Crossy

So, I've been asked on a number of occasions to clarify the various types of solar inverters and what they can do. Here's my Idiot's Guide. Off Grid So the classical solar installation would be a simple Off-Grid system. The panels charge the batteries and the batteries run the house. The grid is not involved anywhere although some users might install a generator type transfer switch so they can switch to grid or a generator if the batteries are dead. This system has the issue that the maximum load can never be greater then the inverter maximum output. On Grid or Grid-tie By far the most common system here in Thailand, it also happens to be the cheapest as there are no batteries involved. The inverter supplies power to the network whilst the sun shines, it is synchronised to the grid and so offsets the consumption from the grid. A plus of doing this is if you need more power than the solar is supplying it simply draws that extra energy from the grid in a totally seamless manner. On the negative side is that, because there are no batteries, if the mains goes off so does your local power even if the sun is beaming down. If you generate more power than your local loads are using then the excess is exported to the grid. The old disc-type meters happily run backwards during export saving up the energy for you to use later. This "net-metering" is technically illegal and if the meter reader sees the meter going backwards you will likely get a "no reverse" meter installed. If you already have an electronic meter these don't go backwards, indeed they might actually bill you for any power you export! In order to mitigate any export issues many on-grid inverters have a zero-export function so the inverter exactly matches what the load is using. Of course any extra power available from your panels is simply wasted. Off-Grid Hybrid In order to offset the disadvantages of an off-grid system the off-grid hybrid adds a mains powered battery charger into the mix. This allows the mains to top up the batteries or "help" the solar if the sun is feeling tired. Most have a "bypass" which allows the load to operate directly off the grid if necessary. These hybrids usually have several modes available depending upon how you want it to behave. The usual setting would be "Solar First" whereby the load draws power from the solar most of the time, if there's not enough solar then the extra comes from the batteries and if there's still not enough (batteries discharged) then the remainder comes from the mains. Of course, so long as you have solar and/or juice in the batteries you never actually end up in the dark even if the grid is off. Like the simple off-grid system this unit still has the issue that the maximum load can never be greater then the inverter maximum output. On-Grid Hybrid The on-grid hybrid is really the ultimate system combining all the advantages of off-grid (never in the dark) with the advantages of on-grid (no limit on power available if the grid is on). Again there are many modes to choose from the usual one would be "Self Usage". The inverter attempts to keep your grid current at zero where it can. If there's excess solar it charges the batteries, if there's not enough solar energy is pulled from the batteries to keep your grid consumption at zero. Most also have an "Essential Power" output which gives UPS like functionality when the mains is off to keep your important stuff (lights, TV, PC etc.) running when the grid is down. Like the on-grid systems these inverters can export to the grid if the batteries are full and you are making more than you are using. The same caveats regarding net-metering apply of course.

IMPORTANT UPDATE 25/04/22 - All of the guides etc. are now at https://www.localfoodheroes.com/ the links are later in the thread but since we are seeing interest again I've edited the OP. As a Brit I like my bacon sliced a bit thicker than is commonly available here at a sensible price. I'd also rather have "back bacon" not the "streaky" which seems the norm. So I had a go at curing my own. Instructions here http://www.localfoodheroes.co.uk/?e=541 do follow the quantities accurately. Prague Powder #1 from Lazada - https://www.lazada.co.th/products/i168877082-s209361163.html Ziploc bags, Lazada again (I got the biggest I could find) - https://www.lazada.co.th/products/i2330372790-s7881063502.html I left out the optional sodium ascorbate 'coz I couldn't find it. Pig loin from makro, looked for a piece with a bit of fat. I did just a 1kg piece just in case it went wrong, this was a mistake, should have done more After 6 of the longest days in my life we have a result. Looks, smells and tastes just like the real thing. Deemed totally acceptable by Madam, we've nearly scoffed the lot already. Hand slicing, even with Madam's razor sharp cleaver wasn't perfect. Slicing machine on order.

Some of you may remember us building this back in 2015. Thread here https://forum.thaivisa.com/topic/481794-housebuilding-thread/?do=findComment&comment=9603407 Well the time has finally arrived for me to get my finger out and actually put some solar on the car port. We spoke to our local PEA office who were quite enthusiastic and helpful until we said we didn't want to join the government scheme (IIRC it's called My Solar Roof), the contract was too long and restrictive and the feed-in rate silly. So, we are NOT permitted to spin the meter backwards (net-metering) - At least not officially "don't let the meter reader see it going backwards" said the supervisor (he's not over enamoured with the government scheme either). That along with the costs associated with doing the job "officially", approved inverters, approved installers (no DIY) decided me to do this on the QT. Luckily for us (but not my wallet) we have a standing load of about 1100 Watts (mostly Madam's koi and the freezers), our base consumption hasn't gone below 1000 W for the last year or so (yes, I'm sad, we keep a log - ok the supply monitor does). So 1000W or so of solar would cover the base without the meter going backwards and still produce a visible saving on the power bill. A quick and dirty estimate:- 1000W x 5 hours per day = 5 units per day generated. Times 30 days per month = 150 units per month. @ 4 Baht per unit thats 600 Baht per month = 1 case of beer!! Our bill is usually 5500-6000 Baht so 10% reduction, enough to keep Madam's green desires happy. So I went shopping:- 4 x 300W solar panels from Global House - On offer at 3,890 Baht a pop. 2 x 600W WVC micro-inverters from AliExpress - 6,500 Baht for the two including duties and VAT. The cost of the "proper" mounting hardware scared me so a visit to our local steel supplier got us 11/2" square x 2mm wall thickness at 300 Baht a 6m length. I got 6 pieces, we don't need it all for 4 panels but I'm going to put all the mounting stuff up whilst I'm in roof-climbing mode. So 1800 Baht. We also need some stand-off parts to keep everything off the actual roof, I had some 3" x 11/2" x 2mm "in stock" so I made 36 x 100mm long stand off pieces. This steel would probably cost another 400 Baht or so. Washers, self drilling screws, angle fixings, primer and paint are all from stock, but I doubt they would cost more than a grand or so. So, we've spent about 25 grand to save 600 Baht a month. Payback period 41 months, about 3.5 years. I can live with that. I've not decided how to configure the rest of the roof space (there is room for 18 panels) yet, but if back-feeding remains off the option list I expect something with batteries is going to be on the cards (look up hybrid inverters). This would also provide a whole-house UPS facility and render our (noisy) genset redundant. Photos as we progress so hopefully all will become clear. Comments always welcome of course (or I wouldn't be posting).

Statement of the Obvious: Electricity is dangerous, any and all electrical equipment in your home is quite capable of ending your life. Like fire, electricity is a good friend and a bad master. ALWAYS turn off the power before doing anything on your installation, even just taking the lid off to "have a look''. Disclaimer: Although TV Moderators will, through enforcement of the Local Forum Rules below and periodic input, attempt to ensure that factual information presented in this forum is accurate and that advice provided does not contravene generally accepted electrical standards, it is not possible for Moderators to screen every post, and inaccuracies/improper advice will at times appear. In addition, there are inherent limitations to the provision of electrical related advice in an international internet forum where posters are from different countries with varying electrical regulations. Posters often fail to include, or misreport, pertinent information, and physical examination of an installation is, obviously, not possible. The knowledge and expertise of those who respond to posts varies considerably and their qualifications and experience, even if stated by them, cannot be verified. TV will not be liable for any adverse consequences that may result from advice or information provided in this forum. Members who offer electrical related advice or recommendations do so on their own accord and are solely responsible for the content; this applies equally to members who are also TV Moderators. Readers are responsible for deciding which, if any, advice or information found in this forum to accept. Local Forum Rules: The moderator's referee's decision is final. We all like a laugh and the occupants of this forum are no exception, but please let's keep it within reason. Any posts which offer advice which is considered dangerous will be removed without notice, if you see one please use the 'Report' button. This section is Work in Progress, please check back regularly for updates