getting Solar evaluated...need some guidance

[jlatenight]

Sounds like a lot of money. What's it going to cost up front ? Depending on your situation what you describe could be a great deal, but I'd dig into the details and verify. I think I may be seeing some smoke and mirrors. As I suggested, not everyone tells the truth or the whole truth all the time. Trust but verify on your own, especially about (projected) utility rate increases and things like "total positive value" - what is that exactly ? SREC's in there ? Cost of funds ? tax considerations? assumptions ? And how is it calculated ? Many vendors in San Diego shouted about 30% - 40% rate increase last Sept. Published rate tariffs proved that mathematically impossible. A little digging and Socratic questioning showed that most of that was hype, word play or just plain B.S. believed by people all too eager to repeat what they read/hear.

Caveat Emptor.

I'd get more quotes and more education on the subject, and take some time.

BTW : What's TSRF ?

Cost to me is nothing up front. I guess what they mean by "total positive value" is the benefit to me over the life of the system given it's output, it's cost, all the discounts, my annual electrical grid use, etc. Basically everything calculated together. What I'm worried about is if all those 'variables' are a)correct, and b)accounted for. TSRF stands for Total Solar Resource Fraction. It's the ratio of insolation available accounting for both shading and TOF (Tilt Orientation Factor)....I guess it's basically how much sun hits your panels or something like that. Maybe he was "overstating" the rate increases. I can find the 38% increase from Nov, but not the one that supposedly happening to two months. Plus I think the 38% increase stops in April. Boy....this is some confusing stuff.

[Naptown]

Ok, went to PVwatts, assuming I filled it out right, came out to 5963 kwh/yr.... way less than what he said (7120kwh/yr). How accurate is PVwatts?

What was the derate factor that you used?
Default will always come in very low
Average derate is about .83 Default is .77

[slopoke]

Ok, the system he sized is 5880w DC, est. 7120kwh/yr. My TSRF is 80% on average. Panels are 24x245w Trina panels. When it's all said and done, after rebates and incentives, he figures I'd be positive $78.85/mo the first year. Based on today's electricity rates (which by the way are going up 30% in two months, and they just went up 37% in Nov), for the life of the system (25 years, but will most likely be more), I'll have a total positive value of $60,506 The cost of the system is reduced 50% by tax credits, incentives, & rebates. That's good right?

I'm not an accountant, but using your numbers of 1088 kW hours average per month and that comes to paying your POCO $196.00 per month. If your proposed system does produce 7120 kW hours per year/ 593 kW hours per month average. So now your monthly bill is $89.00 for electricity, saving you $107.00 per month, or $1284 per year. I don't agree with the solar company that you will go positive by $78.85 per month.

I'm assuming this is a purchase not a lease. So now take the after incentives cost and divide that by $1284, that will give you how many years to break even. You'll have to figure out how much ROI is right for you. When I did my system, I did not factor in any increases to what my POCO charges because I don't know what the actual increases might be if any. My system should take just under seven years to pay for itself and if there are any increases to our electricity rates, that will just help to break even sooner. For me 7 years to break even is a ok ROI, good luckk.

[pleppik]

Ok, went to PVwatts, assuming I filled it out right, came out to 5963 kwh/yr.... way less than what he said (7120kwh/yr). How accurate is PVwatts?

Probably more accurate than a salesperson.

So this is where the rubber meets the road. I'm not an expert, but the people on this forum who have posted thousands of times will probably say that PVWatts is pretty good for a simple consumer tool. You should be able to get the number from PVWatts to come within a few percent of what the site survey estimates, if the site survey was done correctly.

There are a bunch of different parameters in PVWatts you can tweak, like the shading factor, inverter efficiency, etc. You should ask your salesperson to explain why there's this big discrepancy, and help you understand the parameters he's using to come up with your production estimate.

If he can't give a good reason for any discrepancy, then the 7,120 kwh/year is BS, and not based on your actual site parameters.

Also, when you do get an explanation, pass it along. Lots of people here can help augment your BS detector. It's practically a contact sport in this forum.

[inetdog]

Ok, went to PVwatts, assuming I filled it out right, came out to 5963 kwh/yr.... way less than what he said (7120kwh/yr). How accurate is PVwatts?

PVWatts is very accurate but depends on three assumptions:

1. The insolation is based on historical average weather patterns at one point in the approximate area you look up. Actual and future conditions may vary.
2. PVWatts assumes a standard performance coefficient for the conversion between insolation and the panel output. It is probably low for current high-end equipment, but you can change that number as an input.
3. It assumes that you have an unobstructed horizon to horizon view. Based on that factor, there is nothing that you can do in a specific case to improve that. Except maybe mount the panels at the top of a south-facing cliff.

[jlatenight]

OK, now to go PVWatts and punch in his numbers and see if it comes up with something close for the production.

My gut check is that the production estimate sounds a bit high for a fixed orientation system in MA. You can get that, but the orientation of the array would have to be nearly optimal with no shading. He should have given you the azimuth and elevation of your roof, and the shading factor from the site survey, so you can get an idea if these numbers are realistic.

Also, are you enough of a finance geek to be familiar with the Net Present Value calculation and what it means? If not, then that $60,506 number might as well be from Mars.

Ok, went to PVwatts, assuming I filled it out right, came out to 5963 kwh/yr.... way less than what he said (7120kwh/yr). How accurate is PVwatts?

[J.P.M.]

Ok, the system he sized is 5880w DC, est. 7120kwh/yr. My TSRF is 80% on average. Panels are 24x245w Trina panels. When it's all said and done, after rebates and incentives, he figures I'd be positive $78.85/mo the first year. Based on today's electricity rates (which by the way are going up 30% in two months, and they just went up 37% in Nov), for the life of the system (25 years, but will most likely be more), I'll have a total positive value of $60,506 The cost of the system is reduced 50% by tax credits, incentives, & rebates. That's good right?

Sounds like a lot of money. What's it going to cost up front ? Depending on your situation what you describe could be a great deal, but I'd dig into the details and verify. I think I may be seeing some smoke and mirrors. As I suggested, not everyone tells the truth or the whole truth all the time. Trust but verify on your own, especially about (projected) utility rate increases and things like "total positive value" - what is that exactly ? SREC's in there ? Cost of funds ? tax considerations? assumptions ? And how is it calculated ? Many vendors in San Diego shouted about 30% - 40% rate increase last Sept. Published rate tariffs proved that mathematically impossible. A little digging and Socratic questioning showed that most of that was hype, word play or just plain B.S. believed by people all too eager to repeat what they read/hear.

Caveat Emptor.

I'd get more quotes and more education on the subject, and take some time.

BTW : What's TSRF ?

[pleppik]

Ok, the system he sized is 5880w DC, est. 7120kwh/yr. My TSRF is 80% on average. Panels are 24x245w Trina panels. When it's all said and done, after rebates and incentives, he figures I'd be positive $78.85/mo the first year. Based on today's electricity rates (which by the way are going up 30% in two months, and they just went up 37% in Nov), for the life of the system (25 years, but will most likely be more), I'll have a total positive value of $60,506 The cost of the system is reduced 50% by tax credits, incentives, & rebates. That's good right?

OK, now to go PVWatts and punch in his numbers and see if it comes up with something close for the production.

My gut check is that the production estimate sounds a bit high for a fixed orientation system in MA. You can get that, but the orientation of the array would have to be nearly optimal with no shading. He should have given you the azimuth and elevation of your roof, and the shading factor from the site survey, so you can get an idea if these numbers are realistic.

Also, are you enough of a finance geek to be familiar with the Net Present Value calculation and what it means? If not, then that $60,506 number might as well be from Mars.

[pleppik]

A guy is on my roof taking measurements and assessing its solar potential as we speak. I have a meeting today at 2pm to review his findings. Can you guys come up with a handful of key questions to ask the guy? I guess the main thing to ask besides price is how much wattage the system will generate. What are other questions to ask? Thank's a lot for everyone's help!! -Jon

Ask every dumb question you can think of and try to really understand everything about where his numbers come from.

[jlatenight]

Ok, the system he sized is 5880w DC, est. 7120kwh/yr. My TSRF is 80% on average. Panels are 24x245w Trina panels. When it's all said and done, after rebates and incentives, he figures I'd be positive $78.85/mo the first year. Based on today's electricity rates (which by the way are going up 30% in two months, and they just went up 37% in Nov), for the life of the system (25 years, but will most likely be more), I'll have a total positive value of $60,506 The cost of the system is reduced 50% by tax credits, incentives, & rebates. That's good right?

[peakbagger]

Mass has some very sweet incentives that vary by utility and I believe that Feed in Tariffs are available. One of my coworkers paid out of pocket for a system and maxed out his roof with panels and he figures with the 30% fed rebate, the local incentives and the FITs that his payback is four years and then he earns 5% per year.

[prhamilton]

Sorry, got some threads crossed and thought you were in California.

California is unique in energy pricing(right now) in that we pay 0.13 kWh for our first 300 kWh. Then we 0.16 for our next 150 kWh. Then we pay .33 after that. So with my usage, my effective rate is 0.24 per kWh. Someone who uses less power might see their rate as low as 0.13 and a heavy users might have a rate approaching .33 per kWh. My comment was to try to keep usage in the first tier where the rates are favorable.

Sorry to muddy the waters with California specific stuff. If your rates are a flat 0.16 kWh then it makes the calculations pretty easy. Then you need to figure out what rate they credit you back. I think MA has pretty friendly net metering rules.

[jlatenight]

Thanks for your great replies too, PR. very helpful! Keep in mind I'm in MA, not CA. Here's some info on my power usage: I'm paying $0.18/kwh and I use an average of 1,088kwh/mo. In 2013, the lowest month was May at 672kwh and the highest was Aug at 2113kwh. Can you elaborate a little on this statement:

I would shoot for replacing all but 150 kWh per month with solar, that will leave you right in the middle of tier 1 and give you a fudge factor so you don't over or under produce.

[prhamilton]

The vendor is going to give a pretty detailed sheet with a lot of that information. I have spreadsheet I used that I can share, wanted to look at ROI if the rates didn't go up 3% year, a lot of ROI assume that. I also wanted to see played a discount rate and see how that effected ROI. It might be nice to have all the really knowledgeable people on the forum contribute to a checklist/spreadsheet as a sticky topic. There are some good online tools like pvwatts at NREL that are really helpful too.

Do you know your annual usage from PGE? If you have that and you expect it remain pretty stable for the next 5 years then sizing the system is going to be easy. If your annual usage doesn't have all your conservation then you are going to need to either estimate your new usage or wait a year. I would shoot for replacing all but 150 kWh per month with solar, that will leave you right in the middle of tier 1 and give you a fudge factor so you don't over or under produce.

I will say that it is a good time to be considering solar in CA. You can read up on net-metering and the upcoming changes from AB327(this is a good summary ab327 Factsheet). The take away for me is that CA net metering(NEM) is a good deal for solar as it stands right now. AB327 dictates changes to the program for 2017. In the next two weeks California Public Utilities Commision is going to release the transition plan to the new net metering rate structure. They are widely expected to grandfather in existing solar systems for 10-20 years, the decision is due March 31st. The uncertainy can make ROI calculation and future savings difficult to analyze.

Add to that the federal tax credit ends in 2016 and you can see you are in a bit of sweet spot right now. I am concerned that once people in California start to realize that they need to get installed by X date to get grandfathered in to the current net metering pricing there is going to be a lot more installs and prices will creep up.

Long story short, I would get several bids. You can get them very quickly online. I got 5 bids, 4 of them online in little more than an hour. I spoke with Solar City, Real Good Solar, Sungevity and The Solar Co. I also got a quote from a local installer. I recommend getting quotes from at least one 'big vendor' and one 'local installer'. The big vendors all had the same feel to me but the local installer was very different. Local guys was low pressure and easy going, big guys more salesman-y and had high prices that would magically come down(like buying a car, let me check with my manager). Best thing you can do is tell them you are getting 5 different quotes.

Also I found this forum to be invaluable, I'd say you are definitely on the right track.

[J.P.M.]

Thanks for the reply JPM. I've had my house assessed for energy efficiency and based on that I added a second layer of insulation in the attic, CFL's, sealed-up all gaps, weather stripping, etc. I have energy efficient appliances. It just seems like trying to understand the whole solar thing is very complicated. Lots of differing opinions, tons of variables, everyone's situation is different, etc. I wish someone could make a fill-in-the-blank worksheet with all the critical info; how much energy I use, the cost of my electricity, and the details from the solar eval I'm getting (size of potential system, output, etc) with the cost and terms of the system to tell me whether it's worth it or not. Does something like that exist?

You're Welcome. I suppose sometimes folks think I'm an arrogant SOB, probably w/ some justification. No offense intended.

FWIW, such checklists probably do exist. I doubt they don't do as much harm as good in many situations partly by leading hapless consumers into thinking they are solving all their problems with the wave of a piece of paper, not to mention that such tactics may conveniently sidestep the issue of perhaps not doing solar at all which in many cases is the most cost effective decision, contrary to what subjective opinions may hold. Every situation is different although there are usually many similarities among users. I do not believe there is a better way than deciding what you want to accomplish, doing your own research and adjusting goals as you learn more.

Learn & understand how you are charged for electricity. This is a PITA but very worth the effort.

The best observation I've had about this is to question everything everyone says and try like hell to know the answers to your questions before you ask. Do your own homework. You'll learn more, be better informed and hopefully get B.S.'d less or at least be better able to smell it when it comes out of a peddler's mouth. Not everyone who tells you what you want to hear is your friend. Not everyone who tells you what you don't want to hear is your enemy.

Choose your vendor carefully. This is probably at least as important as buying good equipment. If solar is your choice, a good vendor is the key to a successful installation from start and several years down the road. I chose bidders who have been in business for a long time as elec. contractors and have reputation. They usually know how to run a project, deal w/ inspections, meet a payroll and know the value of customer relations, among other things.

On Price : it's bad to pay too much, but worse to pay too little. Buy cheap - buy twice. Good vendors are worth a premium - just how much is your call. Competitive bids help this some.

The salesperson's goal is to leave your home with an order for goods and services. Don't be rushed. A good deal today will still be good next week. Caveat Emptor.