New System Installed But Somewhat Disappointed?

[bcroe]

Several things on this thread, perhaps not concise:

1.) As long as the sun is above the horizon, any (panel) addition to a system, added in any orientation, will increase the instantaneous system output, full sun, or complete cloud cover, at any and all times of the day when the sun is up. For example, east facing panels added to a south facing array will add to solar noon output, just not as much as the south facing panels.

2.) Safety first: Any system changes must trigger a system review for impacts on the entire system and all components. For starters, to state adding non south panels will not require a larger inverter because it will not increase peak output is not correct. Peak output will increase. Maybe not much, maybe a lot. Probably somewhere in between, but it will go up.

3.) Bruce: Most commonly, "Nameplate Rating" refers to the S.T.C. rating of the panels used. Sometimes it is considered the S.T.C. rating of each panel times the # of panels to give total system size. Referring to "Nameplate Rating " by inverter size is uncommon to my experience, except perhaps in the subcontext of talking about inverters. Most of the time, a residential solar electric generating system is sized with some idea of the load to be met and the resource available to meet that load - the irradiance. The panels, their characteristics and number are then chosen to meet that duty. The inverter(s) that works best for the duty and the panels is decided after that, not before. The panels have priority in most design endeavors, not the other way around.

4.) On grid and off grid systems are different animals with different outputs, requirements and quirks. Since the OP has a grid system, I'd suspect most comments would be directed to grid systems.

5.) One goal of any solar design is usually most bang for the buck. This particular goal is most often best met when most of an array faces generally south to the greatest extent possible.

Other design constraints, requirements and priorities may likely require off south, split or unequal array sizes and orientations. Making the best choices between all/nothing is one way to think of the design process.

However, to think that east-west arrays or splitting arrays to off south orientation will be more cost effective simply and solely because it will make the daily production peak(s) a bit lower and also increase output some at other times of the day (thus, flattening the curve and putting "more area under the curve") is, in almost all cases, incorrect. Such orientations may be required by the design constraints, but the bottom line is, in most situations, it will cost more for less output, and thus not the first choice. Put another way, given any array or panel, south facing will, in almost all cases, produce more output per area than non south orientations.

6.) As stated elsewhere in this thread, S.T.C. ("Nameplate") output will be seen infrequently, if ever.

7.) The vendor's primary reason for existence is to make money by putting a solar product on your property. Many vendors are knowledgeable. Many are not. Some are unethical. A few are crooks. I'd guess the lousy ones are more of a PITA and more costly to the good vendors than they are to customers.

Regardless of their ethics or knowledgeability, increasing the customer's knowledge base is not part of their job description. For anyone to rely on someone with skin in the game for accurate, unbiased, always truthful information is foolish.

Caveat Emptor.

Part of the customer's responsibility in all this is to be as knowledgeable as possible about the product being considered and be aware of the consequences, financial and otherwise, of the choices made consistent with long and short term goals.

IMO, most folks' version of being knowledgeable is usually limited to being angry with the POCO for a bloated electric bill (mostly of the users' own doing), and throwing money at the problem by using the (usually) most expensive and thus least cost effective way to reduce an electric bill.

8.) OP has taken some hits here that IMO, could have been softer and gotten the same message across. But, the question (probably rhetorical) stays with me, if the OP had known, by heads' up objective, hard headed information gathering, some of what people knowledgeable with respect to solar energy know, would the same choices have been made ?

I wouldn't contest the above, I tried to always say "your situation may vary" in my suggestions.
HOWEVER....

"1. any (panel) addition to a system, added in any orientation, will increase the instantaneous
system output, full sun, or complete cloud cover"

Yes it will, and a simulation should be used to see the exact results. Just a matter of
adding up each panel group on an hour by hour basis.

"2.) Safety first: Any system changes must trigger a system review for impacts on the entire system"

Certainly.

"3.) Bruce: Most commonly, "Nameplate Rating" refers to the S.T.C. rating of the panels used. "

That answers my question. That rating system pretty much tracks the "all south" design
methods. It would be of minimal relevance to a multi oriented system.

"5.) One goal of any solar design is usually most bang for the buck."

"USUALLY", but not always. A lot of people rank money very highly; I am not one of them.

"However, to think that east-west arrays or splitting arrays to off south orientation will
be more cost effective simply and solely because it will make the daily production peak(s)
a bit lower and also increase output some at other times of the day (thus, flattening the
curve and putting "more area under the curve") is, in almost all cases, incorrect."

Here "ALMOST" is the key term. DO analyze your application, and DON'T FORGET
THE CLOUDS. My particular E-W payoff was MUCH more cost effective than the
south only portion.

Its pretty obvious that designs have mostly been driven by the idea of getting the most
from the precious PV panels, generally in a mostly sunny location. That is not what is
going on here, in the frequently overcast north central, and now that the cost of panels
has become a SMALL FRACTION of the total system.

Nor does this "science project" depend on a guaranteed return on investment;
somewhere near breaking even will do for this round. However, it is doing well.

My inverters were sized big enough to do the job (heat my house). I can think of 4
reasons why mine can't be any bigger. All that is needed, is to keep them loaded.
It became fast apparent that clouds were a make or break consideration. I haven't
seen ANY design methods to deal with clouds, just to write off those (frequent) days.

I decided that a lot more panels were needed to bring up power in marginal weather.
But MORE south facing panels would be of little benefit in good sun, just cause more
clipping. INSTEAD those panels would be oriented to produce when the south facing
panels were at minimum. This round may not be optimum; some south facing panels
might get moved someday. But a clamp on ammeter used in all situations has shown
it was a great first guess. In truth, there are enough panels to keep the inverters at
clipping all day long in good sun. But that is just another benefit of keeping output
high on so many overcast days.

Bruce Roe

[bcroe]

That was concise!

Yes, I got the original post on "reply to thread", before it got edited down to XXX. No
need to reply to that. Bruce Roe

[J.P.M.]

"3.) Bruce: Most commonly, "Nameplate Rating" refers to the S.T.C. rating of the panels used. "

That answers my question. That rating system pretty much tracks the "all south" design
methods. It would be of minimal relevance to a multi oriented system.

The S.T.C. rating method tracks nothing.

It's purpose, like other rating methods, is to measure panel output parameters under controlled input conditions. Different methods usually have slightly different test conditions, none of those conditions having anything to do with orientation except that the irradiance be normal to the panel being tested.

Test methods have no real relevance to "all south" or any other orientation. That's not their purpose or intent.