n00b

Z714X4

Hi everyone, great forum...especially for us new people! I've been lurking for two weeks now and am starting to understand more and more.

A couple of questions...

I see people talking about how much they paid per watt for their solar system or the average price per watt.

Is that based on DC or AC watts, and is that the rated/listed wattage or the PTC wattage?

(Or is this like politics and I get to choose which ever one I want that fits my present situation 8))

I have roof angles at South/West, more West-South/West, and South/East. I would really like to have my panels flat on the roof and want to know how much production I might be loosing by keeping flat or how much I might gain by tilting them. I'm familiar with PVWATTS but still need my roof angles.

Is there a website that can help me calculate my roof angles?

Thanks in advance!
Aaron

BB.

Re: n00b

First question--On Grid (Grid tied), Off Grid (battery based system), or Hybrid (GT when utility is up, off grid when utility has failed).

In general, the ~$5 per watt is for Grid Tied (no backup power available) is in major metro areas with lots of competition. A 5,000 watt solar array GT system may cost around $25,000 installed (including permits, etc.). This is just a starting point. each installation is different, so you will need quotes. That is before rebates (usually). And "it depends" on the DC panel vs AC watt ratings... In California, the permits, rebates, and "numbers" are usually based on PTC ratings (more realistic numbers which are around 77% to 80% of the DC panel ratings).

Also, although I am not a fan of lease or lease to own, there have been so many tax advantages (to the installer/leasing company) that it has just about pushed the retail installers out of the business in our area.

If you are looking for emergency backup power and/or pure off grid... It will cost a lot more--Probably on the order of $10 to $20 per watt (DIY vs turnkey, hardware chosen, size of system, etc.).

I am not in the solar business--So these are just starting numbers to give you a feel of what your system will be. The actual costs will depend on the design and who does the work and where you buy components.

PV Watts is very easy to predict the output of a solar power system... Use 0.77 derating for a grid tied system (or hybrid). And 0.52 derating for an off grid system (or hybrid system running off grid).

And, this is sort of starting "backwards"... We suggest measuring/understanding your loads, and then doing extreme conservation first. It is almost always cheaper to conserve power than to generate power. If you have never done conservation on your home--It is not impossible to save 50% of the electric bill with just conservation (and energy star appliances, changing from desk top to laptop computers, lots of insulation, new heat pump HVAC/Hot water systems, etc.) measures.

-Bill

Z714X4

Re: n00b

Thanks Bill,

I have a family of 5 living in a 3050 sq ft, 2 story home in the upper desert, Southern California.
Already installed my variable speed pool pump... wow, what a difference that made! I got a rebate on that one too!
CFL bulbs (and a few LED's) throughout and even though we have programmable thermostats, we typically do not run heat or A/C unless absolutely necessary.

Grid Tied system, purchase only, evaluated as needing a 7kW (DC) system from three company's.
I've received 3 quotes for PV that I considered.

1) 28- REC 250W panels, 1- Fronius IQ inverter.
2) 28- Canadian Solar 250W panels, 28- Enphase M215 inverters.
3) 28- LG monoX 250W panels, 28- Enphase M215 inverters.

All of these were within $1,000 of each other.
Due length of time in business, price and equipment quoted, and the professionalism they demonstrated, I've decided to go with company #3. They came out and took the time to do actual solar readings on my roof top and determined the best direction and concentration for my panels. It surprised me as the other company's simply looked at Google maps and pre-determine the panel locations. #3 offered me better production placement on my roof that allows me to keep my pool solar. And even though they quoted in the middle, they were within $200 of the lowest price.

I'm looking forward to the project and the info that the Enphase Envoy will give me.


So, price per watt, sounds like a political answer to me.
If I use the DC rating and post rebate amount I'm looking $2.86 / Watt.
If I use the PTC rating and the post rebate amount I'm looking $3.28 / Watt.
This is installed, permits, labor, all equipment, plus moving one pool solar panel.

What do you think, Good / Bad / Ugly?

BB.

Re: n00b

Again, I am not in the business--So I am not the best one to say.

However, it looks like you scored a very good deal and did your research.

I don't know which power company you may be using... But look very closely at your billing plan. In Northern California (PG&E), I believe new installs are forced to go on an E6 Time of Use / Seasonal / Tiered billing plan.

The "plan" is very complex and not easy to describe to a family when they can and should not use power. There is summer/winter. There are up to three different rates (peak, partial Peak, off peak). There are tiered levels (the more power we use, the higher the rates). And there is weekday vs weekend/holiday 3 rate/2 rate differences. There is even another hidden feature, the utility meters bill on the "old" daylight savings time schedule--not the current schedule. And our rates (and pay back from GT solar) can vary from $0.10 to $0.50 per kWH.

It all boils down to when you use your power and if you have 1 year net metering (or something different).

If you can time shift (avoid using power from ~11am to 6pm summer weekdays, you avoid peak, and if you avoid power usage till 9pm you avoid partial peak).

What it all boils down too... It is confusing to "know" when to use/conserve power. And for folks with big power bills and (relatively) smaller solar GT power systems (many folks like to try something small first)--It is possible for a home's (or business) bill to actually be higher than the original "flat rate" residential billing.

See if your installer can give you a good idea of what your estimated power bill will be. And unless you know your time of day/tiered usages--It is pretty difficult to just "guess" at a number (not the installer's fault--just what a dedicated government/utility bureaucracy can do if they put their minds to something).

Commercial installs are even "worse" to figure out.

-Bill

Z714X4

Re: n00b

SCE, and it will be the yearly net metering plan. I don't know the specifics with net metering and tiers yet... I just know that the tiers brought tears to my eyes on a few bills and I'm shooting for a zero offset.

Thanks again for your input, much appreciated!

inetdog

Re: n00b

Z714X4 wrote: »

SCE, and it will be the yearly net metering plan. I don't know the specifics with net metering and tiers yet... I just know that the tiers brought tears to my eyes on a few bills and I'm shooting for a zero offset.

Thanks again for your input, much appreciated!

Just got my first bill from PG&E with smart-TOU-net-meter. And it brought "tiers" to my eyes too. :-(