Popular Post 007 RED Posted October 6, 2022 Popular Post Share Posted October 6, 2022 Today, 6/10/22, celebrates the 1st ‘birthday’ of my small scale grid tied solar system, so now is an opportune time to take stock and assess its performance during the past 365 days. Background The system comprises 4 x 415W half-cut mono panels connected in series to a 2.2kW Sofar grid tied inverter. The system was a DIY project, so there were no labour costs, just my time and effort. The total cost of the hardware worked out at a tad over 28,000 THB. We (my wife and I) consider ourselves to be ‘conservative’ electricity users with our bills, prior to installing the solar system, averaging around 1,000 THB per month. When I designed the system, I decided that the main objective of the system would be to reduce our electricity bills by approximately 75%. This would ensure that we didn’t get into a situation where the system generates negative readings when the meter reader calls. Under laboratory conditions, the 4 x 415W solar panels should be capable of producing 1.66kW, but of course were not living in a laboratory. In reality, the panels are more likely to produce around 1.25kW in good sunshine. Therefore, assuming 6 hours of good sunshine a day, the system should be able to produce (1.25 x 6) 7.5kWh a day, which is the figure that I considered to be the target for the system. What has the system achieved during its first year of operation? According to the system’s monitoring facility, it has generated 2,590kWh during the past 365 days, or an average of 7.1kWh per day. Attached below is a graph illustrating what the system has produced, and what we purchased, since 6/10/21 to date. I have also included what we purchased during the 9 months prior to the system becoming operational for comparison purposes. Looking at the graph below, it may be seen that we have slightly increased our consumption since the system became operational. I'll blame this on my better half who says that our electricity is free now ????. Since the system became operational it has produced approximately 70% of our household electrical needs, resulting in us only having to purchase about 30% from our local PEA. Although slightly lower than what I had hoped for, I still consider this to be perfectly acceptable, particularly given that the system was running in ‘NO EXPORT’ mode for nearly 3 weeks during May/June (See Note 1 below), and with very overcast conditions during late September/early October due to the monsoon season. Taking the cost of electricity as being 4.2 THB per unit (See note 2 below), the system has saved us (2,590 x 4.2) 10,878 THB during its first year of operation. Return on Investment If the system continues to produce the same output level over the next couple of years, it would be reasonable to assume that it will have paid for itself (28,000 / 10,875) in just over 2.5 years. Obviously if the price per unit of electricity increases, then the Return on Investment will be shorter ????. Problems Not wishing to speak to soon ????, but thankfully during its first year of operation there have been no major problems with the system. Shortly after turning the system on, I discovered that a MC4 cable connector (from the solar panels to the DC breaker box) was getting very warm. Upon investigation I realized that I had not fully crimped the cable inside the connector. Thankfully, this was identified/rectified before any real problems. Definitely my bad. The only maintenance the system has needed was to clean the panels on a couple of occasions to remove dust/dirt, although I’m not sure that this had any profound effect on the system’s performance. Will I up-grade the system? At this stage no. I’m very satisfied with the system’s performance and hopefully it will continue to provide a reasonable daily contribution to our electricity fund. If, and it’s a big if, the local PEA decide to replace our disc type meter with an electronic one, then I will have to seriously consider increasing the number of solar panels and possibly installing a second inverter. Note 1. I had to put the system into ‘NO EXPORT’ mode for almost 3 weeks during May/June because the new build house opposite was nearing completion and the electrical contractor had run the supply cables from the house to the pole outside our house, which also has our meter on it. As we had no idea how long it would be before the local PEA would come to install the meter for the new house we decided to go into a ‘safe’ mode, as we obviously didn’t want the meter installer to see the disc spinning backwards on our meter. Note 2. The figure that I have used (4.2 THB per unit) was the average that we paid per unit during the 9 months prior to installing the system. Note 3. On a light-hearted note. I recall a forum member some time ago suggesting that I was “penny pinching” by saving a few Baht a day. Well, I would ask, other than a ‘Ponzi scheme’, what investment is going to give me nearly 38% interest per annum.? If I was to put 28,000 THB into a basic bank savings account for the past year, I would be extremely lucky to get about 1,400 THB back in interest. Then to add insult to injury, whatever interest is paid would be automatically reduced by X% ‘with-holding tax’. So, at the end of the day a Return on Investment of 10,626 THB could well be considered a worthwhile payback. 3 5 1 1 Link to comment Share on other sites More sharing options...
Popular Post Encid Posted October 6, 2022 Popular Post Share Posted October 6, 2022 Congratulations @007 RED A savings of nearly 10.6K THB in your first year of operation is certainly a good return on your investment. Well done! 3 1 1 Link to comment Share on other sites More sharing options...
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