PV Gap

Kelly Said:

what solar panels do i need to power my 9.6v r/c car. i am tired i recharging my batteries.?

We Answered:

A panel big enough to power the car direct would be too big for the car to carry. Use the panel to charge spare batteries.

Glenda Said:

Instead of building huge solar energy plants in the desert...?

We Answered:

Not really. At least, not until photovoltaic prices plummet some more!


You save a bit of money by not having to transport the power that far, but if you're in a building you either have to use the energy straight away, or store it in batteries (expensive), or put it back into the grid (so you're still getting grid inefficiencies).



The cheapest forms of solar power are concentrating solar power (CSP) and thin film photovoltaics. CSP can't really be done on rooftops*, and the two cheapest thin film technologies are not available for residential use yet (FirstSolar sell CdTe panels, but only on a commercial basis. Solyndra and NanoSolar are working on CIGS, but not many panels for sale yet). So residential panels tend to be silicon.

Larger plants also get economies of scale: you can build modules close together and save on wiring, make the most efficient use of inverters etc, which all save money.

In the UK it costs somewhere between £4,000-6,000 per kWp of residential solar power if you buy a 4kW system. Waldpolenz solar park in Germany used thin film cells and economies of scale to cost less than £3,000/kWp and this was before solar cell prices fell last year.

Finally, deserts are just much, much sunnier. In the Mojave desert, you can expect to generate about 2,200kWh per year per kW of installed solar power. On a Manchester rooftop you can expect about 750-900kWh.


So in summary: economies of scale and better tech means that larger solar parks sometimes work out at as little as half the price per unit of power compared to rooftops. And being in a desert more than halves the price again, relative to being on a rooftop in the UK. A 75%+ cost saving can justify extra transmission costs!




Ofc, in some areas it's economic to put solar cells on rooftops, and it'll become more useful as time goes on and prices fall. And there are the advantages of using power close to where it's generated and not taking up any extra land. So we will see solar power on rooftops becoming more and more important, but desert solar has big advantages.