a transistor turned all the way on, which is what we do with pwm and/or mppt can be considered a concoction of resistors and diode drops. The voltage coming out the business end of it will be lower than the voltage going in. So, you are welcome to word that by saying that they dissipate power. It makes little difference to me. High current, hot mosfets turned all the way on will tend to have a d-s drop of 1-2 volts. Of course, you can add more transistors in parallel to partially counteract this problem at a cost. That's what the datasheets say, and it isn't a lot different for bipolars. Well, losing voltage can push you away from maximum power point and cost you additional optimizational losses, so, for a a 30 volt panel for example can comfortably charge a 24 volt battery quite optimally. If, however, we subtract 1.5 volts from the 30 because of transistor losses, 28.5 volts remain. This will still comfortably charge a 24 volt battery, but if we then account for IR drops, we may be cut down to 27.5 or 27 volts. To charge a 24 volt battery up to its top at the 20 hour rate requires very close to 28.2 volts, so the 27.5 is 0.7 volts shy. The panel has to make up for that by reducing its current flow in order to push the voltage up higher. So, we lose both voltage and current. We can choose the panels that output a couple of extra volts. Of course, that can be done, again at a cost. So a system of multiple relays does not have much of any d-s drop, but they don't pwm very well. So the obvious solution to that problem is to have charging module options that use multiple pv arrays, turning them on separately so as to provide differing current flows for different charge stages. This is a good idea anyways for relay systems as relays tend to have current limits of around 60-120 amps. So, even in a 48 volt system, we are talking about 3-5 percent power loss, which for a 5 kw system amounts to around 200 watts, which can cost $300 or so to replace.
OK, so in truth, the relay strategy is not optimal for all designs. It sucks for long distance cable runs because you have to provide battery voltage at battery current wheras mppt systems can raise the voltage and have smaller IR loss. So other strategies need to be cared for in a flexible system. Also, if you know a good way to cut the voltage drop across transistors down to 0.2 volts or something, then of course, I would be very interested. So, yes, for 12 volt systems, mppt or pwm could easily (not necessarily) cost 10-15 percent of the power up front. For 48 volt systems, this is of course less of a concern. I am shooting for 48 volt (dual 24 volt poles) but a flexible system will allow for people to choose their favorite charging system.
Hmmm. regarding the question mark of being ee/cs. I guess I have been in enough degree contests to prefer to avoid that route because what we need more than to compete is to get along somehow. But let's just say that I'm pretty sure one of the driving forces behind arduino is open source strategy. So, when DIYers show up. This is of course beautiful. It will be more beautiful if we can work as a group to accomplish a public project. There should be plenty of people around to work on that. I can get our guys together and try to hit up kickstarter for public funding for a public project, but I'm reticent for a few reasons (that may melt away). So, one way or another, it is our intention to accomplish some strategic technological additions to the open source community that are designed to help re-balance the social flow. If you prefer for society to never evolve or improve, I suppose that is your right.
So, I'm going to tell you this because I guess I have to, but the reason why all the other stuff got into the talk is because I am a systems theorist who has spent some decades examining the current social structure. There is a pathway to overcoming some of its current weaknesses that lies down the lines of the concept of balance. Everything is connected to everything in the real world, and small deeds can have large results. ... or they can peter out and be forgotten in the infinity of time. (butterfly effect) So, I didn't want to get too deep into that kind of stuff because this isn't that kind of forum. Nevertheless, systems and complexity theory have a great deal to say about what we aught to be focusing on. So I have hoped for people to see the potential advantage of providing a top class solution to the dc power distribution problem .. open source. Of course, if people don't care about that, then I hope that they care about something else in relationship to the development of a top class mppt/charge controller architecture.
Let's see ... 1938, Otto Hahn discovers two kinds of fission, thorium Thorium fuel cycle - Wikipedia and uranium. Thorium is far far safer to fission than uranium, but you can't make bombs with it. So, I am going to try to respect the topic of the forum and not drag you any deeper into that. There is enough info. in the wiki page for anyone who is curious, except that I don't think it mentions chinas development of thorium fission reactors. OK, so what it boils down to is that I have a big picture in my head. I realize that some people don't like big pictures. I'm not accusing you of that. Feel free to make your own choice.
The arcs in relays as they open/close are of course definitely on topic. Arcs destroy relay contacts and can render charge control dysfunctional, potentially even dangerous. So if we want to use the relay option for cases where it is optimal, then we have to study this issue out.
I don't know just what sort of people are here. As my nameplate says, I am a noob on this site. I must decline to further discuss egrouphub in detail on this site because it is not on topic, and I wish to respect arduino.cc as I wouldn't be thrilled if people got too far off of topic on our site either.
Thank you for your comments. I hope others feel more positive about it. 
So, in case anyone is noticing, I have been on this project for some several months already. I have examined the curves, data of parts, etc. found a lot of ideal electronic parts and created some strategies, but I don't expect to out-think the arduino community by myself as that would of course be ridiculous.
And class d amplifiers just save 1/2 to 3/4 of the power that is spent by other amplifier classes. This is a big deal if you are paying for all of your power up front. They can be powered directly by dc power sources, saving us the expense of the power supply and the energy it wastes humming at 60 hz all day, and the space it takes up and the shipping weight. So it's just another way of reducing system cost, but It is also not directly on topic. I just pointed out that if we can reduce the cost of multiple parts of a power system, we can cut the entire system cost by as much as approx. 50%, which is huge. The price of solar power dropping is huge. It's huge again if we can use it more efficiently (i.e. use less of it). And there are a lot of ways to do that that are improvements over what solar installers are currently setting up. (yes, I have discussed with solar installers and have a good idea as to what they are currently doing.) I'm not asking anyone to get involved in that kind of stuff right now, just trying to paint the picture a little wider in an attempt to help people to feel more motivated. Looks like it backfired and got smoke all over my face. I'm reminding myself of Ronald Weasly and his wand. LOL.
OK, it has been a pleasure.
mgshightech