20-06-2022, 06:13 PM
2 cents FWIW de ZL1RS ...
We have 5.2kW of panels (16 x 330W), 2 x 60A MPPT chargers, a 48V 9.6kWhr battery bank, a 7.5kW low frequency DC>AC inverter module with 4kW of toroids. This powers my shack and 95% of our modest household electricity consumption. We still have a mains power grid connection that we switch over to during bad weather (the solar panel charge output drops dramatically under cloudy conditions). To gain more autonomy we'd need a larger battery bank or run a generator during bad weather, neither of which stacks up financially in NZ.
Note that our system is a DIY hobby activity for me ... in NZ (no subsidies) it is not cost effective to have it done professionally if there is a mains power grid connection available. In ZL the capital and on-going cost of a professionally installed off-grid solar system over its lifetime (especially with battery replacement) is not so different to the cost of buying electricity from the grid.
The following is 'learn from mistakes' advice! If it weren't for the convenience factor of having the system close by for monitoring I'd consider relocating/rebuilding our solar plant due to the points below ...
1) Locate the solar system and panels away from any direction you are likely to beam, and get it as far away as practical from your antennas.
2) Optimise solar panel angles for winter sun, the longer days of more plentiful summer sun will take care of itself.
3) Solar panel wiring can radiate RFI/noise from MPPT solar controllers (chargers), so consider ground mounting the panels rather than roof mounting (think of solar panel wiring as antennas!) Use metal conduit for shielding the cables.
4) Seek advice on low RFI chargers (aka solar controllers). e.g. we are using EPEVER iTracer 60A MPPT units here - one per 2.6kW of panels with the two outputs in parallel across the battery bank. These were purchased 6 or 7 years ago, so not sure if the current model is still as good (re: RFI). Ours generate a little noise and that is effectively radiated via the unshielded solar panel wiring running up to the roof mounted panels :-( However, $300 worth of clip-on ferrites reduced the noise by several dB ... and there is no noise left when using Yagis with clean radiation patterns that are not beaming directly at the solar array. I get more noise from power lines and dairy shed electronics that are 2 - 3 km away than from our own solar system (unless beaming at it).
5) Also seek advice for the DC-AC inverter. Initially I had a high frequency 'pure sine wave' EPEVER unit which was crazy noisy. When I reconfigured our solar system from 24V to 48V I built a low frequency inverter based on a PCB module from China and 4 x 1kVA toroids (kept the original 230V winding, and rewound the low voltage side to suit the PCB module). The noise from the low frequency unit was a small fraction of that from the high frequency 'pure sine wave' unit.
There is still some noise from the system which gets worse at lower frequencies. Frequencies down to 7 MHz are OK if the HF antennas are located about 60 meters away and have effective common mode chokes in the coax feed line.
If our solar system were for radio equipment only, I'd do things differently and keep everything at DC with 'old school' linear regulators for charging and use two systems ... a 12V system for the radios and a 48V system for the LDMOS amplifiers.
Cheers, Bob ZL1RS
We have 5.2kW of panels (16 x 330W), 2 x 60A MPPT chargers, a 48V 9.6kWhr battery bank, a 7.5kW low frequency DC>AC inverter module with 4kW of toroids. This powers my shack and 95% of our modest household electricity consumption. We still have a mains power grid connection that we switch over to during bad weather (the solar panel charge output drops dramatically under cloudy conditions). To gain more autonomy we'd need a larger battery bank or run a generator during bad weather, neither of which stacks up financially in NZ.
Note that our system is a DIY hobby activity for me ... in NZ (no subsidies) it is not cost effective to have it done professionally if there is a mains power grid connection available. In ZL the capital and on-going cost of a professionally installed off-grid solar system over its lifetime (especially with battery replacement) is not so different to the cost of buying electricity from the grid.
The following is 'learn from mistakes' advice! If it weren't for the convenience factor of having the system close by for monitoring I'd consider relocating/rebuilding our solar plant due to the points below ...
1) Locate the solar system and panels away from any direction you are likely to beam, and get it as far away as practical from your antennas.
2) Optimise solar panel angles for winter sun, the longer days of more plentiful summer sun will take care of itself.
3) Solar panel wiring can radiate RFI/noise from MPPT solar controllers (chargers), so consider ground mounting the panels rather than roof mounting (think of solar panel wiring as antennas!) Use metal conduit for shielding the cables.
4) Seek advice on low RFI chargers (aka solar controllers). e.g. we are using EPEVER iTracer 60A MPPT units here - one per 2.6kW of panels with the two outputs in parallel across the battery bank. These were purchased 6 or 7 years ago, so not sure if the current model is still as good (re: RFI). Ours generate a little noise and that is effectively radiated via the unshielded solar panel wiring running up to the roof mounted panels :-( However, $300 worth of clip-on ferrites reduced the noise by several dB ... and there is no noise left when using Yagis with clean radiation patterns that are not beaming directly at the solar array. I get more noise from power lines and dairy shed electronics that are 2 - 3 km away than from our own solar system (unless beaming at it).
5) Also seek advice for the DC-AC inverter. Initially I had a high frequency 'pure sine wave' EPEVER unit which was crazy noisy. When I reconfigured our solar system from 24V to 48V I built a low frequency inverter based on a PCB module from China and 4 x 1kVA toroids (kept the original 230V winding, and rewound the low voltage side to suit the PCB module). The noise from the low frequency unit was a small fraction of that from the high frequency 'pure sine wave' unit.
There is still some noise from the system which gets worse at lower frequencies. Frequencies down to 7 MHz are OK if the HF antennas are located about 60 meters away and have effective common mode chokes in the coax feed line.
If our solar system were for radio equipment only, I'd do things differently and keep everything at DC with 'old school' linear regulators for charging and use two systems ... a 12V system for the radios and a 48V system for the LDMOS amplifiers.
Cheers, Bob ZL1RS