Re: solar panels deployed on the earth would generate 4x the amount of power
The point with SBSP is that efficiency doesn't really matter. There's near-permanent insolation in high orbit, and if we need more power we just have to bung up some more satellites and build some more rectennas down on Earth. The transmission frequencies aren't blocked by clouds or atmospheric water vapour, and power generation is constant, day and night.
Efficiency always matters. So a crude view would be you're taking 1360W/m^2 at TOA and converting it into 100W/m^2 at the surface. This isn't efficient, but as the input is 'free', who cares, right? Bigger issue is the cost of providing some useful amount of electricity at a commercial price. Wiki has an article here-
https://en.wikipedia.org/wiki/Space-based_solar_power#Launch_costs
To give an idea of the scale of the problem, assuming a solar panel mass of 20 kg per kilowatt (without considering the mass of the supporting structure, antenna, or any significant mass reduction of any focusing mirrors) a 4 GW power station would weigh about 80,000 metric tons
But that cost may fall as launch costs (ie Starship) or lighter transmitter arrays are developed. But-
For comparison, the direct cost of a new coal[75] or nuclear power plant ranges from $3 billion to $6 billion per GW (not including the full cost to the environment from CO2 emissions or storage of spent nuclear fuel, respectively)
And those costs are (or could also be) falling. There's a lot of creative marketing around 'levelised' costs to favour pet technologies to make 'renewables' look economically attractive. But without subsidies, nobody would buy the product, if alternatives could generate electricty 'cleanly', reliably and predictably at a far lower cost per MWh. Then there's the cost of the terrestrial infrastructure, ie land, rectenna and safety costs. Because the power levels are way above safe levels, the reciever arrays would have to be remote, which means adding the transmission costs for grid tie-ins as well. Obviously if an SBS system can deliver only tens or hundreds of MW, the costs need to be spread over those MW, and the MWh sell price is likely to be even more expensive than offshore wind.
Then there's land use efficiency. The US has a lot of unused Federal land that could be converted into power reserves, but the UK does not. But then how much energy per km^2 could be generated? Nuclear is very energy efficient in land use terms, ie a 500MW SMR can comfortably occupy a small part of a submarine, or building.
Rectennas that can be hung above farmland, woodland, wetland etc. Because the area the cover is almost entirely open to the sky, and you can continue growing stuff underneath. Levels of microwave power will never be high enough to cause problems.
Those are big assumptions. But 'renewables' proponents seem to be very much anti-wildlife. So farmers already know that one way to keep birds off crops is to make a 'rectenna' above them. Birds and bats will fly into the wires and may get killed or injured. This may be a problem if the animals are pollinators or insectivores. Plus there's the potential effects on insects, or the plants themselves, or even wetlands because the microwave energy will be absorbed. But the current safety measures seem to be making it remote, so power levels are currently unsafe to farm in, or have a woodland picnic under the slowly browning and dieing forest.