New Guy..System Upgrade (actually system replacement) question

[SolTex]

PVWatts is fun to play with, and in our case it was very accurate. We used the calculator to check against the system "sizing" recommendations of our installer. Our goal was to cover 25,000 kWh of consumption per year. The calculator said our system would produce about 26,000 and after our first year of operation we are running at 101% of the prediction. So pretty close!

Note that most of the parameters in the calculator can be tweaked to your liking. For instance, you can run it with a DC/AC ratio of 1.2 (which is default). Then run it again with a DC/AC ratio of 1.0 and see how the total annual production number changes. Very interesting!

[ard]

Hmmm. Inputting my system in PVWatts, then downloading the excel spreadsheet for hourly production... looking at how many days I would be production over 11,400W

Is that the idea?

Just took a quick spin. Getting late, will drill down tomorrow.

thx

[ard]

1. 95682
2. Arrays are placed due south. Dont want to alter this, holes and concrete and all...
3. No. And google isn't helping....
4. PVWatts looks to be the NREL tool for estimating solar production? Have not used it, just found it- and will start plugging away..
5. PGE
6. ?
7. My current sunpower 7.7kw system results in an annual true up of $3000 a year. Id like it to be much less.... Large home, two ACs, shop, pool, landscaping- on a well, so all water is pumped from 400ft down. And will probably by an EV in the next year. Presently it seems that my system is meeting 50% of my (current) power needs

[J.P.M.]

Ard:

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

Q's:
1.) What's your zip?
2.) What panel orientation(s) are you considering for the new array(s) ?
3.) Are you familiar with SAM?
4.) Are you familiar with PVWatts ?
5.) Who is your utility provider ?
7.) What are your design goals for the new, proposed PV system ?

J.P.M.

[SolTex]

Hello from a fairly new-to-solar forum member. Our system has been up and running for just over 1 year, and we are very pleased with the performance. I only feel qualified to respond one of your questions:

"I assume with a 14.4kw system I want an inverter that will handle 14.4kw. Is this accurate? (I have someone telling me the solaredge 11.4 will be fine?...) Ive read up on oversizing PV arrays.... still not sure why a -say- 14.4Kw inverter wouldn't give me more, even only on some days at some times. Running the SolarEdge Designer tool, my system comes up as "126%" oversized."

If you have read up on oversizing PV arrays, then you have probably heard the justification for doing so. Whether you believe the justification is what matters. I fall into the camp that believes...but I'm always open to reasonable arguments pro and con. I've learned that "one size does NOT fit all" when it comes to solar design. What I can say is that our system works great, and it has a oversized PV array.

We have 40 LG380 panels, so our nominal STC (DC) system size is 15.2kW. The total peak (AC) output rating of our 40 IQ7+ inverters is (40 x 295W) 11.8kW. We see our system clip at the 11.8kW level for a few hours around noon every (sunny) day. In spite of this, our system exactly meets our design criteria to offset our annual consumption 100% so we are happy campers.

IF you wish to oversize your PV array (or undersize your inverter) then one widely accepted rule-of-thumb is to shoot for a DC/AC ratio of around 1.25 to achieve optimum annual performance. So for your proposed 14.4kW system a 11.4kW inverter would be (as someone told you) just fine. I can't tell you that this ILR (Inverter Loading Ratio) works for every situation, but it does work for us, and we have conditions very similar to what you describe (HOT in the summer, 30-40 days over 100F. Rarely freezes. Once a year snow).

[ard]

First post updated.... any inputs much appreciated.

[Ampster]

I guess our Admin felt the anti spam software was better then having to deal with spammers. Although it seems to catch just about anyone that the software feels is not right.

Yes it is a reasonable compromise.

[ard]

Thanks all.

I did compose the post in an outlook email editor, then pasted it. But scrubbed it by pasting into notepad, looking for anything hidden....

I'll get it fixed tonight, again appreciate to hear im not crazy. (interesting tip from bruce- the 'paste first' might indeed be the kind of action spammers might use....)

I did a few things:

Didnt paste the whole thing.... left the first couple of sentences as is, added content after that.... did the paste in pieces, not all at once.

The gods smiled!

[bcroe]

I find, check your posts carefully before hitting POST REPLY. Going back
to fix some trivial error may send it to moderation, but not if you wait a
couple hours.

I also had trouble writing something off line and then using copy and paste
here. But I just type a couple letters AND THEN paste, works. Delete those
extra letters.

Bruce Roe

[SunEagle]

I have had similar issues with making grammar changes with posts which contain links. They go to moderation.

I guess our Admin felt the anti spam software was better then having to deal with spammers. Although it seems to catch just about anyone that the software feels is not right.

[Ampster]

I would suggest you not modify any post for a while. The anti-spam software may take that as someone getting in and then adding a spam link.

I have had similar issues with making grammar changes with posts which contain links. They go to moderation.

[SunEagle]

Im confused as to why it truncated my post.

I tried to fix it- editing and searching for anything in the text that would cause it to truncate

I dont 'plan on causing issues'

Im really at quite a loss here. Please give me a suggestion as to how I post and not run afoul of rules or 'anti spam software'. I admin, design and moderate 4 other Vbulleting forums- happy to comply with whatever you need.

thx

I would suggest you not modify any post for a while. The anti-spam software may take that as someone getting in and then adding a spam link.

[ard]

It worked!

[SunEagle]

Im confused..why is the post truncated? Some moderation thing??? FWIW I run several VBulletin forums, yes spamming is a pita

and after editing the post 6 times and scrubbing it for ANY signs of odd content, it finally gave me a warning and said it was being moderated....

The anti spam software will note that if someone modifies an early or first post the post will go to moderation. If you plan on causing issues then you get banned and the posts deleted.

[ard]

Im confused..why is the post truncated? Some moderation thing??? FWIW I run several VBulletin forums, yes spamming is a pita

and after editing the post 6 times and scrubbing it for ANY signs of odd content, it finally gave me a warning and said it was being moderated....