Solar Airconditioners for landed homes

[leechaorui 2]

Hi all,  I just purchased a  6060 sqft landed semi detached house.  A&A was done in 2000.  Not sure if I will rebuild it as construction cost is at an all time high now due to a shortage of workers and the current Covid-19 situation.  As I may only rebuild the house when the situation is more stable, thinking of whether I should change the existing old air-conditioners into China made solar aircon or Mitsubishi aircon.  I have good experience with Mitsubishi aircon and inverter aircon doesn't really consume that much energy.  Anyone got experience with solar aircon?  As my area has sun all year round and the surrounding are quite empty, it is a good location to get a lot of sun.  Appreciate any advice including any contractors that I should or should not deal with.  Thank you.

[snoozee 97]

in order for solar aircon to work at night, you will need to have some sort of battery storage to store all the electricity generated during the day. are you prepared to take the risk of installing big power walls with lithium ion batteries? i'm sure you have read the news over the last few years where PMD charging caused fires in flats.

[leechaorui 2]

Yes, indeed that is a consideration.  Hence, want to check whether anyone here has installed solar aircon.  It has been installed in quite a number of commercial buildings and government agencies.  However, it may be quite trailblazing to install in a private house.  Also not not sure of the maintenance issues.  These products are all made in China and they retail for less than conventional Mitsubishi inverter aircon.  However, when they are marketed and installed in SG, the cost rise by a few fold and cost more than conventional aircon. 

[Topline 1]

In terms of costs savings, would a solar air con (which also requires solar panels to be mounted on roofs) be more cost efficient compared to a general solar panel that generates electricity for use for more than just the air con?

Cos the latter option doesn't require a separate compressor and indoor unit (just to use solar) which also takes up addtional space ... you can use normal applicances, i think.

Edited July 6, 2021 by Topline
Error

[snoozee 97]

my view on installing PV panels is that you are essentially paying for the electricity for the next 7 to 10 years up front. PV panels don't last forever and you will need to maintain them maybe after 5 years or so with parts needing replacing.

while it sounds sexy that you can get free electricity, the reality is that you need to pay for the equipment first.

let's just say the entire set up costs you $21k with ROI of 7 years. so your cost per year is $3k or $250 per month.

if your house electricity usage is not going to exceed $250 per month based on SP tariffs, then you are in fact paying more for electricity for the so called savings.

while there are grid tied systems where you can sell back excess electricity, you need to factor in the deduction of transmission cost for this. also in order to really pay for no additional cost, your day time generation and sale must be equal or more than your night time usage when electricity can't be generated by the PV panels.

so unless SP's tariffs shoot up to 40cts or 50cts per kwh, you are better off signing up for SP wholesale rates for now instead of investing in PV panels now. just provision for the wiring now and if the technology improves to much in future, you can do the installation then. 

[Topline 1]

Thanks Snoozee. May i ask what's your rationale for buying SP wholesale electricity compared to those fixed price ones offered by the retailers like Keppel?

[snoozee 97]

SP wholesale price

Pros
- no contract
- normally cheaper than other retailers

cons
- subject to supply demand so rate is not fixed

for example when electricity prices increased this year, those home owners who have signed contract with retailers at a lower rate will benefit since they are locked in at the lower rates for the contract period. but when SP tariff drops, these home owners who have signed contracts at a higher rate will still be bound at the contractual rate though this would normally still be lower than the standard SP tariff

The SP standard tariff for the last quarter is at 22.55cts per kwh. I'm was paying around 17.45cts per kwh on the wholesale rate. so basically a savings of about 5cts per kwh

[Kellhound 4]

There's a good movie documentary called "Planet of the Humans" by Michael Moore on Youtube that talks about the feasibility/viability (or lack thereof) of solar/wind energy. I believe you will think differently about solar panels and electric cars etc. after watching. Real eye opener.

Edited July 7, 2021 by Kellhound

[Topline 1]

On 7/6/2021 at 12:35 PM, snoozee said:

my view on installing PV panels is that you are essentially paying for the electricity for the next 7 to 10 years up front. PV panels don't last forever and you will need to maintain them maybe after 5 years or so with parts needing replacing.

while it sounds sexy that you can get free electricity, the reality is that you need to pay for the equipment first.

let's just say the entire set up costs you $21k with ROI of 7 years. so your cost per year is $3k or $250 per month.

if your house electricity usage is not going to exceed $250 per month based on SP tariffs, then you are in fact paying more for electricity for the so called savings.

while there are grid tied systems where you can sell back excess electricity, you need to factor in the deduction of transmission cost for this. also in order to really pay for no additional cost, your day time generation and sale must be equal or more than your night time usage when electricity can't be generated by the PV panels.

so unless SP's tariffs shoot up to 40cts or 50cts per kwh, you are better off signing up for SP wholesale rates for now instead of investing in PV panels now. just provision for the wiring now and if the technology improves to much in future, you can do the installation then. 

Hi Snoozee, these solar panels can last 20-30 years right? So even with 7 years ROI, from 8 years on you would be using the set up for free, no? I suspect when the SP tariffs shoot up to 40 cts kwh, the installation costs for the panels would also shoot up by then, such that ROI is still 6-7 years 🙂

[snoozee 97]

1 hour ago, Topline said:

Hi Snoozee, these solar panels can last 20-30 years right? So even with 7 years ROI, from 8 years on you would be using the set up for free, no? I suspect when the SP tariffs shoot up to 40 cts kwh, the installation costs for the panels would also shoot up by then, such that ROI is still 6-7 years 🙂

overtime the panels will lose its efficiency. at new, the panels may give you more than 90% efficiency and after ten years, the efficiency may drop to 80% or lower.

in a PV system, panels are just part of it. you still have the invertors and other electrical components within the system. assuming that the lifespan of the inverter lasts for 8 to 10 years, you will still be looking to change it at least another 2 times within the lifespan of the entire system which could be a few K each time.

I've seen proposals from PV install companies which calculate the ROI based on perpetual increase of SP tariffs. but the reality is that the tariffs doesn't increase all the time. for SP tariff to hit 40cts, you will need oil prices to go up by at least another 40 percent. back in july 2008, electrical tariffs was about 30.5cts when global crude oil was about USD139. Today crude oil is trading at about USD75. So unless something major happens and global crude oil goes up to USD150, it is unlikely we will see SP tariffs at 40cts anytime soon.