ROI After 2 Years

[007 RED]

My small scale Grid Tied Solar system has been running for 2 years, as of today.  So, I thought it was time to take stock of what it has achieved.

 

For those unfamiliar with my system, it basically comprises 4 x 415W half cut monocrystalline solar panels connected in series to a Sofar 2200TL-G3 grid tied inverter.  The system is mounted on our carport roof which faces South and is inclined at about 15^o, thus ‘catching’ as much sunlight as possible throughout the year.

 

 

From historical usage data, my wife and I appeared to be using around 9 units a day.  Not a lot when compared to many other forum members. Although we have air conditioners in the living room and the bedroom, these only get used when the humidity gets above 75%, and then only for relatively short periods of time to dry thing out.  We prefer to use fans whenever necessary.

 

When I originally designed the system, I determined that it should produce about 75% of our daily electrical needs so as not to get us into a negative meter reading situation.

 

The project and was based upon @Crossy original topic

 

The installation was DIY, so the only costs involved were for the hardware, which amounted to 28,000THB give, or take a few THB.

 

Prior to activating the system, we were paying our local PEA 4.2THB per unit, this comprised:-

 

(the cost of units used + connection charge + any FT adjustment + VAT) ÷ number of units used that month. 

 

So, for the purposes of evaluating the ROI I have continued to use 4.2THB/unit as the base cost of the units generated by the system.  Obviously, the price per unit has risen over time, so in reality the payback time will in fact be much quicker.

 

According to the monitoring system, as of this morning, the system has been operational for 730 days, during which time it has generated a grand total of 5,910 units, which at 4.2THB/unit, means that the system has reduced our PEA bills by 24,822THB during the past 2 years.

 

I anticipate that at the current rate of production, in approximately 3 months’ time the system will have paid for itself, and from then on it should be ‘profit’ .

 

28,000THB ROI in approximately 2.25 years has turned out to have been a very worthwhile investment, in my opinion.

 

As an added bonus, the Sofar monitoring facility also advises me that my small scale system has saved 1.8 tons of coal from being used, 4.68 tons of CO2 being emitted and 322 trees having been planted.   Don't ask were they got those figures from as I absolutely no idea.

 

Problems? 

No not really.  That said, because we live in a semi-industrial area, the panels do tend to get quite dirty and need regular cleaning which is a bit of PITA at my age climbing onto the carport roof.

 

We know which day the meter reader comes each month, so the system is switched into NO Export Mode the day before he comes, so this has never been a problem.   That said, my main worry has always been the PEA turning up unannounced and seeing the meter spinning backwards.  This did happen once when one of our neighbours apparently did not pay their bill and the PEA contractor arrived to disconnect their supply.  There are 5 meters (including ours) on the same pole outside our house.  I heard their pickup stop outside and realised who they were.  Fortunately, our washing machine at the time was going ‘hell for leather’ in its spin cycle, so if they had looked at our meter it was more than likely spinning in the right direction.  As an added precaution I also turned on our air con in the living room just to be absolutely sure.

 

Once they had gone, I turned the system into No Export Mode, knowing that they would be back in a few days to reconnect the supply once the neighbour had paid their bill.

 

Would I do anything different?

Basically, no.  I appreciate that the time may well come when our local PEA will come and replace their lovely spinning disc meter with a shiny new electronic one.  Obviously this will prevent the system feeding any surplus power back to the grid.  When that happens, I will have to consider our options.  Do I add a couple of extra panels and stick system permanently into No Export Mode, or do I upgrade to an expensive larger hybrid system with an ESS.  Only time will tell.

[Crossy]

Nice result ???? 

 

The options for "do it differently" have improved over the last few years.

 

There are a fair number of on/off grid hybrids now that will happily run as grid-tie with no ESS and export excess energy. When the no-reverse meter comes along add an ESS and re-configure the inverter to not export ???? 

 

EDIT For interest our 10.6kWP hybrid system with 12kWh ESS will pay for itself after about 5.25 years, 1.7 years to go ???? 

If we get there without getting an electronic meter I'll be happy, if we do get an electronic meter I'll have to add more storage which would push payback out to around 7.5 years total ???? 

[KhunLA]

Our 'installed/expensive' system, total off grid, but still conx to, should have a ROI in about 9 yrs, just energizing the house, if using 800 units a month on average, at today's rate.

 

Add the EVs to the ROI, and cuts that ROI time almost in half, if we continue to drive 20k kms a year.  Reality, probably 5-7 yrs ROI, as we'll probably drive less in coming years.  About 40% of the price of our system, are the ESSs (฿185k of ฿445k).

 

That 40% premium, only supplies 6-8kWh (~25%), overnight, of the 26kWh we use daily, on average.  Not exactly paying for itself, but, if prone to power outages (we're not) then damn convenient to have.

 

New build house, so we've had a digital meter almost from day 1.  As have every new house, about 13, built in the last 2 years here/PKK.

Edited October 6, 2023 by KhunLA

[Pink7]

1 hour ago, KhunLA said:

Our 'installed/expensive' system, total off grid, but still conx to, should have a ROI in about 9 yrs, just energizing the house, if using 800 units a month on average, at today's rate.

 

Add the EVs to the ROI, and cuts that ROI time almost in half, if we continue to drive 20k kms a year.  Reality, probably 5-7 yrs ROI, as we'll probably drive less in coming years.  About 40% of the price of our system, are the ESSs (฿185k of ฿445k).

 

That 40% premium, only supplies 6-8kWh (~25%), overnight, of the 26kWh we use daily, on average.  Not exactly paying for itself, but, if prone to power outages (we're not) then damn convenient to have.

 

New build house, so we've had a digital meter almost from day 1.  As have every new house, about 13, built in the last 2 years here/PKK.

The EV will do the magic for your ROI and must be counted !!! Im "semi offgrid" I dont have any grid supply to my inverters but i do have a ATS with grid power so im very exited to see hoe much i can live without it kicking in with any grid power. I guess 2-3 rainy days...

 

Pink

[007 RED]

6 hours ago, Crossy said:

Nice result ???? 

 

The options for "do it differently" have improved over the last few years.

 

There are a fair number of on/off grid hybrids now that will happily run as grid-tie with no ESS and export excess energy. When the no-reverse meter comes along add an ESS and re-configure the inverter to not export ???? 

 

EDIT For interest our 10.6kWP hybrid system with 12kWh ESS will pay for itself after about 5.25 years, 1.7 years to go ???? 

If we get there without getting an electronic meter I'll be happy, if we do get an electronic meter I'll have to add more storage which would push payback out to around 7.5 years total ???? 

I think that is certainly something that I may consider.  As you are aware, I'm currently using 4 x 415W solar panels on carport roof.  If required there is ample space to add a further 8 panels.  But then were getting into the realms of parallel connections etc, which is going to be a new learning curve for me.  That said, I love a challenge.

 

Many thanks for your suggestion.

[Muhendis]

3 hours ago, 007 RED said:

But then were getting into the realms of parallel connections etc, which is going to be a new learning curve for me.

Easy Peasy.

Check out combiner boxes.

These are boxes with fused input terminals for strings of panels which need to be paralleled. The outputs from the terminals are diode isolated from each other into a common connection. There will be a DC circuit breaker and a surge suppressor at the common output which then goes out of the box to your charge controller or inverter solar input.

Just make sure the Voc and charge controller/inverter input power (less derating factor) is not exceeded.

 

Edited October 6, 2023 by Muhendis

[007 RED]

UPDATE - ROI After 2.25 Years

 

Well, as predicted in my original post (above), my small scale grid tied system has really earnt its money over the past 2.25 years.  The system was a DIY install with the hardware costing 28,000THB (give or take a few THB).

 

According to the systems monitoring facility (as of this morning), the system has produced a grand total of 6,670 units, which at 4.2THB/unit (the total cost per unit on the day the system was activated), has resulted in a saving of 28,020THB on our electricity bills, as per screen shot below.

 

I appreciate that this is relatively small compared to the ‘big boys’, but it has proved a really worthwhile investment.  Each unit the system produces from now on is ‘profit’   .

 

In my original post I mentioned that the day may well come when the local PEA come and replace our lovely spinning disc meter with a shinny new electronic one.  Ironically, since I posted that remark, my better half received 2 phone calls from people purporting to be from the PEA and advising her that they (PEA) were coming the following day to install a digital meter.  On both occasions nobody from the PEA turned up and we still have our spinning disc meter.  It turned out that these were scam calls trying to get my wife to disclose her bank details on the pretext that they (PEA) would transfer a refund for the original meter into her account.  Thankfully she never disclosed any details to the callers.

 

As a result of those 2 calls, and the need to turn the system into NO EXPORT mode for a week (or so) after each call as a ‘safety’ precaution, I decided that I would upgrade my system by installing an additional 2 x 415W panels.  This upgrade would hopefully mean that even with the NO EXPORT mode activated, the system should be able to still meet approximately 75% of our day time needs without feeding back to the grid if required.

 

Luckily, I managed to get the additional panels from my original supplier (wow, still trading after 2 plus years).  Same make, with free delivery, and only a small increase in the costs of the panels.

 

The biggest task was getting the panels up onto the carport roof.  Unfortunately, this time there was no large crane available to lift them up there (for a moderate backhander).  It was shear man power, and a good deal of determination, but they are in place and they'll be connected tomorrow before sun rise, with everything being turned off to start with.

 

 

So looking forward to seeing a potential 50% increase in output tomorrow, with no 'magic smoke', fingers crossed.  All good fun.

Edited January 21 by 007 RED
Photo added

[007 RED]

Upgrade Update

 

Up at the crack of dawn yesterday morning to turn off the inverter and the system’s  AC and DC breakers before starting work to connect the two new panels to the existing panels on the carport roof.

 

I managed to complete the connection and securing the panels onto their mounts before the sun became to strong to continue working on the carport roof.

Back on terra firma, I did a quick check to ensure that the input polarity to the DC breaker was correct before switching everything back on.  Thankfully the needle on the AVO meter swung in the correct direction and showed a reading of 240V (DC), which with the 6 panels, and moderate sunlight, was about what I was expecting.

 

With fingers crossed, I turned on both of the system breakers and then switched the inverter on.  The inverter went into its start up check sequence and a few moments later the system showed “Normal operation”.  Fortunately no ‘flash bang’ or ‘magic smoke’ thank goodness.

 

A quick look at meter on the pole outside the house showed that it was merrily spinning backwards at a ‘rapid rate of knots’.  Upon checking the system’s monitoring facility (on my PC), the system showed a marked increase in power produced (e.g. about 40% plus) when compared against the same time the day before.

 

After a full day of operation the system monitoring facility shows about 45% increase in production, as can be seen from the graphs blow.  Given that there were a few intermittent clouds shading the sun during the day, the increase power production was as I was expecting.

 

 

So now having spent an additional 8,000 THB on the 2 extra panel, I hope that they quickly repay my moderate investment.

 

The only problem that I envisage is that with the added potential production there is a risk that my small scale system may well start pushing the spinning meter into negative territory, so this is something that I will need to monitor in the coming weeks as I certainly don't want the  when the meter reader comes next month.

 

All good fun.

[Dan O]

Great post. As you may remember I copied your layout with a couple minor charges about 1 year ago with similar results. I started with 4 - 450 watt 48 volt panels (Tier1)  from Homepro because they would deliver which is a major stumbling block if your out in remote areas. I just started to add 2 more panels myself and have the mounting hardware, frames, panels, etc and I'll be up on the roof later today and tomorrow pending the weather. Only hiccup I had was a bad data logger that worked intermittently. I was sent 2 replacements from Sofar for free. 1 replacement was the plug in RS232 style which was correct and the other is a screw on version that doesn't fit my model inverter. (if anyone needs that one shoot me a message).