Thread by @MarcDaoud3

Ok since a lot of people are asking, I will try to answer. Long thread ahead
PV systems are complicated ones, and there is a lot of internal specs/configs that you need to look for. Suppliers give a very basic offer without any details
#PoweringLebanon (sorry @Jessica_Obeid)
1/n

https://twitter.com/eliasboustani/status/1437490160028037125

If they want you to pay 5k+, they better be able to answer questions. The costumer has the right to get all the data sheets, calculation notes (for estimated PV production, cables sizing, protection devices..). I am seeing quotations of half a page, this is unacceptable 2/n

1- Start with the equipment datasheets, and check on the manufacturer website (some are cheap counterfeit). For the panels look for lifetime and guaranteed efficiency drop. For batteries look for DoD/nbr of cycles curve. For inverters you need to look for a lot of things 3/n

2- What is the mounting structure used ? Is it painted black steel/galvanised/aluminum or other ? Weight, origin, lifetime, maintenance requirements ? How they will be fixed to the roof ? What abt wind/snow load ? 4/n

3- Cables sizing, especially on DC side. This would be related to nbr of panels and strings, voltage level, cable run. Cables quality (specific PV cables are required from panels to MPPT), installation mode and connectors (For God's sake MC4 weather proof connectors) 5/n

4- Batteries technology, acceptable DoD and expected lifetime, efficiency and how they are affected by temperature (depending on installation location). Maintenance requirements, and risks of overcharge 6/n

5- Is the MPPT built into the inverter or independent ? What is the maximum capacity (and what happens if i surpass it), nbr of strings and voltage, and tracking technology 7/n

6- PV panels technology and the expected PV yield ALL YEAR ROUND. Ask for a simulation specifically for your case or better do it urself (several free websites/softwares) depending on installed capacity kWp, orientation, tilt, shading... 8/n

Installed panels capacity is expressed in kW peak. Trust me you will almost never reach this capacity, not even in ideal conditions. So using it for calculations is WRONG. My 3.35kWp system never reached more than 3.1kW and typically produces 17-18kWh on a sunny summer day 9/n

7- For the inverter you need to dig deep, really deep. Nbr of AC inputs and Outputs, waveform (true sine wave is best), acceptable frequency and voltage range, anti islanding technology, on-grid/off-grid or hybrid; switching time, maximum capacity with/without grid. Capacity 10/n

Should be expressed in kW and not only kVA (most have a 0.8 power factor while the load doesn't); AND HOW THE CAPACITY IS AFFECTED BY TEMPERATURE. Built-in MPPT or not, built-in charger or not (and the maximum charging current possible).Options such as limiting input current 11/n

Limiting charging current, scheduling charging times, battery management, feed-in modes (and EDL approval). Check if CE certified, ask abt efficiency (usually dropped in calculations). Load control/shed strategies, operation in parallel, expansion possibilities, reporting 12/n

and communication modes (screen, bluetooth, web...),
data sampling and recording...
8- Accessories, for God's sake good quality accessories: DC breakers (between panels and MPPT, and between batteries and Busbar) and bus bars, AC breakers and bypass switch, AC and DC surge 13/n

arrestors (good quality), EARTHING plz plz plz, combiner box, cables lugs for God's sake.
9- You need to understand/monitor your energy consumption. There is no one size fits all here. Do install a solar hot water system before the PV system and check your options for winter 14/n

(like heating water through the central heating system or other), avoid heating water with power from ur PV system at all costs. AC and refrigerators are big energy consumers, switch to inverter technology. Schedule laundry/ironing to sunny hours or when grid is available 15/n

Having a PV system covering all ur energy needs in Lebanon is almost a myth, even fully replacing the backup generator is not always doable. We do get storms lasting for 3-4 days without sun even at sea level. Replacing genset is doable most of the days IF you have like 12hr 16/n

Of EDL power; unless you really oversized your panels and batteries, and still no sun=no PV production. Best to keep the genset connected and trip the breaker on sunny days (so pay only the subscription fee), and then reconnect it during cloudy/stormy days 17/n

It goes without saying that u should switch to LED lighting if not done yet
10- Batteries need time to charge, there is a charging cycle to respect and maximum allowable charging capacity. Even with an unlimited source of power (say EDL), YOU NEED TIME, a couple of hours 18/n

aren't enough.
Suppliers will try to trick in ur load estimation, in the batteries lifetime/charging and DoD, they will discard the batteries and inverter efficiency (you will lose easily 10-15% of the energy stored), in the PV yield. They will undersize the cables, miss the 19/n

accessories (or use cheap ones) and the earthing, never tell you abt programming and control options (which are essential in Lebanon). PV systems are not tailored for the Lebanese case, so some tweeking could be needed. And when the system fails they will blame it on "bad" 20/n

EDL or generator electricity, on overconsumption, bad weather...
And oh watch out for rapid network variations (especially if your elevators runs on the generator without a soft starter or VFD), your inverter could keep disconnecting
21/n

Personally I have been using Victron MP2 for a couple of months now. It's one of the best in the world and still it required some programming and additional components to adapt it to my needs/operation mode.
Hope I didn't miss much 😁 n/n

Bonus: look for programmable inputs/outputs on ur inverter, and what you can do with them. They can be very useful

Bonus 2: you should use the C10/12 battery rating, and not C20 or other.
Also, check for the inverter surge power capacity and duration, coz you will need it