Many lessons learned on my path into solar!
Here are some of my most recent leanings on the way to hacking into the Firmware.
* Wind blew two of my 460W panels off of an elevated structure. They were both already shattered. One seems about the same, the other was *almost* punctured but still electrically connected. Threw them back up, 6 panels put out 300V and I need to get back for some short circuit current testing and MPPT load testing.
* Had my first bad(ish) interaction with Signature Solar. I bought right before the Holidays (Xmass Eve,... remember... I am a TEST ENGINEER) lol. Took them forever to ship my goods, so... they are having growing pains. My second 5000ES arrived with a battery buss bar nut rattling around in the main compartment. That was fun.
I bought the combo kit (with Auto Inverter) and this time it shipped with a different version. This one showed up with undersized and rattling loose mounting fasteners. One was rolling around, three were backed out, all were missing washers. Fine - but - two boxes of loose screws???
I dont mind Loose Screws*
* Signature Solar has not been answering the phone, ... and when they answered Emails it was very weird. They did not "reply" with quoted text, but replied out of context in a new thread and did not answer my question. Eh hem, bad news. Good Communication is paramount for business.
I have been shaking down outfits like this for a LONG TIME. Folks will learn what is important and what is not. For me... Loose Screws and sparse customer support is not a problem at all. BUT... when it comes time to start dealing with FAILURES... they will figure out RIGHT QUICK when methods starts ripping into them. I am a fierce Engineer with 20 years experience and I set a pretty low bar for "Works". So far what they have sent me "works" - so we are on good terms until things start breaking.
SO
Putting them on Warm Standby until the failures start occurring. I dont like slow shipping or poor communication, so for the next setup I will probably use a different source. I still need to buy 1 more 5000ES to make my 10KW setup (15KW inverters to support 10KW continuous draw).
* Got into that Solar City 5KW inverter for a while. I have it wired in on some 8AWG with 7pcs of 460W panels. Due to my angles I was only able to pull a couple KW, but... it works pretty damn turnkey. I was very unhappy with the MPPT algorithm they are running. It is complete trash at anything but full sunlight. I absolutely guarantee that at low light levels the box is under-performing. Clearly on purpose, ... so... perhaps for some reason that I do not yet understand (or maybe thats why they went out of business).
* Scratching my head hard on why the bypass diodes in the panels dont allow full current to flow when 1 of 7 modules is shaded. I cant for the life of me figure out why 7 modules pushing 9A would drop to 3A when one module shades out. What should happen, is the array voltage should drop by 50V and short circuit past the shaded module. Then, the remaining 6 should keep pushing 9A.
I need to do the MPPT math on that, and see if it is just my GroWatt that is doing it.
Example
50V * 6 modules = 300V
10A * 300V = 3KW
50V * 5 modules = 250V
10A * 250V = 2.5KW
These are round numbers only, for relative comparison. So it we completely drop a module out that is 500W off the stack. Now how does that play out when we start to MPPT it?
All the modules will open circuit 50V
All the modules MPPT to around 42V
All the modules will push 9 - 10.5A short circuit
4 of the modules will short circuit 8A as placed
2 of the modules will short circuit 6A as placed
So what should I see in this example? What is the Maximum Power?
42V * 6A * 6modules = ~1500W
42V * 8A * 4modules = ~1344W
OH - DOH
It is higher power to run all of the modules at the lowest modules current while keeping its Voltage UP, as opposed to shorting across that module - IN THIS CASE - but as the array gets longer, the current should outweigh the voltage loss as the ... er....
Power = Volts x Amps
If a Panel shorts out to conduct current, that is a loss of 50 in the above equation... to gain 2...
Yea - ok - what I am seeing actually makes sense
PAUSE
(I woke up at 3AM again, horrible nightmares)
ONWARD
* We broke ground on the power run to the 32 module array. This is the setup where we are taking 32 of the broken 460W panels and mounting them all together in some kind of Series Parallel. At this exact moment in time my plan is to pull 6pcs of 10AWG + ground thru the 2" pipes. I figure with this... I can configure anything that makes sense. I will have 3pcs of GroWatt down in the shack, so I will need to run 3 arrays. The GroWatt wont over-draw 10AWG, so... should be fine.
1/3 of the trench is cut. Still need to do the upper and lower trenches. I am going to break it up into 3 runs of about 100 feet. I am figuring something like... 10A continuous on the 10AWG so I do not anticipate a bunch of line loss. To accomplish this, I MUST run the three arrays in Series, ...
So back to Shading
* Array Math
Target voltage is 420V unloaded. 420V / 50V = 8.4 = 8 or 9 panels. Call it 8 to keep things symmetrical. 8 panels loaded down to 42V pushing 9A will come in around 378W * 8 = 3KW. Three arrays of 3KW should get me 9KW, which is close enough to optimal.
BUT
To even DREAM of landing that, I have to... have to... Have To... HAVE TO... aim the panels perfectly at the sun***
MUST AIM DIRECTLY AT SUN
So
I am calling my first install of 6 panels elevated a TOTAL FAILURE and I am moving over to Pole Mount. Poles allow both rotation and elevation adjustment - so - I can start by hand adjusting and collecting data, then I can get my Linear Actuators on there. The actuator system will come in around $100 (Two actuators, controller, sensor, brackets, cabling, housing.. all DIY) so we double that, figure $200 each for 5 systems and ... a lot of labor.
So
That will come together - but - what I am stuck on right now is the damn Pole Mount costs. FLIPPING EXPENSIVE - and... 8 panels are HUGE and the wind will catch them and they are HEAVY... 60lbs x 8 = 480lbs... add to that the mounting, so figure 20% at least, maybe far more... we are going to have to call it 600lbs.
I need to put a 600lb kite up on a pole (OMFG) and wiggle it around with cheapo linear actuators (sigh). 3 large poles, each holding 8 panels.
That is what I am currently trying to Riddle Solve
Note: This mount is discontinued. Please look at these alternative Tamarack top of pole mounts, the UNI-PGRM/4P1 or the TTP-4.
www.solar-electric.com
I am of course reverse engineering everything I can find.
Just harvesting ideas and things that WONT work - lol - like that Amazon system. Lol, bend that thing over double.
- Need large poles, 3 of them, must be round so I can rotate
- Need to build 1 proof of concept
ONWARD
Largest Risks so far
* WIND
My biggest mistake so far was underestimating the power of the wind.
-methods