Estimating future usage and system sizing

[ver2go]

Sorry, got busy with work, family and smaller home projects and frankly, after talking to a few installers I just got so confused that I let go. Can you please PM me the name of your installer? $3 per kW sounds good

+1 on this. I can't get anyone south of $4.xx. Does flat roof add that much more? Some installers are claiming that.

[sjsun]

+1 on this. I can't get anyone south of $4.xx. Does flat roof add that much more? Some installers are claiming that.

No idea about flat roof but looking at quotes I got in February, I can't seem to get anyone below $4.xx either. Have prices fallen significantly since then? Is there a reliable site which I can use as reference for equipment pricing and then workout labor estimates accordingly?

[ver2go]

No idea about flat roof but looking at quotes I got in February, I can't seem to get anyone below $4.xx either. Have prices fallen significantly since then? Is there a reliable site which I can use as reference for equipment pricing and then workout labor estimates accordingly?

What I did was download the entire CSI database. Then started narrowing down in Excel.

For example,
Start with filtering on the local countries. I elected CCC, Alameda, SF, San Mateo
Then selected Sunpowers, since that was what I was looking for.
Then kept playing with filter and finally added a column to do price per watt.

Asked for estimates from there. Of course even all the installers with less than $4/watt in CSI still ended up quoting me way above $4/watt.

I guess I'll have to see what happens after the next election.

[solar pete]

+1 on this. I can't get anyone south of $4.xx. Does flat roof add that much more? Some installers are claiming that.

Howdy ver2go,

Iam in Oz so we have different architecture, BUT yes flat roof are a pita, as a general they do add cost to the install. Sometimes we cant install on them depending how its been made.

[sjsun]

What I did was download the entire CSI database. Then started narrowing down in Excel.

For example,
Start with filtering on the local countries. I elected CCC, Alameda, SF, San Mateo
Then selected Sunpowers, since that was what I was looking for.
Then kept playing with filter and finally added a column to do price per watt.

Asked for estimates from there. Of course even all the installers with less than $4/watt in CSI still ended up quoting me way above $4/watt.

I guess I'll have to see what happens after the next election.

Thanks ver2go. I very eagerly downloaded the CSI data but oddly enough could not find any installs with my panel of choice - LG 300W Neon. Per Watt price also seems to be cheap at the lower end of panels, below 280W. Looks like volumes are still low on the higher efficiency panels? Interestingly, I found one installer that seems very frequent in the CSI data but not reviewed much on Yelp.

[sensij]

Thanks ver2go. I very eagerly downloaded the CSI data but oddly enough could not find any installs with my panel of choice - LG 300W Neon. Per Watt price also seems to be cheap at the lower end of panels, below 280W. Looks like volumes are still low on the higher efficiency panels? Interestingly, I found one installer that seems very frequent in the CSI data but not reviewed much on Yelp.

CSI data came from applications for the CSI rebate. That rebate ended for residential customers in early 2014, before the 300 W LG panels were even released. No data has been collected since then. Most CSI prices are higher than what can be found today, as equipment prices have fallen somewhat since then.

[decaview]

Hi,

I live in the SF Bay Area (peninsula) and shopping for Solar. My current usage averages only about 500kW/month. So first, I am trying to estimate future usage. Right now, we are a young family (me, wife and a toddler) - that will likely grow and we are looking to add at least one EV in the near future and another depending on work/commute situation. For the first EV, I was eying the Mercedes B Class electric since it seems to be the only one with ample room for a small family. It is rated at 40kW/100 miles so with 1000-1200 miles a month of driving, the electricity usage would be ~500kW/month. Also, as kid(s) grow older, the current 500kW residential usage will climb up too. Maybe 700kW? In 3-4 years, with one EV, is 1000-1200kW/month a reasonable estimate of usage? (No pool, AirCon)

So far, I got quotes from Sungevity and Luminalt. Sungevity did not come out to the site yet and based on their remote survey, said maximum they can put up are 21 panels. For a 5.25kW system, they are quoting me ~21k before rebates/tax-incentives. Luminalt quoted me ~$25k for a 5.13kW system with Sunniva 270W panels (19 panels). They also quoted me $28k for a 6.2kW system with 23 panels (Luminalt did a physical site survey and said they can install 23 panels).

My questions are (1) Is my energy usage estimate reasonable? (2) If yes, then does it make sense to go for higher efficiency panels like the SunPower E20 or X21?

With a typical 250/270W panel, I can cover most of my residential usage (keeping me in Tier1 of the rate bands) with solar panels even if my usage goes up to 700/800kW/month.

But even though EV charging is only 10cents/kW right now (PG&E), it can go up depending on PG&E/CPUC policies where it becomes more expensive than Solar energy. At that point, I will pay a lot more to the utility than if I go for an over-sized system now.

Also, what is a rough method to calculate cost per kW generated? Assume 25 year life-span, estimate 1st year energy generation, adjust for panel degradation every year for 25 years and sum up the power generation over 25 years. And divide the total cost sunk into the system with the total power generated over the span of 25 years? (Not taking into account time value of money, inflation etc)

Would really appreciate either specific replies or in general, any replies explaining the larger context around which I should be making a decision.

Thanks

You got to do your meth carefully before investing in a solar system. With PG&E EVA Tariff, you may only need 2.5kw system to cover most of your bill. I just got a quote for 2.5kw system for $9k pre-tax. It is estimated to produce about $75 worth of electricity per month base on EVA Tariff and I use about 600kwh per month and cost me $95 per month.

[wrysys]

any other recommended installers in bay area, pls pm to me

[sjsun]

CSI data came from applications for the CSI rebate. That rebate ended for residential customers in early 2014, before the 300 W LG panels were even released. No data has been collected since then. Most CSI prices are higher than what can be found today, as equipment prices have fallen somewhat since then.

D'oh! Thanks for pointing that out

I got two contractors to come down to $4.2/W installed. One's quoting 315W LG panel and the other has Hanwha 260W panels, a total of 17 panels. Both are including micro-inverters. Plus, $3500 for panel upgrade to 200Amp service.