Author Topic: Assist in creating a DIY Guide to Installing Grid Tied Solar on your Home.  (Read 2122 times)

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Offline DougSpindler

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I live in California in the San Francisco Bay Area.  I've been looking into installing solar for a couple of years now but have very little confidence in any of the companies who install solar.  I consume 10,000 kWhrs of electricity per year and have received quotes from $15,000 for 6 panels to $45,000 for 42 panels to "perfect" solar system for my house.  Let’s just say I’m feed up with the bull-shit I’m being told by the uninformed “well trained, state licensed solar experts”.   

As I research the cost of installing solar, the more I realize what a cash cow this is for the solar sales folks.  I have no problem paying for services, but when I know more than they do, then I have a problem.
I'd like to create this post to help me and others install a solar system on their home.  Our local power company, PG&E has what has to be the most expensive rates in all of the United States if not the world.  For the rate plan I am on I’m paying at times $0.45 kWhr.  And other PGE&E customers are paying up to $0.85 kWhr.  At $0.45 kWhr let’s say I a really motivated right now.

My local power company
Power company:  PG&E.  Power company offers 9 different rate plans for residential customers.
Tiered, straight Time of Use and Tired Time of Use.  Customers must pick one of the 9 rate plans and can’t change it for 1 year.
Rate plan I am on is straight Time of Use.  I am charged six different rates depending on the time of day and day of the year.  Rates range from $0.12 to $0.45.  In one day I can be charged 5 different rates.

In the past the agreement with the power company was if customers solar system over produced 1 kWhr it would be loaned to the power company until the customer needed it.  And when the customer needed to consume a KWhr they could cash in on that loan and get it back at no cost.  At the end of the year there would be an annual true up.  Customers who had credits with the power company would receive $0.02 kWhr as a credit on their bill.
That was in the past.  The way our power company is doing this is based on fair market value of the kWHr when it is purchased or “sold” to the power company.  This means when the power company is charging $0.45 kWhr for electricity I can “sell” any extra kWhrs to the power company at $0.45.  But then later in the day when the power company is charging $0.12 I can “buy” back the kWhr I “sold” to them at $0.45 for just $0.12.  None of the solar companies I have talked to understand this let alone know how to design for Time of Use customers. 
I use 10,000 kWhrs annually.  Under ideal conditions if I could “sell” all the power I produce at $0.45 and buy the power back at $0.12.  This means when it comes to sizing a solar system for my house I only need a system which generates about 3,000 kWhrs per year (which I sell to the power company at $0.45) to cover the 10,000 kWhrs consume every year at $0.12. 


 

Offline DougSpindler

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My situation
I use about 10,000 kWhrs of electricity per year.  But let’s call it 12,000 for future growth. 
I am on a straight Time of Use Rate plan, there is no tiering.
Power company has winter rates, and summer rates.  Off-peak, partial-peak and peak.
Winter rates are $.012, $0.22 and $0.32 kWhr.  Summer rates $.012, $0.24 and $0.45 kWhr
M-F there the rate changes 5 times per day.  Weekends we have 3.
We have net metering.  We don’t trade kwhrs with the power company.  Extra kWhrs are sold to the power company at the time produces for an energy credit in $ $.  So for every kWhr I “sell”/receive a credit for with the power company I can use that $$$ energy credit to “buy” kWhr back at a lower rate. 
Peak hours begin at 2:00pm M-F.
House faces 190 – Should be ideal for solar production.  I have an east and west facing roof surface I could use. 
At 38 north Latitude
Roof is in full sun all year.  No trees or obstructions.
My electricity usage has been consistent. 
Very little during partial-peak hrs (M-F mornings – 2:00pm)
And very little during peak hrs (2:00 pm)
Most of my electricity (65%)consumption is during off-peak hours
« Last Edit: April 27, 2018, 03:34:14 am by DougSpindler »
 

Offline ez24

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Not sure if there is a question here.  Mine is - are you going to install it yourself?  How about permits?  I know if you are going to "tie" in, you will need permits.  That alone might make it worth it to pay someone else.  There might be a solar permit business?

With 42 panels you can do a lot of things, like take up pottery as a hobby (electric kilns).  A big smile on your face when you open your electric bill.

Maybe start a protest by setting up electric heaters in your front yard (against the tiers).
YouTube and Website Electronic Resources ------>  https://www.eevblog.com/forum/other-blog-specific/a/msg1341166/#msg1341166
 

Offline DougSpindler

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Here's my first question...  Which direction should the solar panels be facing. 

I know for maximum solar panel production in kHrs one would favor a south orientation but that's no longer the best design for Time of Use customers.

I'm thinking west is the preferred direction to maximize energy credits in
with my power company as they "pay"/credit either 2 or 375 times more for kWhrs produced during peak hours.   I would think with four west facing panels I would have the same benefit as 6 or 7 panels facing south and 8 facing east.

Any thoughts?
« Last Edit: April 17, 2018, 09:38:08 am by DougSpindler »
 

Offline ez24

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I'm thinking west is the prefered direction to maximize energy credits in $$$$ with my power comapny as they "pay"/credit either 2 or 375 times more for kWhrs produced during peak hours.   I would think with four west facing panels I would have the same benift as 6 or 7 panles facing south and 8 facing east.


You can "preview" and correct spelling errors (they are underlined in red) and format errors. (the dollar signs showed up as "math error" - never saw this before).

 There are many solar installation apps (both Apple and Android).  My friend used one to predict shadows from trees.  I bet you can find one on tier pricing.  But anyway this is interesting.

YouTube and Website Electronic Resources ------>  https://www.eevblog.com/forum/other-blog-specific/a/msg1341166/#msg1341166
 

Offline DougSpindler

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Not sure if there is a question here.  Mine is - are you going to install it yourself?  How about permits?  I know if you are going to "tie" in, you will need permits.  That alone might make it worth it to pay someone else.  There might be a solar permit business?

With 42 panels you can do a lot of things, like take up pottery as a hobby (electric kilns).  A big smile on your face when you open your electric bill.

Maybe start a protest by setting up electric heaters in your front yard (against the tiers).

I plan to install myself.
Our county has speed permitting.  It's $160 and the permit is 9 pages.  Planning on doing that myself.
One I have county approval I have to get permission from the power company to operate. Power company has made that quite easy.
I have 3 breaker panels.  Can tie in to any one of them. 

Local code does not require a master discontent at service entrance.
New 2018 building codes changed the setbacks to 18 “in the US.  In the past there was I think a 3-foot setback on all side was required.  I need to verify but I think the new codes allow for 18" on all sides as long as there is one 3 foot set-back on an adjoining roof surface as in across a valley.

 

Offline Nusa

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You're mostly talking about details that are very specific to the country and state that you live in. We can discuss that if you want, but recognize that this forum has a significant international audience, and solar situations around the world may be very different.

However, it happens I'm in California and am somewhat familiar with said rules. My main observation is that rules about net metering are subject to change, and it's quite likely that they will change in coming years. There's certainly enough lobbying going on.

In my opinion, you should justify getting solar solely based on power you can use or store yourself(batteries or thermal) and the resulting reduction in purchases from the grid. Selling power back to the grid should be considered a bonus, but don't count on making much money doing so, long-term.
 

Offline DougSpindler

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If anyone know of an iPad or iPhone solar app to produce estimated yearly production values I would be interested.

PG&E Toolkit (Apple and PG&E customers only.  Logs into your PG&E account, downloads your actual usage and shows you what you are paying every month for electricity.  PG&E has 9 different rate plans for customers and PG&E Tool Kit shows price comparison. 

This one app taught me a lot about how I use electricity and how power companies bill for electricity.
5 Stars from me.  (But unfortunately, the API with the power company is having issues.)  https://itunes.apple.com/us/app/my-pg-e-toolkit/id733009344?mt=8

If there are any App authors out there look at this app for ideas.
Other apps I have tried to use include
SolarMeter (Apple app) looks good but haven’t figured out how to fully use it.
PV Optimizer (Apple apps) Looks good, but not exactly that helpful for designing residential solar.
 

Online mtdoc

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If anyone know of an iPad or iPhone solar app to produce estimated yearly production values I would be interested.

This is better than any App I’m aware of:  PV Watts calculator from the NREL.
 

Offline DougSpindler

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You're mostly talking about details that are very specific to the country and state that you live in. We can discuss that if you want, but recognize that this forum has a significant international audience, and solar situations around the world may be very different.
I understand. 
I thought instead of making this all about me, I would try to make this a bit more general, so it would help others.

Quote
In my opinion, you should justify getting solar solely based on power you can use or store yourself(batteries or thermal) and the resulting reduction in purchases from the grid. Selling power back to the grid should be considered a bonus, but don't count on making much money doing so, long-term.

It is far more cost effective to "sell" the extra electricity to PG&E and get energy credits and buy the power back with those energy credits when the cost of electricity is lower.

One could do the same thing with the battery units without even installing solar panels.  Change when rates are low, and sell to the power company when rates are higher.  Rate plan I'm on I would get a 375% advantage in doing so.

But I learned from Dave battery units are very inefficient.  In charging and discharging the batteries 40% of the electrical energy is lost as heat.
 

Offline DougSpindler

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If anyone know of an iPad or iPhone solar app to produce estimated yearly production values I would be interested.

This is better than any App I’m aware of:  PV Watts calculator from the NREL.

Have you used PV Watts to design a solar system?
 

Offline ez24

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Have you used PV Watts to design a solar system?

Take a look at their other program which seems to take $ into account:

https://sam.nrel.gov/
YouTube and Website Electronic Resources ------>  https://www.eevblog.com/forum/other-blog-specific/a/msg1341166/#msg1341166
 

Online mtdoc

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If anyone know of an iPad or iPhone solar app to produce estimated yearly production values I would be interested.

This is better than any App I’m aware of:  PV Watts calculator from the NREL.
Have you used PV Watts to design a solar system?

I’ve used it to confirm the best orientation and tilt for array installation and I’ve used it to compare the benefits of a one or two axis tracker to a larger fixed array.  The later was a bigger deal when panels were more expensive. Now that panels are cheap, the answer is almost always a bigger array or multiple arrays with different orientations.
 

Offline f4eru

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But I learned from Dave battery units are very inefficient.  In charging and discharging the batteries 40% of the electrical energy is lost as heat.
60% cycle efficiency ? That's very very bad. Is it NiMh ?
Modern Li batteries have 95% cycle efficiency, while lead acid are 85% typically
 

Offline sokoloff

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But I learned from Dave battery units are very inefficient.  In charging and discharging the batteries 40% of the electrical energy is lost as heat.
60% cycle efficiency ? That's very very bad. Is it NiMh ?
Modern Li batteries have 95% cycle efficiency, while lead acid are 85% typically
They don't have 95% efficiency when you consider them as a system (considering charging voltage conversions, coolant pumps, and any other support systems). I'm pretty sure my car charging loses more than 10% on a full-cycle basis.
 

Offline DougSpindler

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But I learned from Dave battery units are very inefficient.  In charging and discharging the batteries 40% of the electrical energy is lost as heat.
60% cycle efficiency ? That's very very bad. Is it NiMh ?
Modern Li batteries have 95% cycle efficiency, while lead acid are 85% typically

Dave talking about lead/'acid storage cells.  Problem with Li and NiMh is the short life span.  Yes they might be more efficient, but they don't seem to last for more than a few years with daily charging/discharging.

 

Offline DougSpindler

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Solar panels, Mono or Poly?
From what I've been reading and what Dave said in his video seems it doesn't seem to mater much.
Not sure that brand name makes a difference either.  Panels for residential use (at this time) produce in the 275 to 325 watt range.

My thinking is to go for "best" price.  Or are there other factors I should be considering.  I'm also thinking these panels are held in with four bolts and have two connection wires if on goes bad it's a simple mater to replace it with another one.  And chances are prices will continue to decrease as production increases so a replacement will cost less and produce more.

I think solar shingles and anything else other than mono or poly are not worth considering at this time.


Inverters, micro-inverters and optimizers
When I first looked at solar I was told to use an inverter.  Then I was told micro-inverters were better.  And now when I ask people I'm being told inverters but add in an optimizer.

My roof is in full sun.  I'm thinking I don't need an optimizer, but then I read in a post optimizers allow for the monitoring if each solar panel instead of the just the entire system.  I would think this would be a plus if I don't have or pay for a monitoring service.

Wiring
My understanding is the the wire guage and type of is different if you use an inverter, micro-inverters and optimizers.  Heve not really found any good informaiotn to figure out what to use.  I'm sure there are advantages and disadvantages for each.  Just not sure what they are.






 

Offline metrologist

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I'm not sure how you're planning to work the numbers in your favor, unless you are able to shift all 27kWh daily use to off peak time.

If you run some numbers on battery cost and lifespan, you will see that batteries can cost as much as a standard electric rate, so you loose with self storage.

I agree with a grid tied system that is optimized for energy production. I believe your area has a solar insolation rating around 5, so you could expect about 1500WHr/day out of a 300W panel.
 

Offline DougSpindler

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I'm not sure how you're planning to work the numbers in your favor, unless you are able to shift all 27kWh daily use to off peak time.

If you run some numbers on battery cost and lifespan, you will see that batteries can cost as much as a standard electric rate, so you loose with self storage.

I agree with a grid tied system that is optimized for energy production. I believe your area has a solar insolation rating around 5, so you could expect about 1500WHr/day out of a 300W panel.

Thanks.  If the  1500WHr/day is correct I need to figure out solar production values to energy credits with the power company.
I'm attaching a typical daily usage report from the PG&E Tookit app for a 24 hr period on a week day.
If you look you will see I use most of my electricity when rates are at $0.12 kWhr.  Durning the day when the power compny will credit me for a kWhr they will "pay" either $0.24 or $0.45 kWhr.  I'm thinking not guessing I since I would accrue so many enegy credits in the summre months when the cost per kWhr is $0.13 higher in the winter I would only need a system which would produce about 5,000 kWhrs per year or about half of the kWhrs I actulay consume every year to (near) zero out my bill with the power compnay.

I beleive you are correct I am in the 5 zone.
Not following your units.   1500WHr/day

Please correct my math if it's incorrect.
If I use 12.000 kHrs in a year would dividing by 1500WHr/day be the number of panels I would need to produce 12,000?  That woudl be 8.  But that doesn't sound right. Or do I need to multiply the 8 buy 5.5 hrs of sun per day which would mean I would need 40 panles?  That doesn't seem right to me either.


 




 

Offline metrologist

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The insolence number is an annual average. It is basically telling you how many hours a panel will produce maximum output. That was 1500WHr per panel per day in your area. I am just considering averages for all your numbers, so 12,000kWHr per year is about 32kWHr/day, and it would take ~21 panels to produce that amount of power (32kWHr/300Wx5). You will have excess in the summer and not enough during the winter.

Since your use is primarily off-peak, setting up for maximum output would be ideal. You might be able to get a little more in the translation if you split your array to favor both morning and evening, but I suspect that producing more during peak sun hours @ mid peak rate would pay more overall than producing less @ peak rate.

BTW, aren't the higher rates you pay ($0.45) because of your use bumping you into a higher tier? I know you said you are on TOU plan, but I did not think PG&E had any base rate that high. I'm also not familiar with PG&E solar energy buyback program, but I would be surprised if they paid that much for residential solar production.
« Last Edit: April 18, 2018, 07:08:55 am by metrologist »
 

Offline woody

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A couple of quick remarks:

- West (or east or worse still, north) facing panels make less electricity than south facing panels in the northern hemisphere. I am not sure how these credits work out where you are but in my country one would be crazy to mount panels west if south was an option.

- Find the kWh/kWp factor for your location. This is based on a panel that faces in the ideal direction, at the ideal elevation that gets the average sun hours for the area. As an example, on my latitude (52 deg.), for a south facing, 35 degree elevated panel that factor is 0.85 kWh/kWp. With this factor you can calculate the total kWp you need. For instance, when I want to generate 6000 kWh I need 6000/0.85 = 7058 kWp. If I use 300Wp panels I would need 7058 / 300 = 24 panels. Factors like dirt (soot/moss/birdshit/leaves/snow), shading, less than ideal placement, inverter efficiency, panel age etc. all negatively influence the output of solar panels.

- Advantages of microinverters: No high DC voltages on your roof. MPPT per panel, so superb compaired to string inverters when shadow is an issue. Better monitoring on a per-panel basis. Supposedly longest life (YMMV). No noisy central inverter that needs to be replaced maybe twice during the life of the panels.

- Disadvantages of microinverters: More expensive. Difficult to replace if one goes down because they are under the panels and on your roof. Slightly lower total efficiency.

- Mono-crystalline panels look better.

- Battery solutions in a grid-connected situation are unaffordable. Last time I did the calculation the price of a saved-and-recovered kWh from a Tesla powerwall was €0,55 cents ex. the cost of the kWh itself. Or nearly three times the price of a kWh straight from the grid. Might be better when the price of a powerwall plummets.
 

Offline DougSpindler

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Since your use is primarily off-peak, setting up for maximum output would be ideal. You might be able to get a little more in the translation if you split your array to favor both morning and evening, but I suspect that producing more during peak sun hours @ mid peak rate would pay more overall than producing less @ peak rate.

BTW, aren't the higher rates you pay ($0.45) because of your use bumping you into a higher tier? I know you said you are on TOU plan, but I did not think PG&E had any base rate that high. I'm also not familiar with PG&E solar energy buyback program, but I would be surprised if they paid that much for residential solar production.

Thanks for explaining.
I think it makes little sense to have any east facing panels.  Power company would only pay $0.12 or $0.24 kWhr.  West facing would pay $0.24 or $0.45 when the sun is at the same angle. 

This whole thing of over producing to earn energy credits in $$$ and then using those credits to buy the electricity back makes this complicated.

BTW, aren't the higher rates you pay ($0.45) because of your use bumping you into a higher tier?  No.

I am on a stright Time of Use, no tiering rate plan.  Every day durning the summer months I have to buy electricy for $0.45.  PG&E has two rate plans like this.
The 7 other 7 rate plans all have tiering.  But only one rate plan (that will be disconituned end of this year) is stright tiering.  The ohter 6 rate plans are all Time of Use with Tiering.  I belive those rate plans in the highest tier are not more than $0.36 kWHr.

I have to thank the folks who wrote the PG&E Toolkit app as it show for the amount of electricy I use how much PG&E would charge me for all 9 rate plans.  Almost every month the rate plan I am on works out to be the most cost effective for me.  The Time of Use Tiered rate plans are always more expensive for me.

PG&E appears to be the leader in complicated rate sturctures for consumers.  I suspect other power companies will follow.  This is only possible with Smartmeters.





 





« Last Edit: April 18, 2018, 02:40:08 pm by DougSpindler »
 

Offline sokoloff

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I think it makes little sense to have any east facing panels.  Power company would only pay $0.12 or $0.24 kWhr.  West facing would pay $0.24 or $0.45 when the sun is at the same angle. 

This whole thing of over producing to earn energy credits in $$$ and then using those credits to buy the electricity back makes this complicated.
You also need to factor in some change risk. You’re installing panels for 25+ years. The sun will keep following the same path in the sky that whole time. The billing and credit arrangements with your local power company are not nearly as stable.
 

Offline KD0CAC John

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I do not think that PG&E or any power company is going to let you buy low & sell high , if there is a chance of doing that , it will change fast .
You must be missing something , thinks that ?
Seems to be similar thinking with facing panels ?
 

Offline DougSpindler

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I do not think that PG&E or any power company is going to let you buy low & sell high , if there is a chance of doing that , it will change fast .
You must be missing something , thinks that ?
Seems to be similar thinking with facing panels ?

Nope.
Found this on PG&E’s web site.

“Monthly statement: Each month, your PG&E Energy Statement shows the amount due for that billing period including monthly minimum delivery charges. The statement also shows a summary of your year-to-date solar charges and credits and how you are tracking towards True-Up.”


Every “solar expert” I’ve talked to tells me the same thing.  There have been four times when the solar guy has called PG&E with me and the PG&E rep tells the solar guy he has it all wrong.  And the solr guy responds by saying the rep doesn’t know what they are saying as in trying to “trick” me.  They also say the web site is wrong.  The video is wrong and the wording in my rate plan contract is wrong too. 

Thinking maybe they might be right, I’ve called PG&E on my own and spoke to other reps, who are well trained and quite knowledgeable all tell me the same thing as what’s in the video. 

All of the solar companies tell me same thing you are saying, that I have it all wrong.  I have called PG&E at least 6 different times.  Every time PG&E tells me the solar guys have it wrong.
I’ts in the rate plan contract Ihave with PG&E.
I’t’s on PG$E’s web site.
And they made a video years ago that say the same thing.

In the video they have example houses.  The third one at about (:40 seconds) is for Time of Use. 
They clearly if you overproduce you can export to the grid rates are higher and use/buy back when prices are lower.  Notice they use the word prices, and not kWhrs.

What they don’t say in the video is if you have any roll over extra energy $$$ credits.  At the end of 12 months you forfeit the all of the energy credits and in some cases PG&E might give you $0.02 on the dollar.


 


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