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**J.P.M.** · 08-31-2018, 10:49 AM

1.FIRST: Never apologize for unintentional ignorance which is no more than something you don't know yet. That's unnecessary B.S. But so is not doing your own homework and expecting to be spoon fed answers and not doing things you could just as well at least start doing for yourself.
2.) And this is VERY important - homework time - look at how PG & E handles system expansions under NEM. I'm pretty sure you'll find that they want to know what your planning to do. After you check the NEM rules on your own, call PG & E and confirm what you've read.
2.) Determine how much extra power you want to produce - get a number in kWh/yr. Start there. If it's 100 % of new use, fine, but know how much in kWh/yr. over current year's usage you want as a goal.
3.) Why such different size systems ? If you read as much here as you say, you'll surely have read that decent systems produce about the same annual output/STC kW. Shading aside for a minute (only), if anyone's 4.32 kW system will meet your (added) requirements, so will anyone else's 4.32 kW system. So why a 20 % larger REC system ? Either S.P. is undersizing (which will never happen), or they are working to different added loads (see #2 above) or the REC dealer is dancing with your leg. Non S.P. systems will require about 20 % more AREA (not 20% more installed capacity) for the same system size of, say, ~ 4.32 STC kW. A non S.P., say, 4.2 STC kW system may take some additional area, so put as much of it in the non shaded area as possible. You'll still be $$ ahead over the S.P. unnecessary $/ STC W premium, particularly when you realize you won't need a larger (electrical) size non S.P system and can therefore probably make a not S.P. system less than that 5.22 STC kW system the REC peddler was going to foist on you.

Bottom line(s): Get informed, get the added load(s) right, get the system electrical size right by using PVWatts, avoid S.P. for the excessive price, and stay out of the shade as much as possible.

AND, MOST important : Get correct information about NEM from the CPUC and published stuff from PG & E and then CALL PG & E after you get knowledgeable. Basically, try very hard to know the answers to the questions you'll be asking before you ask those questions. You'll get a bonus education by learning a bit about what people you talk with don't know, particularly vendors. Such knowledge helps with decision making.

Know too, that there seems to be some quality/reliability questions about S.P. and their new, super dooper micro systems. See prior and fairly recent posts on this forum.

Also important : I'd also check the IRS rulings and published stuff about whether or not a residence can get an additional tax credit for what sounds like may/might be considered a second PV system. I'd not expect a vendor to be forthcoming with that information if they thought it would make it harder to close a sale. Do not rely on people with skin in the game to give you any honest information in these matters.

Welcome to the neighborhood and to the forum of few(er) illusions.

Take what you may want of the above. Scrap the rest.

**azdave** · 08-31-2018, 11:01 AM

I gave you my comments already on the other non-solar forum we belong to where you posted these questions. Welcome and let's see what others have to say about your options. Many members here are wayyyy more experienced than I.

**scdaren** · 08-31-2018, 11:55 AM

Thank you JPM.

-- I know PGE requires me to go to TOU rates. Basically, this solar company is going to avoid that by not telling PGE about the new panels. I think this is probably shady at best, illegal at worst, so even if I go with them, I will have them do it above board with respect to PGE and lose my grandfathered rate plan. PGE has an analysis tool online that says I would have paid $200 more on my last true-up if I had been on the TOU plan, but that does not account for any changes in habits we would make to reduce peak use, so I think it's not a huge deal.

-- So figuring out my use is a bit tricky. I have a new pool, with a heat pump. The pool pump is not too hard to estimate because I know the power use and number of hours I'll need to run it per day. However, the heat pump is another story. It uses MUCH more power, and my use from it comes from how much I heat the pool -- I don't really know yet what that number will be. My usage for the past 12 months was 5767 kwh, and both quotes targeted 100% of that use (how they came up with such different sizes, I don't know, I'm going to follow your advice and work on the PVWatts). But only the May-Aug portion of that 5767 number includes the pool pump and heat pump use. I'll be running that pump hard in April, September, and maybe into October, and of course the pool pump year round. My best guess is that my annual use will end up somewhere around 8000 kwh. I don't think PGE will allow me to put on a system that's 138% of my 12 month running use, and I don't know I can fit or want that may more panels on my roof anyway. So at this point I'm thinking bigger is better (and admittedly I already have that mindset kind of buit-in from regretting not going bigger originally).

-- With regard to IRS, I have read their publications, and I don't see anything about not being able to take the tax credit again. If anyone knows otherwise, please let me know.

And thanks for your input azdave!

**J.P.M.** · 08-31-2018, 12:32 PM

You are welcome. Thank you for not acting like a whining, petulant child as is common around here.

What's your zip ? You've got a 6.4 STC kW system for ~ 5, 800 kWh/yr. use. Even with E-W orientation, unless you've got a lot of boatload of shading on that array, and if you are in No. CA, I've gotta' believe you're WAY oversized for your current stated electrical load. What does your PG & E bill say about something called excess generation ?

On not notifying the POCO, you'll get caught, first by the POCO and then the AHJ if you do not ensure the vendor notifies them. You'll go off tiered rates at some point anyway, as we all probably will, but not keeping proper authority or the POCO informed of your intentions is a fool's game. It will not come to a good end. You could also potentially run into legal hassles and the loss of NEM or such like. Being proactive in such matters works out better.

Know that it's YOUR responsibility to notify the POCO about system changes, NOT the vendor's.

Also, and to repeat, check with the IRS on eligibility for tax credit for the second of two systems.

If you have natural gas available, and assuming from your posts that you are heating pool water with a heat pump, my question might be, why a heat pump ? Or did heat pump peddler tell you it was cheaper than nat. gas ? One other question, do you have and use an effective pool cover. If not, and if you get an effective pool cover - and use it - you can probably reduce the pool heating load by something like half over not using a pool cover. Just sayin'. As for pool heating load, hard to say. That's dependent on many variables like temp. diff pool H2O to air temp. A big part of the heating load comes from wind and also from something called the dew point temp. Read up. Google is your friend. Just remember that rules of thumb, particularly for pool heating are better for measuring thumbs than heat loads.

FWIW, and NOMB, but I'd consider a good and usable pool cover. I'd also have considered solar pool water collectors after the pool cover way before a heat pump system.

**scdaren** · 08-31-2018, 12:56 PM

Thanks. Those use numbers are for our power consumption after accounting for the generation of our current system -- in other words, our true-up bill. I'm generating and using an additional ~8400 kwh a year on the current system. Zip code is 93619. I actually just checked that system against PVWatts, and looks like it is performing exactly as it should be

With regard to heat pump vs. gas -- I have not done the math myself, but it seems to be fairly widely accepted around here that given our electric and gas prices, the heat pump is the most efficient solution, especially for those with solar. People going gas generally either have an attached hot tub they need to heat, or want to heat year-round. The heat pump only works with ambient temps above 55 F. My pool builder is a good friend of mine and had no financial incentive to go either way. Roughly, I can increase 1 degree F per hour with the heat pump, running at around 6 kw, so 6 kwh per degree increase. One of the things I underestimated going in is the amount of shade from some southside trees in my neighbors yard, already in August shading quite a bit of the pool, and we are already running the heat. But all that aside, one of the biggest variables is how often we decide to swim. If we are busy doing other things a few weekends in September and not heating the pool those weekends makes a huge difference, and that could change year to year. Bottom line, raising the temp to bathwater for a weekend costs me somewhere around $30-40 at the most. It's cheap entertainment vs spending our time at the movies, or going somewhere else with the kids. We have found that our costs for eating out, weekend trips out of town to get out of the heat, and other activities have dropped substantially now that we have a pool and spend more time at home.

A cover definitely would help, and would allow us to keep it warm full time instead of just on weekends. But I do not have a very big yard, and between the space a cover would take up, and the hassle of dealing with it, I just don't want one.

**w00dy** · 08-31-2018, 01:37 PM

I wonder if you could look at moving some or all of the east panels to the west side roof? You could also add a panel or two (the 10% allowed) as an upgrade at the same time - you could then switch to the latest TOU plan with PG&E to keep you on NEM 1.0.

With regards to the pool, the filter pump could be run all off-peak and the heat pump could also run off-peak - which would help you maximize your peak generating time with a more west facing array...might be easier than an entirely new system. I am not sure PG&E's rate calculator will really do good comparisons related to TOU and generation potential - so you aren't getting a true picture of how well a better facing system will perform.

**scdaren** · 08-31-2018, 02:00 PM

Originally posted by w00dy

I wonder if you could look at moving some or all of the east panels to the west side roof? You could also add a panel or two (the 10% allowed) as an upgrade at the same time - you could then switch to the latest TOU plan with PG&E to keep you on NEM 1.0.

With regards to the pool, the filter pump could be run all off-peak and the heat pump could also run off-peak - which would help you maximize your peak generating time with a more west facing array...might be easier than an entirely new system. I am not sure PG&E's rate calculator will really do good comparisons related to TOU and generation potential - so you aren't getting a true picture of how well a better facing system will perform.

The panels we are adding west facing seems better because of TOU. The only issue is that I get some shading on the west side. It takes a bit of guesswork to figure out if the shading will cancel out the TOU benefit on the west side, and it would probably change with the time of year. Also TOU peak is weekdays 4 pm to 9 pm, May to October, so it's not exactly prime generating hours anyway. On 2 out of 7 days a week I am better off on the unshaded east side since there is no TOU advantage on weekends. Probably my best bet is to put as many as I can on the west side, while trying to avoid the triangle of shade from the peak of my neighbors roof, then the rest on east. With that plan, the higher-powered, more expensive SP panels have an advantage, because I can fit more on the unshaded west area.

I definitely plan to run the pool equipment off peak. Getting my wife to not do laundry during her favorite laundry-doing hours though may be more difficult

**w00dy** · 08-31-2018, 02:06 PM

Originally posted by scdaren

I definitely plan to run the pool equipment off peak. Getting my wife to not do laundry during her favorite laundry-doing hours though may be more difficult

I fight the same battle on TOU - I have resorted to dropping my stuff in the washer on my way to work as it means it gets cycled through and finished earlier in the morning or after dinner when I remember to put it in the dryer...

We have a gas dryer so I don't think it burns too much actual electricity running it at peak time.

**J.P.M.** · 08-31-2018, 02:22 PM

Originally posted by scdaren

Thanks. Those use numbers are for our power consumption after accounting for the generation of our current system -- in other words, our true-up bill. I'm generating and using an additional ~8400 kwh a year on the current system. Zip code is 93619. I actually just checked that system against PVWatts, and looks like it is performing exactly as it should be

With regard to heat pump vs. gas -- I have not done the math myself, but it seems to be fairly widely accepted around here that given our electric and gas prices, the heat pump is the most efficient solution, especially for those with solar. People going gas generally either have an attached hot tub they need to heat, or want to heat year-round. The heat pump only works with ambient temps above 55 F. My pool builder is a good friend of mine and had no financial incentive to go either way. Roughly, I can increase 1 degree F per hour with the heat pump, running at around 6 kw, so 6 kwh per degree increase. One of the things I underestimated going in is the amount of shade from some southside trees in my neighbors yard, already in August shading quite a bit of the pool, and we are already running the heat. But all that aside, one of the biggest variables is how often we decide to swim. If we are busy doing other things a few weekends in September and not heating the pool those weekends makes a huge difference, and that could change year to year. Bottom line, raising the temp to bathwater for a weekend costs me somewhere around $30-40 at the most. It's cheap entertainment vs spending our time at the movies, or going somewhere else with the kids. We have found that our costs for eating out, weekend trips out of town to get out of the heat, and other activities have dropped substantially now that we have a pool and spend more time at home.

A cover definitely would help, and would allow us to keep it warm full time instead of just on weekends. But I do not have a very big yard, and between the space a cover would take up, and the hassle of dealing with it, I just don't want one.

So your total annual electrical usage is ~ 8,400 kWh/yr. + 5,800 kWh/yr = ~ 14,200 kWh/yr. ? Just trying to understand.

On the cover, makes no difference to me whether you have one or not, but know it can cut the pool heat load ~ in half if used. A cover BTW, will usually mean the water temp. is, on average, warmer, particularly after periods of no use, making the time to swimmable temps. after such non use probably shorter. Just sayin'.

Usually, pool heaters are sized to maintain a water temp. based on pool heat loss rate(s) which are mostly f(environment variables, cover/no cover) and not the rate at which the pool water temp. can be raised. A cover BTW will usually mean the water temp. is, on average warmer, particularly after periods of no use, making the time to swimmable temps. probably shorter.

As for space, ease of use and convenience, I had a motorized cover when I lived in Albuquerque. The cover was dark brown, well fitted and doubled as a solar pool heater. I had a nat. gas heater but it almost never fired. The H2O stayed 85 F. or above from early April through late Oct. or so. Summers tend to be warm. Winters and shoulder seasons tend to be mild, but frosys are not uncommon. The cover system came with the pool and house and wasn't cheap, but not as costly as a heat pump. The dark Brown cover was my contribution.

Ever live with a pool before ?

**scdaren** · 08-31-2018, 03:09 PM

Originally posted by J.P.M.

So your total annual electrical usage is ~ 8,400 kWh/yr. + 5,800 kWh/yr = ~ 14,200 kWh/yr. ? Just trying to understand.

On the cover, makes no difference to me whether you have one or not, but know it can cut the pool heat load ~ in half if used. A cover BTW, will usually mean the water temp. is, on average, warmer, particularly after periods of no use, making the time to swimmable temps. after such non use probably shorter. Just sayin'.

Usually, pool heaters are sized to maintain a water temp. based on pool heat loss rate(s) which are mostly f(environment variables, cover/no cover) and not the rate at which the pool water temp. can be raised. A cover BTW will usually mean the water temp. is, on average warmer, particularly after periods of no use, making the time to swimmable temps. probably shorter.

As for space, ease of use and convenience, I had a motorized cover when I lived in Albuquerque. The cover was dark brown, well fitted and doubled as a solar pool heater. I had a nat. gas heater but it almost never fired. The H2O stayed 85 F. or above from early April through late Oct. or so. Summers tend to be warm. Winters and shoulder seasons tend to be mild, but frosys are not uncommon. The cover system came with the pool and house and wasn't cheap, but not as costly as a heat pump. The dark Brown cover was my contribution.

Ever live with a pool before ?

Right, total annual use around 14,000 kwh, probably soon to be around 16,000 kwh.

I completely agree with you on all the benefits of a pool cover. My dad has one on his pool, he has the same heat pump I do, but a bigger pool. He keeps his pool at like 90 degrees, and says the pump doesn't run that often. My pool is freeform and not designed for an automated cover. If I put one on it would sit on a big giant spool at the end of my pool and would be unsightly and very much in the way, with nowhere to put it when not in use. I completely get all the benefits, I just don't like the drawbacks of having a cover, both for space and aesthetics. For me, I'd just rather pay the power costs than have a big cover in my yard and on my pool. There are some smaller foldable covers that you can put on the pool and they float around for partial coverage. Not sure how well they work, but I may do something like that, just haven't got around to looking into it yet.

Heater is maybe oversized, we put on the biggest they sell, and it has a chiller mode too for when the water gets too warm. The big unit did not cost that much more than the smaller one, and heats the water faster, which is a big benefit for us. It was actually kind of an afterthought during our pool build that we added at the last minute. We second-guessed it at the time primarily because of the space it takes up and also the $5k it added to our build cost, but I am SO happy we have it. It's been working great, and makes night swimming so much more pleasant. Gas would have been cheaper up front, but cost more to heat in the long run. In any event, the debate is moot because we have the heat pump, and would make zero sense to replace it. But I don't think I would do any different had I to do it again.

This is our first pool.

**J.P.M.** · 08-31-2018, 03:31 PM

Originally posted by scdaren

Right, total annual use around 14,000 kwh, probably soon to be around 16,000 kwh.

I completely agree with you on all the benefits of a pool cover. My dad has one on his pool, he has the same heat pump I do, but a bigger pool. He keeps his pool at like 90 degrees, and says the pump doesn't run that often. My pool is freeform and not designed for an automated cover. If I put one on it would sit on a big giant spool at the end of my pool and would be unsightly and very much in the way, with nowhere to put it when not in use. I completely get all the benefits, I just don't like the drawbacks of having a cover, both for space and aesthetics. For me, I'd just rather pay the power costs than have a big cover in my yard and on my pool. There are some smaller foldable covers that you can put on the pool and they float around for partial coverage. Not sure how well they work, but I may do something like that, just haven't got around to looking into it yet.

Heater is maybe oversized, we put on the biggest they sell, and it has a chiller mode too for when the water gets too warm. The big unit did not cost that much more than the smaller one, and heats the water faster, which is a big benefit for us. It was actually kind of an afterthought during our pool build that we added at the last minute. We second-guessed it at the time primarily because of the space it takes up and also the $5k it added to our build cost, but I am SO happy we have it. It's been working great, and makes night swimming so much more pleasant. Gas would have been cheaper up front, but cost more to heat in the long run. In any event, the debate is moot because we have the heat pump, and would make zero sense to replace it. But I don't think I would do any different had I to do it again.

This is our first pool.

Thank you.

**scdaren** · 09-05-2018, 11:32 AM

I got a third quote from the company my parents used. Came in at $2.75 a watt for a 5 kw system with Canadian Solar panels and Solaredge inverter and optimizers. Sold!

**J.P.M.** · 09-05-2018, 03:17 PM

Originally posted by scdaren

I got a third quote from the company my parents used. Came in at $2.75 a watt for a 5 kw system with Canadian Solar panels and Solaredge inverter and optimizers. Sold!

Buying on low initial price is a goal of a fool. Look for most long term bang for the buck, particularly through the quality, reputation and longevity of the installer. Buy cheap, but twice. Low buck vendors - the Larry with a ladder types without a long business record can and will screw you in ways you can't begin too fathom. How long has your parent's array been up/running ?

**scdaren** · 09-05-2018, 04:07 PM

Originally posted by J.P.M.

Buying on low initial price is a goal of a fool. Look for most long term bang for the buck, particularly through the quality, reputation and longevity of the installer. Buy cheap, but twice. Low buck vendors - the Larry with a ladder types without a long business record can and will screw you in ways you can't begin too fathom. How long has your parent's array been up/running ?

Haha.. the guy's name is actually Larry! They have had their system for about 4 years, and it is a well known local provider that has been around for about 10 years.

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