Solar Panel Installation?

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Joel
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Solar Panel Installation?

Post by Joel » Wed Oct 03, 2018 10:36 pm

Advice needed. We live in Northern California (greater Sacramento area) with great sun exposure and lots of AC usage. We purchased a new high-end HVAC system in May that did an excellent job this summer. The previous 12 months energy usage was only 5,050kwh for a 2,300 sq. ft. house. With the big HVAC upgrade, I expect our annual consumption to decrease even further as October through May were with the older HVAC system that was not nearly as efficient, however, it is difficult to quantify at this point.

With that said, I want to purchase solar panels for both financial reasons and environmental reasons. I'm hugely incentivized to do this by the end of 2019 to take advantage of the 30% tax credit before it gets slightly reduced. I plan to purchase outright and pay cash. I will not be financing, and I definitely won't be leasing or doing any type of power purchase arrangement nonsense where I don't own the panels.

Having said that, I've shared my detailed month-by-month usage with a few vendors and they are ALL recommending a system that produces ~105% of our actual usage. When I used PG&E's solar tool, they recommended a system with only 85% of our usage. Obviously, each solar panel that you purchase costs more money, and has less marginal improvement based on PG&E's tiered pricing structure. Whenever I push on the sales rep about why they are suggesting such a big system, they always turn it around that they always recommend more than 100% so that we could get more comfortable and use more electricity and not have to worry. They are obviously incentivized to sell more panels, so I immediately have a distaste for their sales tactics.

With all that said, when I try to google how big of a system should I buy, I just get blasted with a slew of advertisements for different solar companies. I can't seem to find any unbiased advice. So, do you have any recommendations on where to find unbiased advice on solar system sizing? Or do you have any unbiased advice yourself?

Please share! Thanks in advance!
My investment policy statement: https://www.bogleheads.org/forum/viewtopic.php?t=190093

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dgm
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Re: Solar Panel Installation?

Post by dgm » Wed Oct 03, 2018 11:06 pm

Joel wrote:
Wed Oct 03, 2018 10:36 pm
Advice needed. We live in Northern California (greater Sacramento area) with great sun exposure and lots of AC usage. We purchased a new high-end HVAC system in May that did an excellent job this summer. The previous 12 months energy usage was only 5,050kwh for a 2,300 sq. ft. house. With the big HVAC upgrade, I expect our annual consumption to decrease even further as October through May were with the older HVAC system that was not nearly as efficient, however, it is difficult to quantify at this point.

With that said, I want to purchase solar panels for both financial reasons and environmental reasons. I'm hugely incentivized to do this by the end of 2019 to take advantage of the 30% tax credit before it gets slightly reduced. I plan to purchase outright and pay cash. I will not be financing, and I definitely won't be leasing or doing any type of power purchase arrangement nonsense where I don't own the panels.

Having said that, I've shared my detailed month-by-month usage with a few vendors and they are ALL recommending a system that produces ~105% of our actual usage. When I used PG&E's solar tool, they recommended a system with only 85% of our usage. Obviously, each solar panel that you purchase costs more money, and has less marginal improvement based on PG&E's tiered pricing structure. Whenever I push on the sales rep about why they are suggesting such a big system, they always turn it around that they always recommend more than 100% so that we could get more comfortable and use more electricity and not have to worry. They are obviously incentivized to sell more panels, so I immediately have a distaste for their sales tactics.

With all that said, when I try to google how big of a system should I buy, I just get blasted with a slew of advertisements for different solar companies. I can't seem to find any unbiased advice. So, do you have any recommendations on where to find unbiased advice on solar system sizing? Or do you have any unbiased advice yourself?

Please share! Thanks in advance!
Here is my advice:
It depends on your life situation. Do you have kids who will be soon leaving the house to go to college? do you have kids in the house? A baby on the way? We have young kids in the house and because of that, plus general trends of more electricity usage as the years go by, we got a bit over our last year's usage -- 120% or so. So far I am seeing that was the right choice since our electricity usage is marginally higher this year (plus occasional cover means the panels are not 100% productive -- we live in the bay area)

In your case it seems like your historical usage is a bit high relative to what you expect going forward due to your HVAC upgrades so maybe 85% or so is the right place to be. Just realize once you put it in, adding an "extra panel later" is going to be too costly to be practical so think a bit about that.

Joel
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Re: Solar Panel Installation?

Post by Joel » Wed Oct 03, 2018 11:30 pm

We currently have an almost 1yo and plan for 1-2 more, so we are definitely likely to see increased usage in the future (how much? I don’t know?) that will be offset some by the savings as a result of the new hvac unit (entirely? I don’t know)

I definitely am struggling with how to weight and factor these situations into the calculation.
My investment policy statement: https://www.bogleheads.org/forum/viewtopic.php?t=190093

Joel
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Re: Solar Panel Installation?

Post by Joel » Wed Oct 03, 2018 11:35 pm

Another consideration, we may end up getting an electric car in the future (no immediate plans), and at that point the additional usage (an extra 3k+ kWh) could be a sizable enough expansion to the solar array that it could make sense to expand. Idk.
My investment policy statement: https://www.bogleheads.org/forum/viewtopic.php?t=190093

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willthrill81
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Re: Solar Panel Installation?

Post by willthrill81 » Wed Oct 03, 2018 11:41 pm

I've never heard of anyone with solar panels in any situation at any time wish that they had fewer than they did. The lone exception might be hikers.

Many experts recommend getting as many solar panels as you can afford or fit in their designated space, whichever is less.
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings

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dgm
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Re: Solar Panel Installation?

Post by dgm » Thu Oct 04, 2018 12:01 am

- If you don't plan on an electric car in the immediate future I wouldn't add the extra capacity now. I'd install the current panels with the intention of adding more capacity later (keep room available on the roof). Panels will get better/cheaper so I don't think getting the extra now is worth it.
- If you have a kid and plan to have more, they will eat up a lot of electricity -- more laundry, dishes, lights, electronics...I'd definitely err on the overcapacity side.
- I agree about no one wanting less solar panels. I got 20% more than my estimated usage and feel like I should've gotten a bit more.

wxl31
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Re: Solar Panel Installation?

Post by wxl31 » Thu Oct 04, 2018 12:12 am

Joel wrote:
Wed Oct 03, 2018 10:36 pm
With all that said, when I try to google how big of a system should I buy, I just get blasted with a slew of advertisements for different solar companies. I can't seem to find any unbiased advice. So, do you have any recommendations on where to find unbiased advice on solar system sizing? Or do you have any unbiased advice yourself?
Some solar salesmen are on par with used car salesman but I would say their recommendation to add slightly extra capacity is legitimate. From my experience, after installing solar, there is an "energy-using" creep - all of a sudden, AC is run at 72 instead of 74 or lights get accidentally left on more often or the washer/dryer is used more frequent for smaller loads than before because "solar". Add me to the club that bought what I thought was just the right amount of solar panels, who now regrets not getting more.

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unclescrooge
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Re: Solar Panel Installation?

Post by unclescrooge » Thu Oct 04, 2018 12:24 am

When I turned 40 I decided I was too old to suffer the heat.

I crank the AC to 74 in peak summer. We also put in a wine cooler. And we have an electric water heater.

I threw a couple of extra panels on the roof. The marginal cost is negligible. Solar panels are probably only 25% the cost of the project.

Currently we are scheduled to get a $730 rebate at the end of the year from the power company due to excess production.

In 10 years our kids will be teenagers, and we will both have electric vehicles. I expect the rebate will go negative at that time.

HIinvestor
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Re: Solar Panel Installation?

Post by HIinvestor » Thu Oct 04, 2018 1:01 am

We are empty nesters and bought about what we’re using, which is quite low. We mainly run our computers, fridge. We also gave solar water heater with its own panel. We do notice when our young adults visit, our electricity usage does increase a bit.

It seems we bought about the right amount as we rarely ever pay more than the minimum to stay connected to the grid. When we produce more than we use, our electric company gives us credit to be used against overcast times or high usage months. Our utility does NOT offer rebates.

We were happy when we installed we got s 35% rebate from our state and 30% fed rebate. We still haven’t purchased an electric car so don’t miss not having installed the extra panels.

All the estimators suggested similar amounts of panels to produce about 100% of our average monthly bill. We are satisfied.

Valuethinker
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Re: Solar Panel Installation?

Post by Valuethinker » Thu Oct 04, 2018 2:41 am

dgm wrote:
Thu Oct 04, 2018 12:01 am
- If you don't plan on an electric car in the immediate future I wouldn't add the extra capacity now. I'd install the current panels with the intention of adding more capacity later (keep room available on the roof). Panels will get better/cheaper so I don't think getting the extra now is worth it.
- If you have a kid and plan to have more, they will eat up a lot of electricity -- more laundry, dishes, lights, electronics...I'd definitely err on the overcapacity side.
- I agree about no one wanting less solar panels. I got 20% more than my estimated usage and feel like I should've gotten a bit more.
This is all good advice BUT

at least here, to install solar panels on the roof you need scaffolding (health and safety re workers require it as well as practicality).

That's a big fixed cost (plus hassle, plus security risk as you have just built a ladder into your upper floor windows).

So you want to do that as little as possible.

That might be a consideration. The cost of adding later to the array.

clutchied
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Re: Solar Panel Installation?

Post by clutchied » Thu Oct 04, 2018 11:31 am

As a data point for sizing:

We have a 6.73 kWh system in socal that is not super well angled but ok. It has through September produced 8.16 megawatt hours.

In CA you can undersize the systems b/c the sun hours are so high. run your own PVWatts calc though!

SmallSaver
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Re: Solar Panel Installation?

Post by SmallSaver » Thu Oct 04, 2018 11:47 am

Joel,

The finances will depend very much on your utility, namely (1) the interconnection agreement (net metering); (2) the rate structure (e.g. tiered pricing).

Interconnection agreement How are you compensated for times when your system is producing more electricity than you are using? For example, where I am when you are producing more than you're using you earn a credit, and you do it at the full retail rate of electricity. These credits roll over month-to-month but, importantly, once a year any excess credits are extinguished ("true-up"). That is, you receive no financial benefit if your total annual production exceeds your total annual use. I don't know what your situation is, but you should find out.

Rate structure If you have a tiered rate structure, the marginal benefit of additional panels gets lower as you get into less and less total use for the month. This is less important than the point above, which is pretty critical.

Finally, you should be able to work with your installer to keep future expansion as a possibility, basically by being strategic about how the panels are positioned and in selection of the inverter.

Good luck!
Last edited by SmallSaver on Thu Oct 04, 2018 11:54 am, edited 1 time in total.

Thegame14
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Re: Solar Panel Installation?

Post by Thegame14 » Thu Oct 04, 2018 11:50 am

I used this website to get a few quotes, went with a more local person that had good reviews, but used this as a basis to negotiate price

https://www.energysage.com/

Hug401k
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Re: Solar Panel Installation?

Post by Hug401k » Thu Oct 04, 2018 8:14 pm

I just chose based on the space I had where it would look good, and what had the quickest payoff.

PaulK
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Re: Solar Panel Installation?

Post by PaulK » Thu Oct 04, 2018 9:53 pm

We had SunPower install a 8.97KWh system a few years ago, and are very happy to be paying the minimum electricity bill, even during the hot summer months, when we use our AC almost every day.

The factors that will contribute to your calculation if your goal is to minimize your bill to zero should include
the type of utility usage plan you have or plan to have with your solar system. We used to have a tiered plan, but happy we switched to a TOA or time of use plan. The TOA is good for people who are not going to be using much electricity during the peak hours. My wife and I both work, and our TOA peak is defined as 1pm to 7pm M-F, while partial peak is 5pm-9pm M-F, 5pm-8pm Sa-Su during PDT. For PST, partial peak is 5pm-8pm M-F. All other times are Off Peak.

During peak hours, when our use is usually the lowest (except when we are off, staying at home), electricity costs are $0.3749/KWh. Partial-peak is $0.25963/KWh, and Off-Peak is $0.18285. So, you can see that if you generated an excess of 40KWh during the day at peak, during Off-Peak you could use nearly double that and still have a net cost of 0.

The problem now is that PG&E, our utility in the Bay Area, is not making money from solar customers, so they are changing the rules for new solar users that want a TOA plan. Rather than having the peak defined during the day, they are moving the hours to cover from 3pm-9pm. To counter this change in the TOA hours, you can add a battery to your system, and not use power off the grid until Off-Peak hours, and/or, you can have a bigger system. You'll need to crunch the numbers. Eventually, I plan to add a battery (Tesla Power Wall), when the prices come down as PG&E is going to eventually phase out the earlier TOA users to the newer times. Also, the latest TOA plans do not have the same cost differential between Peak and Off-Peak, so the cost of 1KWh during peak will not be 2X off-peak.

So, consider when you will need power, and how they align with your utility plan.

If I were installing a new system, I would go with the 105% system if I had the room, over the 85% system that PG&E recommends. Then, you can use power anytime you want, and not have to worry about the time of use in order to have a minimum electricity bill (PG&E charges a minimum of $9.x/month, but if you generate more power during the year than you would receive a credit (PG&E would pay you at the wholesale rate)).

Joel
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Re: Solar Panel Installation?

Post by Joel » Thu Oct 04, 2018 11:15 pm

California has net metering, but the annual excess payout is pennies on the dollar. So 100% is good, but anything above that’s worthless.
My investment policy statement: https://www.bogleheads.org/forum/viewtopic.php?t=190093

mervinj7
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Re: Solar Panel Installation?

Post by mervinj7 » Thu Oct 04, 2018 11:48 pm

Joel wrote:
Thu Oct 04, 2018 11:15 pm
California has net metering, but the annual excess payout is pennies on the dollar. So 100% is good, but anything above that’s worthless.
That's not true for all of CA. Where I live, excess production is paid out at retail rate, not wholesale rate. It's well worth it to oversize the system in this case.

https://www.svcleanenergy.org/solar/

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unclescrooge
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Re: Solar Panel Installation?

Post by unclescrooge » Fri Oct 05, 2018 12:22 am

Joel wrote:
Thu Oct 04, 2018 11:15 pm
California has net metering, but the annual excess payout is pennies on the dollar. So 100% is good, but anything above that’s worthless.
Where I live reimbursement is less than I pay, but it's not pennies.
Maybe 40% of my top tier rate.

Cruise
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Re: Solar Panel Installation?

Post by Cruise » Fri Oct 05, 2018 4:11 am

I had estimates from two firms, and each gave similar recommendations, 100% coverage. Five years later, the system has paid for itself. I do produce more electricity than I need, suggesting overcapacity. I couldn’t care less, as I can use my AC anytime without cost consideration. Another factor is the added value a larger system in a home sale scenario. Finally, if we buy a couple of Teslas or invite a relative to live with us, we won’t feel the impact.

mmcmonster
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Re: Solar Panel Installation?

Post by mmcmonster » Fri Oct 05, 2018 5:11 am

As a new solar purchaser, we ended up with 108% of our previous year's usage.

Reasons include:
1 - Kids are getting into middle and high school and will be coming straight home and spend more time up later at night.
2 - Comfort in keeping AC a little cooler.
3 - Consideration for a second electric (or plugin electric) car in the future.

On the other hand, my good friend got 108% on his roof and the system looks not as nice because he's got panels on three sides of the house. He needed so many panels because his useage is much higher than mine. (The reason is that he has older relatives living with him 9 months of the year.)

At some point the kids will move out and our usage will go down.

A lot of factors to consider, but I will say that so far it works entirely flawless. Best of luck. :beer

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