV sort themselves out later or when 3.0 comes out.

[RichardCullip]

Personally, I would overproduce in anticipation of increased future use, that is, if your power provider allows it. You might find it hard to find a company that would come in and add on to an existing system.

In 2019 I installed a bigger system than my usage in anticipation of adding demand in the form of an EV in the future. I'm in SDG&E territory and had no problem adding a system that was bigger than my needs at that time. Flash forward three and half years and my cumulative bill from SDG&E is -$43.00. That's right, SDG&E owes me money (actually a credit carried forward into my current true up period).

This year I finally added an EV, dipping my toes into EVs by buying a RAV4 Prime. So far I've had enough excess power to keep it charged up and enjoying doing 95% of my travels on battery only. So far I've covered just a hair over 1,000miles on a 1/4 tank of gas (3.6 gals).

I realize that over-sizing a solar system is not optimal from an economic analysis perspective but I'm enjoying not paying SDG&E a dime for the past 3 1/2 years. In addition, I don't stress over when I use electricity.

[J.P.M.]

Personally, I would overproduce in anticipation of increased future use, that is, if your power provider allows it. You might find it hard to find a company that would come in and add on to an existing system.

In 2019 I installed a bigger system than my usage in anticipation of adding demand in the form of an EV in the future. I'm in SDG&E territory and had no problem adding a system that was bigger than my needs at that time. Flash forward three and half years and my cumulative bill from SDG&E is -$43.00. That's right, SDG&E owes me money (actually a credit carried forward into my current true up period).

This year I finally added an EV, dipping my toes into EVs by buying a RAV4 Prime. So far I've had enough excess power to keep it charged up and enjoying doing 95% of my travels on battery only. So far I've covered just a hair over 1,000miles on a 1/4 tank of gas (3.6 gals).

I realize that over-sizing a solar system is not optimal from an economic analysis perspective but I'm enjoying not paying SDG&E a dime for the past 3 1/2 years. In addition, I don't stress over when I use electricity.

Richard: How long did you wait for the Rav4 prime ?

Thanx,

J.P.M.

[RichardCullip]

Richard: How long did you wait for the Rav4 prime ?

Thanx,

J.P.M.

Started the search in January took delivery in June. Not the best time to try and buy a new car, especially a popular one like the RAV4 Prime

[peakbagger]

To the OP, my strong suggestion is have the racking installed and buy spare panels even if you park them on in the garage. Panels manufacturers are like car dealers, they seem to have new model all the time. Even if its the same model, there are variations in color over the course of the manufacture. There could be slight color variation if you wait to install them but that will normally fade away after a few months.

For the Rav 4 drift - I got my first Rav 4 Prime right off a lot when Toyota started shipping to the New England states, there was a small window early on when they were readily available. Unfortunately that one got totaled 3 days after I got it. By the time I got the check for replacement they were in demand, I got a replacement but had to pay 3K over sticker. That was more than offset by getting two EV credits so my net cost was under 30K. They are complex and the owners manual is thick and not that well organized but so far its the best car I have ever owned. All the plug in EV benefits but none of the limitations. My guess is Toyota loses money on every one they sell and are building them to offset CAFE standards and buy back some of the bad PR they got to their resistance to EVs.

[OCJ]

I am in SDG&E and oversized my system in anticipation of a larger house usage (moved from 2,100 sqft to 2,800 sqft), an EV, and a pool. Turns out this house is much more energy efficient, I did get the EV, and looking at the pool in the next year or two. I think I will have some excess production so I'm also considering putting an electric water heater inline with my gas on-demand water heater. Still looking at the economics of that one.

All in all, I'm glad I went larger. The 10-year payment for the system is still less than my average monthly cost would have been. After 10 years that payment drops off and I get some years of very little cost.

[Ampster]

......... I think I will have some excess production so I'm also considering putting an electric water heater inline with my gas on-demand water heater. Still looking at the economics of that one.

All in all, I'm glad I went larger. The 10-year payment for the system is still less than my average monthly cost would have been. After 10 years that payment drops off and I get some years of very little cost.

While natural gas is still the most efficient way to heat water a heat pump water heater is a lot more efficient than the standard resistive element electric water heater. A HPWH could also give you a hedge against rising natural gas prices if that is a concern.

[OCJ]

While natural gas is still the most efficient way to heat water a heat pump water heater is a lot more efficient than the standard resistive element electric water heater. A HPWH could also give you a hedge against rising natural gas prices if that is a concern.

That's definitely what I'm looking at. My concerns are space, since I currently have a wall mounted on-demand unit, and of course cost of the electric line, water heater, and installation. I want to put it inline before the natural gas on-demand heater so I could get away with a smaller one, but have the gas heater as a backup if it hasn't recovered enough. I have central gas heating and a gas range so I just don't see being able to totally eliminate gas at this point. Like you said i'm wanting to hedge a bit against natural gas prices as well as soak up that additional solar production.

[vballdad]

To the original poster.... I was in the same situation as you.
In 2017 we bought an 11.66 kw Solaredge system. Seven months of the year were zero usage.
In 2019 we added 8 kw to existing system.
Zero FPL usage to this point. FPL raised my minimum payment for zero usage from $10.77 to $29.95. So my excess credit is used up 3 times faster.
Our hopes (preorder list) are for a Lexus RZ450E to use the excess. Net metering pays us from $0.016 cents to $0.024 cents per KW. Not the $0.12 cents FPL tells customers.
In 2020 we upgraded 1 of our A/C's to a Trane 4 ton two speed. Saving an additional 4-8 kw daily in summer usage.
Hoping my other 2 Ton A/C will be similar savings when replaced. New appliances, Impact windows, and new paint, seeking ways to save with 3400 sq ft of A/C is a challenge.
All hot water is solar since 2010.
I hope I can offset the 10% expected inefficiency loss from panels