Sorry for the littering - post moved to a separate thread (cannot be canceled).
Hello everyone,
I am in front of the purchase of a photovoltaic installation. Roof slopes 41 degrees on 4 sides. Little space to the south via DHW solar panels and a swallow. Generally, the panels are planned to the east and west (with a slight curvature to the south). I am planning a hybrid installation with the UPS function (off-grid operation possible) with a later purchase of a battery.
From the many offers I received, I chose the 2 most comprehensively presented configurations:
COMPANY A (large - with twelve branches in major cities and "thousands of installations", it is said that it is to enter the stock exchange soon):
- 2 strings x 8 panels, power max. 6.56kW. Type SUNPRO POWER 410W SP410-108M (Uoc = 31.25V, Umpp = 37.33, but the calculated minimum voltage for 70 degrees C is 27.59V / panel which gives 220.72V for a string of 8 panels), warranty 30 years for efficiency> 83.5%
- HUAWEI SUN2000-6KTL-M0 or SOFAR HYD 6KTL-3PH inverter.
My analysis of the above-mentioned parameters and calculations shows that:
1. for both inverters the maximum current in strings is exceeded (the panels have a maximum of 13.41A, and the inverters have a maximum of 11A (SUN) and 12A (SOFAR)
2. for both offered inverters, the string voltage at the MPPT inputs of the inverter is too low to achieve the maximum power (220.72V) and 285V (SUN) or 320V is needed! (SOFAR)
3. The inverters are significantly scaled in terms of the power provided by the panels (practically the strings will work interchangeably), which I suppose will give the max power. from panels in the range of 3.3kW to 4.5kW.
COMPANY B (smaller, private, headquartered in one of the largest cities in eastern Poland):
- 2 strings x 6 panels - power max. 5.4kW. ML type ML-S6MF / T1-450-144 system - 450W (Uoc = 49.8V, Umpp = 41.00, the calculated minimum voltage for 70 degrees C is 43.97V / panel which gives 263.82V for a string of 6 panels), 25-year warranty for efficiency> 83%, product warranty: 12 years?!
- HUAWEI SUN2000-5KTL-M1 inverter.
My analysis of the above-mentioned parameters and calculations shows that:
1. for the inverter, the maximum current in strings is slightly exceeded (the panels have a maximum of 11.82A, and the inverter is max. 11A),
2. The inverter is significantly scaled in terms of the power supplied by the panels, analogous to the above case.
3. It amazes me to give a guarantee for efficiency twice as long as for the entire product? !!! (assuming that the "producer" does not collapse in the next year).
The above-mentioned proposals are the least shocking tip of the iceberg among other received offers, the substantive value of which is not even worth mentioning here.
Unfortunately, I have an electrical education with qualifications and I can still read and understand offers in related fields. But is no one in this country able to give a solid offer for fair (large) money (rhetorical question)?
Could I ask my colleagues for suggestions on the above-mentioned offers? In particular, as for the quality of the proposed components and what solution based on the above-mentioned information, my colleagues would recommend me for a price of around 25,000-30,000.
I would like to do it myself, but I do not have such a possibility, so I would use a solid offer from a trusted professional
from the vicinity of Krakow.
regards
and thank you for any suggestions
Andrew
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, usually MPPT inputs are connected when there are two strings connected in parallel, then the current sums up and exceeds the allowable input current of the inverter.
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