Hi guys, after (too) long deliberation and hesitation, I eventually started my PV installation.  I'm a pensioner so money is not abundant but I managed to get things started. I have a 8kW Deye hybrid, six 400 W panels from Proton Solar and one Pylontech UP 5000 4.8 kWh battery.  My electricity meter is old school analog and I was told that it would turn backwards if I produce surplus power. I need to witness that when the sun shines again. I live in Centurion.  I plan to expand, first with more panels and then with more battery.

I have a concern about the panels. I can't find any info about them on the www.  The maths tell me that the total rated power is 2400 W, but at midday in brief full sun I have seen only 1800 W. The panels are roof mounted on a 27 deg slope and facing 10 deg west of true north. Are the panels under-performing?  I don't want to complain to the supplier and make a box of myself if the panels are within acceptable limits.

Edited December 16, 20213 yr by hannesvn

36 minutes ago, hannesvn said:

total rated power is 2400 W, but at midday in brief full sun I have seen only 1800 W.

That's 75% of nominal; that's about right for a less than perfectly optimal setup. A system with a really optimal orientation and tilt might yield 80% of nominal in the best parts of the day.

Both of these will occasionally surge beyond those figures, but only briefly (tens of seconds) after the sun reappears from behind a cloud. 

My roof faces true north but has a suboptimal 7° tilt. I have briefly seen 5.88kW from my 6.37kWp array, or just over 92%. Your figures around 75% in an optimal installation make me wonder if you didn't get 6 x 300W insetad of 400W ...

28 minutes ago, stok said:

good day hannesvn, is the panels connected in one series string?

one UP5000 is way too light for a 8kw inverter, max continuous draw from a up5000 is 2.5kw just a heads up for future warranty purposes

Yes, connected in one series string....and yes, battery is now set up for 90% SOC, 2.5 kW draw should see me through a load shed.  Do you think it will be better to first expand the batteries rather than the panels?

15 minutes ago, Scubadude said:

6 x 300W insetad of 400W ...

 

Don’t need another battery right away unless  you have loads that exceed 2.5 kW when there is no grid, my loads are mostly during the day, so I maxed out pv panels. Next step when money is plentiful again, will buy another 5 kWh battery for a total of 10 kWh storage

Covered in some previous posts. You need to understand that the rated wattage is measured under ideal/standardized conditions, being something like a lowish temperature, clear atmospheric conditions, and light shining directly onto the panel at 90 degrees. If it's not dead-on you're basically spreading the sun's rays over a wider area and reducing output. Very rough thumbsucks here. Already the 10 degrees West will reduce the peak output by the cosine of 10 deg, about 1.6% and the inverter itself plus wiring will have a few more percent inefficiency, say 3-5% reduction. More than that, I think you need to factor in the angle of the incoming sunlight relative to the earth considering your latitude and the position of the sun during the season. As a rough thumbsuck, SA is around thirty degrees South, so this 27deg  is about a reasonable average roof angle to use throughout the whole year depending on location. Basically you're then  pointing your panels towards the equator, while the sun will move further away North in our Winter, and more South in our Summer. Right now the sun is sitting around 23 degrees South near the Tropic of Cancer at the height of our summer. So hannesvn's panels could see peak output reduced by a further 8-10% because it's still pointed at the equator roughly, compared to Scubadude whose panels are pointing nearly straight at the sun. Other than that, maybe double check if there's any dust or shading on the panels.

Thanks guys, I feel better about the panels now. I've plugged in my location , setup and angles to PVWatts calculator (https://pvwatts.nrel.gov/) and downloaded the hourly prediction, and it is very close yo what I get.

What is the house load? Maybe it's only 1800W, and that is all you'll see unless the batteries are charging, or you are pushing back to Eskom.

Either way, welcome to the solar family. 👍

@hannesvn

In terms of 1800W vs 2400W PV, there are many settings on the Deyer that affect the PV draw. The inverter will only draw as much as it needs from PV + Grid + Battery. When my battery full ~11;30am, PV drops to match Load for the rest of the day.

Edited December 16, 20213 yr by system32

yes, the wheel does spin backwards, sadly the units dont tick down.. 

with the exception of your panels, your equipment choices are excellent, the panels are likely rebranded so will do the job. the difference between getting 75% and 90% on them is soiling (measured on my system, weather excluded), so every now and then I get on the roof with the hose and foam mop, and give them a clean.

with the panels, you need to ensure availability in the future when its time to add more so your string is balanced

give this a try to see how many how additional panels/batteries you need - use the unit method, ignore the limited inverter options, the batteries are the same size as yours @ 100ah at 48v. also stick to your pylontech for future batteries.

https://shop.thesunpays.co.za/pages/solar-system-sizing-calculator

its not perfect, but gives an idea at least, quick and easy

Edited December 17, 20213 yr by Nitrious

A steep learning curve (for me) indeed.  It doesn't look as if the inverter is "choking" the power, but rather returning it to the grid.  This week was particularly bad in terms of sunshine, so it was difficult to get enough reliable data to come to a conclusion.  I will monitor my installation over the festive season and declare my disputes (if any) once businesses are open again.

I've seen a few things of interest, the DC voltage stays around 3.5 V during the night. It spiked to about 10 V during a thunderstorm (lightning?)  I also noticed that there is a 70 W difference between total grid and total consumption. I assume that is the system's internal use.

Thank you all for a very pleasant and informative two days on the forum.  Have a wonderfull Christmas and new year, and stay safe.

 

 

3 hours ago, Nitrious said:

yes, the wheel does spin backwards, sadly the units dont tick down.. 

Do I get ANY gain/ bill reduction out of this?

Grid tie, aka grid export is a expensive exercise, so no, the wheel spinning backwards in this case gives you no reward. 

Your panels are picking up around 60-70% of your load from your graph, you only use the balance from the grid, this is your current benefit. 

Another 4 panels should keep you from using grid power. However a proper analysis of your power needs hasn't been established yet. 

Perhaps discuss your objectives and steps taken so far, as a means to guage where you are with your goals

At least your system has good building blocks, with extra panels and maybe 1 or 2 extra batteries being the question

Edited December 17, 20213 yr by Nitrious

29 minutes ago, hannesvn said:

Do I get ANY gain/ bill reduction out of this?

Not all spinning wheel meters clock back the digits, as Nitriouse says, but check yours, maybe you are one of the lucky ones.

When I had my grid tie Infiniti with 260w panels back in the day, my meter went backwards, but no turning back on units used, would've been the best grid tie export ever, 1 to 1 ratio.

At least the op didn't get axpert'ed, so kudos to the supplier/installer on that front. All in all a decent start. 

Not to say they don't have their place, also I have one but that's another story, got it cheap

Edited December 17, 20213 yr by Nitrious

What are implications of my meter spinning backwards and my bill reducing by a substantial amount ... lets say I fit panels and get my electricity account to reduce by R1000 or R2000 per month ... which would result in drop to around R200 per month  ... wouldn't Eskom send someone out to check my meter ? ... lets say they only figure it out in  1 or 2 years time do they just right it off if they see I have a system installed ? 

1 hour ago, isetech said:

What are implications of my meter spinning backwards and my bill reducing by a substantial amount ... lets say I fit panels and get my electricity account to reduce by R1000 or R2000 per month ... which would result in drop to around R200 per month  ... wouldn't Eskom send someone out to check my meter ? ... lets say they only figure it out in  1 or 2 years time do they just right it off if they see I have a system installed ? 

If you are one of the lucky souls to have the "right" meter, don't push back all at once, or they might become suspicious. But on the other side, who's to say a child who enjoyed using heaters, etc, has not just left home for the great big world.😆

If they only figure it out 2 years later, they still don't know when you installed the system.

If your meter spins backwards, but doesn't turn back units, there's little point to export. Otherwise, ensure you never export more than you use in a month or at some stage your meter will be replaced. Think meter readings, and in essence your meter will be static or close enough. 

afaik your inverter has a do not export function while retaining grid tie (pls confirm) , failing that there's a device you can install between the house and the meter that stops grid export,while retaining grid tie. 

This in essence keeps you geyser and stove powered off solar without being connected through the inverter. 

Again, it's all about how the setup was done. 

Regarding next steps, think of it like an investment, eskom is looking for a 54% increase over the next 3 years. Your system once finalized to suitable panels and another battery plus a borehole should give around 27% return per year at current prices, depending on your w&l bill, and your system should be sized accordingly. 

My setup gives around 50% return per year, guaranteed. A solid investment by any standards, but one which I'll have to dilute eventually with inverter and battery upgrades.ev's are arriving eminently, and not paying for fuel again suits my general sense of keeping money in my bank account. 

As price increases kick in as all we know they will, roi % will just go up year by year. 

About the only thing left is some kind of tax write off for home users, something I'll look into actually. For businesses it's easy and already in place. 

Edit: tax consultantancy underway with one of the best I've ever known, 20 plus years in the industry, once I have feedback I'll update

Considerations are:

Remote workers

Office/on site employees 

Edited December 17, 20213 yr by Nitrious

On 2021/12/16 at 12:52 PM, hannesvn said:

Thanks guys, I feel better about the panels now. I've plugged in my location , setup and angles to PVWatts calculator (https://pvwatts.nrel.gov/) and downloaded the hourly prediction, and it is very close yo what I get.

I had similar concerns when my system was installed I used data and output from this site  https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#PVP  to provide a benchmark.