CSI EPBB Calculator Question

[silversaver]

Of course theses parameters are good - they are for the SunPower panel. They were an example only of important points that can be very, very different.

Hi Russ,

Base on your experience, how much higher production will a SunPower yield than other makes?

[russ]

The Power Temp Coef (Pmpp) - 0.30% is pretty low compare with other makes @ 0.4% to 0.45%. SunPower has super 25 years warranty and others only 10 years.

Since SunPower offering 25 years, so you will get your panels covered since no way you can match SunPower panels with other makes if panels were bad. On the other hand, most of the 60 or 72 cell panels can be replace with other makes if needed.

Of course theses parameters are good - they are for the SunPower panel. They were an example only of important points that can be very, very different.

[albert436]

Good point that you guys make, I hadn't thought about the 30% thing expiring.

[silversaver]

I think if the expansion is imminent within a year or two at the most, then oversizing may make sense if your POCO allows oversizing. If much longer, it make not make too much sense because the parts may become cheaper in a few years. But then again, we also don't know if the 30% tax credit incentive will be renewed after 2016 or not, which is only 2 years away now. So that also needs to be taken into consideration.

Regarding oversizing now to save on repeat cost of permits and fees, Naptown has shared with us some good info about the cost, and it looks like the structural study and drawing cost is the lion share of it ($1200-$1500) out of $1700 total. But I really wonder if a structural study is required in all cases or not. I really doubt that one was done for my installation because I didn't see any evidence of it, while I see all evidence of all other kinds of paperwork. Maybe there's some easy criteria that determines whether a structural study is required or not, and in most cases, it's not for a normal home roof top.

Agree. It just I rather do it now than later since it takes so much time from shopping to approval to turn on. Yes, 30% Fed incentive is another factor. Expanding a smaller solar system is high per Watt cost and solar system will probably last longer than your roof

[silversaver]

Really true in most cases. You should look for (these datas are from Sunpower panels) -

1) Power Tolerance +5/–0% +5/–0% - many will have a negative tolerance - plan on the output being closer to the minimum than the max.
2) Power Temp Coef. (Pmpp) –0.30% / oC - some have a significantly higher loss of production when hot and your roof will be hot

3) UL listed or equivalent

4) Warranty terms and length - is a 3rd party guaranteeing the warranty in the event the manufacturer goes under?

Others can add as they wish.

The Power Temp Coef (Pmpp) - 0.30% is pretty low compare with other makes @ 0.4% to 0.45%. SunPower has super 25 years warranty and others only 10 years.

Since SunPower offering 25 years, so you will get your panels covered since no way you can match SunPower panels with other makes if panels were bad. On the other hand, most of the 60 or 72 cell panels can be replace with other makes if needed.

[Volusiano]

"Oversizing" seems to be a subject about which people are passionate on this site, with most people dead set against it.

I think if the expansion is imminent within a year or two at the most, then oversizing may make sense if your POCO allows oversizing. If much longer, it make not make too much sense because the parts may become cheaper in a few years. But then again, we also don't know if the 30% tax credit incentive will be renewed after 2016 or not, which is only 2 years away now. So that also needs to be taken into consideration.

Regarding oversizing now to save on repeat cost of permits and fees, Naptown has shared with us some good info about the cost, and it looks like the structural study and drawing cost is the lion share of it ($1200-$1500) out of $1700 total. But I really wonder if a structural study is required in all cases or not. I really doubt that one was done for my installation because I didn't see any evidence of it, while I see all evidence of all other kinds of paperwork. Maybe there's some easy criteria that determines whether a structural study is required or not, and in most cases, it's not for a normal home roof top.

[russ]

[QUOTE=silversaver;98143After months of reseach, I don't think any panel were superior than others, unless limited roof spacing, [/QUOTE]

Really true in most cases. You should look for (these datas are from Sunpower panels) -

1) Power Tolerance +5/–0% +5/–0% - many will have a negative tolerance - plan on the output being closer to the minimum than the max.
2) Power Temp Coef. (Pmpp) –0.30% / oC - some have a significantly higher loss of production when hot and your roof will be hot

3) UL listed or equivalent

4) Warranty terms and length - is a 3rd party guaranteeing the warranty in the event the manufacturer goes under?

Others can add as they wish.

Russ

[albert436]

Thanks for that, Silver. My thought process is similar to yours -- eg. possibly an electric car in the future. The tenant in my rear unit recently bought a Volt which he can charge at work for free. My mom's house is around 2700sf and with 4BR 3BA and is suitable for a family. Who knows who might live there in the future.

"Oversizing" seems to be a subject about which people are passionate on this site, with most people dead set against it.

Most of us are here to learn and I suppose a good healthy discussion will promote that.

[silversaver]

Those are great results.

The installers I've contacted so far seem to have their favorite panels, ranging from 245 to 270W per panel. I'm not sure how the distribution works -- it seems like some installers are more flexible than others on the panels. What was your experience on that? Did they offer you the Bosch or did you find them yourself?

In any case, you really made out with that crazy low price.

I had an early flurry of activity but have been super busy the last several days and have just let things rest for the most part.

They offer me the Bosch. After months of reseach, I don't think any panel were superior than others, unless limited roof spacing, you probably want to go SunPower or LG300. I think Canadian Solar were good choice at lower end price. Cheaper the cost, better the solar value after all. Some vendors do not offer micro inverters and fewer panels to pick. There are few good installers in SD/OC area offering American panel Suniva at about $3.5/Watt range or less. Competition always result in more affordable pricing. Plan your system that fits your life style. EV car will be a trend for most of people here in Socal within next 10 years. Solar system are good for at least 25 years. I will not suggest anyone to build a system just to keep yourself out of higher tier which I think that's a big no no. (unless you are retired and there will not be any extra demand) You don't want to go through the same process again shopping for solar.

2014 is still new, keep shopping among good installers. I have seen SMX panels + SMA @ $3.2 per Watts

[albert436]

Those are great results.

The installers I've contacted so far seem to have their favorite panels, ranging from 245 to 270W per panel. I'm not sure how the distribution works -- it seems like some installers are more flexible than others on the panels. What was your experience on that? Did they offer you the Bosch or did you find them yourself?

In any case, you really made out with that crazy low price.

I had an early flurry of activity but have been super busy the last several days and have just let things rest for the most part.

[silversaver]

What a great discussion, thanks Nap for that analysis, it is really interesting.

Silver, are you saying that your est and actual for Jan were pretty close? I didn't take the time to add up all the numbers from the individual days, does your meter give you a reading for that?

Just curious to know as I am still in the planning stage, and in East SD County which I believe has weather similar to yours.

Thanks!

[ATTACH=CONFIG]3697[/ATTACH]

The Jan 2014 production is on the screenshoot about 633 kWh. Approx. 100 kWh higher than estimate. Everything has reason behind it. My arrays are facing SW245, they are producing less comparing with smaller system facing S180 deg. My inverter is a SMA 6000TL with 98.5% eff compare with others @ between 96 to 97%. Besides that, there are more factors involved with solar output. I'm using a SunPower 30 X225W @6.75kW SW220 deg to referrence with my Bosch 6.63kW, both systems generated very similar outputs unless with cloudy days which no way you can compare the result unless they are next to each other. My solar were new, so I'm just making sure they are operate normally since they are discountined panels. The results were great, so I'm good. I know my installer is good, and I certainly will not complain about the $2.84 per DC Watt cost before inventive because my ROI is less than 7 years. I have few links of SP monitoring as reference, I can pm you if you like. What panels are you gonna pick?

[albert436]

What a great discussion, thanks Nap for that analysis, it is really interesting.

Silver, are you saying that your est and actual for Jan were pretty close? I didn't take the time to add up all the numbers from the individual days, does your meter give you a reading for that?

Just curious to know as I am still in the planning stage, and in East SD County which I believe has weather similar to yours.

Thanks!

sun2.gif

[J.P.M.]

Ok, this is the last time I'll talk about this. Estimate is just an estimate. Please feel free to take a look of each screenshoot, and I hope you have a better idea what I'm say. They aren't really much different. Our vendor (bando and I) hasn't over sizing our systems. I know you don't like them, but please let it go....

FWIW, I like them so much I asked them to quote me a system. One of the four RFQ's that left here went to them. Reputable contractors and IMO, part of the cream of the crop, as were the other 3. Respectfully, you have no idea of what I like or don't like.

[silversaver]

At the risk of breaking my word, I was looking at your Jan. stuff while composing a different rant 1-2 days ago to Bando and noticed how much your Jan. data overshot the est. like hers did, for what I believe is a month that I measured, in spite of what my gut, perception and sensibilities all tell me, as being not that much sunnier than normal. Can you post or P.M. the monthly data you have so far ? I'll ask the same of Bando if she ever talks to me again.

Ok, this is the last time I'll talk about this. Estimate is just an estimate. Please feel free to take a look of each screenshoot, and I hope you have a better idea what I'm say. They aren't really much different. Our vendor (bando and I) hasn't over sizing our systems. I know you don't like them, but please let it go....

[Naptown]

Thanks for the detailed cost layout, Naptown. It looks like the biggest part of the cost would be a structural engineering and drawing plan for $1200-$1500. I'm not sure if my installer ever did one. All I saw was a layout of where the panels go on the roof and where the inverters and boxes will be placed on the house. I also saw an electrical schematic drawn up for the system. But there was no paperwork seen for a structural drawing plan and nobody mentioned to me about having a structural study done on my house. So how do I know whether they spent the money on doing a structural study on my house or not?

Also, if this is an expansion of an already existing design, can't they reuse the original structural study (if they ever did one)? It doesn't make sense that this would have to be done twice. The structure of the house hasn't changed from before afterall, except for the original panels on the roof that were already approved anyway.

Good point about the structural part. It may or may not be needed. However it is my experience with engineers that they will look at the addition as closely as the original and charge the same for the wet stamped drawings. Keep in mind that their license is on the line therefore the same due diligence is required. And this requirement is becoming universal among jurisdictions