Best Posts in Thread: Sharing our experiences with Solar

I had been contemplating a solar panels installation for our house for considerable time, doing my research and trying to get a grasp of what would be possible.
At first I thought that maybe our roof (because of its shape, too many triangles and a rather steep angle) was not suited for solar panels at all but as I collected more information those suitability thoughts got adjusted a fair bit.
Yes, a roof with a 35 degree angle/incline will negatively affect the expected production from your panels, just like installing some panels on a roof facing north, or with some partial shade, but panels have gotten so much better (higher efficiency and cheaper) that these aspects no longer need to be a deal breaker. Yes I'm losing around 11% in electricity production compared to an ideal installation (all panels facing south, at an optimal 9% incline) but because we're so close to the equator, panels facing east, west or even north will still produce decent amounts of electricity.
A really good website with a freely usable good calculator that allows you to fiddle around with the details of your intended setup is found here . Just enter your location (barangay and town) and start fiddling around.
Another aspect that their calculator covers is the variability of electricity production through the year. Yes it's still averages per month, but to know that the worst months of the year (nov/dec/jan) will still produce around 2/3 of what you'd see during the best months (mar/apr/may) will help you to choose the size of the installation for your house.

So, how did I go about it. I started off with our monthly electricity bills, which showed an average use of around 600-700 Kwh per month. 600 Kwh per month translates into 20 Kwh per day. In our case I figured that about half of that use would be after dark until daybreak the next day.
Considering that when investing in a solar system I definitely wanted to make sure that we'd have no more brownouts and virtually no more Noreco bills, so we wanted to include battery storage to get us through the evenings/nights.
To achieve that goal we decided on putting 16 panels on our roof, 6 facing south, 6 facing north and 4 facing east, 605 watts each, so 9.68 Kw in total. Combined with an 8 kw inverter and 2 batteries, 51.2V, 300 Ah each so 30.72 kwh in total.
This setup will hopefully ensure that we can survive even 3 consecutive days with lousy weather without needing Noreco.
Our system was installed early this month, so our actual experience so far has covered only a very sunny period. On these mostly sunny days our batteries get fully charged by 10 or 11 am in the morning. In other words, during sunny weather we have plenty (potential) excess electricity production. I can (tested) run all 4 aircons in the house (5.5 hp) during sunny hours without pulling any power from the batteries.
Obviously things will be less rosy during rainy periods, but I am pretty confident that even during these periods our Noreco bill will remain minimal.

Financially, we invested around 600k Php in our system. My expectations are that the system will pay for itself in about 4.5 years (I calculated with a 5% yearly increase in the Noreco rate). So even with the expectation that the batteries will need replacement after 12 years and the inverter after 15 years, then we'll still end up with a really good return over the expected life of the installation that will exceed 20% p.a. on an IRR basis (internal rate of return).

 

For those interested in potentially installing a solar system themselves, here's a couple things you may want to consider.
The thinking you'd need to do yourself is mostly about what you want to achieve. If you don't mind still being exposed to occasional brownouts during the evening/night and wish to optimize your return on investment then you could leave out battery storage. You'll still have a monthly bill from Noreco then for the power used after dark, but if you don't run aircon all night long then that bill would not be all that high. Obviously, with net-metering in place that bill would be further reduced.

The answers to the questions about what you want to achieve will determine how much you're going to spend.
For most households a 5 kw installation without battery storage would suffice to mostly cover daytime electricity use. The 5 kw would mean putting 8 panels on your roof of 600W each. The maximum production of such a system in the Dumaguete area would be around 7,000 kwh per year assuming you can install the panels facing south and on a roof that's close to 10 degrees incline, around 750 kwh in the best months and around 550 kwh in the worst months of the year. In a less ideal situation you could simply add one or 2 additional panels to make up for the partial shade / facing east / steep incline (try fiddling around with the calculator at the link in my first post in this thread).
The return on investment for such a system would be even higher than mine (because batteries are relatively expensive).

My setup achieves a (almost) zero bill from Noreco and peace of mind about brownouts, but at the expense of a bigger investment (because of the batteries) and a somewhat lower return on investment.
When it comes to battery size, we chose to install more storage capacity than would be needed to bridge a single night. In part that choice was made to ensure that the batteries will almost never fully discharge (better for expected lifespan), and in part to have a bit more certainty that brownouts won't affect us even on a bad weather day.

 

When my solar system was installed last August electricity was about 10 pesos per KWh. The expected payback was about 5.5 years or about 19% ROI. With the current rate of about 13 pesos per KWh the ROI is about 24%. I can't think of an investment that pays anywhere near 24%.

My monthly Noreco bill was 6000 pesos (600 KWh) per month. Batteries are the most expensive part of the system. When I sized my batteries I made a couple of assumptions so the system would have excess capacity. It's not good to discharge the batteries to a low level. I decided to assume all consumption would be at night. That would leave me a fair margin in the batteries. Every day when the sun comes up and starts recharging the batteries they only dropped to about 40% which is close enough to what I expected.

I selected 5 KW of solar panels. My solar guy suggested 10 KW so I would have enough power on days with not so clear skies. I went with his suggestion and I'm glad I took his advice. The batteries are fully charged by 11 am on a sunny day and 3-4 pm on a not so sunny day. The angles and orientation of my roof did not help.
Solar panels are not that expensive, slightly less than 10 pesos per watt. More is better in my opinion. On the really sunny days it's pretty hot outside so I just relax inside in the Aircon for free.

I had a problem last week. One of my 2 strings of panels stopped working. The batteries took most of the day to charge and I didn't have to buy any electricity so not a big deal. When I had the solar cells installed I had the installer run a small diameter wire from each cell to a terminal block so I could trouble shoot a problem cell without have to crawl on the roof lifting solar panels.
When my guy came with his crew they went directly to the problem panel. Great!!! So 45 minutes later they are crawling all over the roof lifting panels. WTF??
To make a long story short the problem was a blown fuse. The blown fuse was a 15 amp fuse which should have been a 20 amp fuse. He had his guys check every fuse on the roof. Being conscientious really impressed me. Most people would have changed the fuse in 5 minutes and walked away.

My solar experience has been fantastic. I'm happier than a pig in poop.

 

As for how the installation works, it requires basically no user interaction at all, the system determines automatically what to do.
If there is a battery included in the system that's not full then any solar power production beyond what the household is using will be used to charge that battery. Once the battery is full, solar production will be either sent to the grid (in case of net-metering) or be limited to the actual household use of electricity. Once the solar production falls below the actual need for electricity in the household near the end of the day, the system will draw power from the battery as needed, or if there's no battery (or battery is empty/ at minimum discharge limit) then power will be drawn from the grid.
Depending on the brand and type of your converter (ours is a hybrid one from Deye) there may be an option to connect your inverter to the internet over Wi-Fi. Deye offers an app that allows you to monitor the performance of your system over time. Data is uploaded to the Deye cloud-server automatically and stored there. The AI-assisted app also allows you to set preferences for how the system should operate.

 

Some pictures to go with the thread:





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