Optimization solution is sub-optimal

[ghost]

Dear community:

I developed the PyPSA-electricity of China following PyPSA-Eur, and when I solve the network, I always got the sub-optimal results, please help me, greatly thanks. Here attached the solving messages: Optimize a model with 5049261 rows, 2167023 columns and 11000291 nonzeros
Model fingerprint: 0xd7996ca1
Coefficient statistics:
Matrix range [1e-02, inf]
Objective range [3e-02, 3e+05]
Bounds range [2e+01, 1e+11]
RHS range [6e-01, 9e+09]
Warning: Model contains large matrix coefficient range
Warning: Model contains large rhs
Warning: Model contains large bounds
Consider reformulating model or setting NumericFocus parameter
to avoid numerical issues.
Presolve removed 2508820 rows and 303697 columns
Presolve time: 3.91s
Presolved: 2540441 rows, 1863326 columns, 8129375 nonzeros
Elapsed ordering time = 7s
Elapsed ordering time = 10s
Elapsed ordering time = 15s
Elapsed ordering time = 20s
Elapsed ordering time = 25s
Ordering time: 27.08s

Barrier statistics:
Dense cols : 351
AA' NZ : 1.107e+07
Factor NZ : 8.437e+07 (roughly 2.5 GB of memory)
Factor Ops : 3.805e+10 (less than 1 second per iteration)
Threads : 8

              Objective                Residual

Iter Primal Dual Primal Dual Compl Time
0 3.39594393e+18 -nan(ind) 7.64e+14 0.00e+00 -nan(ind) 42s

Barrier performed 0 iterations in 42.12 seconds (11.03 work units)
Sub-optimal termination - objective 3.39594393e+18

WARNING:linopy.constants:Optimization solution is sub-optimal:
Status: ok
Termination condition: suboptimal
Solution: 2167023 primals, 5049261 duals
Objective: 3.40e+18
Solver model: available
Solver message: 13

INFO:pypsa.optimization.optimize:The shadow-prices of the constraints Generator-fix-p-lower, Generator-fix-p-upper, Generator-ext-p-lower, Generator-ext-p-upper, Line-ext-s-lower, Line-ext-s-upper, Link-ext-p-lower, Link-ext-p-upper, Store-ext-e-lower, Store-ext-e-upper, StorageUnit-fix-p_dispatch-lower, StorageUnit-fix-p_dispatch-upper, StorageUnit-fix-p_store-lower, StorageUnit-fix-p_store-upper, StorageUnit-fix-state_of_charge-lower, StorageUnit-fix-state_of_charge-upper, Kirchhoff-Voltage-Law, StorageUnit-energy_balance, Store-energy_balance, Line-loss_upper, Line-loss_tangents-1--1, Line-loss_tangents-1-1, Line-loss_tangents-2--1, Line-loss_tangents-2-1 were not assigned to the network.
INFO:main:Maximum memory usage: (10597.19921875, 1749001689.9610138)
INFO:pypsa.io:Exported network 'base_s_31_elec_Co2L-3H.nc' contains: global_constraints, links, stores, buses, generators, carriers, lines, loads, storage_units

[fneum]

Do you know about PyPSA-China https://github.com/pik-piam/PyPSA-China-PIK?

[ghost]

Yes, I know this model. But I want to learn some modeling knowledges and do some specific research. So I need to develop a model alone. Everything is done, but met this solving error.