Could someone explain to me a little more about how the metal and energy system works? I see green and red numbers on both meters and no matter what it always allows me to build whatever I want. So how do these two resources work?
(Disclaimer: figures used are from the wiki, which may be outdated, but the gist is all correct even if the exact numbers are off.) All construction costs in PA are in metal. Each fabricator spends energy when building things, at a cost of "X energy per 1 metal" where X varies by the type of fabricator. So a bot factory costs 600 metal to build. Your commander can output 30 metal per second at 50 energy per metal, so he spends 1500 energy/second to build the bot factory over the course of 20 seconds. A fabrication bot can output 10 metal per second at 100 energy per metal, so he would spends 1000 energy/second to build the bot factory over the course of 60 seconds -- he doesn't tax your economy as much per second but ultimately he spends more total energy than your commander and he takes a lot longer. A fabrication aircraft can output 6 metal per second at 200 energy per metal, so spends 1200 energy/second to build the bot factory over the course of 100 seconds. So the bot factory costs 600 metal ...and the energy cost varies based on who is building it. Some things (namely radar) consume energy while running but all construction costs are in pure metal; the energy cost is incidental and dependent on the unit doing the work. Construction rates slow down if you do not have enough metal or energy on hand to run at full speed. In this event, your construction rate will be whichever ratio is worse: metal income divided by metal used OR energy income divided by energy used. For example, you have 200 metal income / 210 metal used and 1,000 energy income / 10,000 energy used. The worst of the two ratios is energy: 1,000/10,000 or 10%. Your build rate is 10% normal because of the lack of energy. Usually the quickest way to screw your economy is by building too many fabrication units and having them all try to work at the same time. Advanced fabrication bots consume 3000 energy per second so building too many of them too quickly can actually slow your economic growth -- that new energy generator you were trying to build is being slowed down by these advanced fabrication bots that are trying to build your nuke. Better to let the energy generator build quickly and add new bots to the nuke as your income goes up. As of the last patch, energy consumption in the red is extra bad because it can also shut off your radar, so best to keep energy in the green all the time and let metal be the limiting factor, running slightly in the red all the time. (If both are green then you are probably wasting resources and need to build more stuff!) Side note: Factories are more efficient than fabrication units when it comes to energy consumption. It's far more energy efficient to have multiple factories than it is to have 1 factory being assisted (unless the assisting unit is your commander, which is the only unit that's more efficient than a factory). Side note #2: "Storage" lets you go in the red and still run full speed for as long as storage holds out. So if your energy deficit is -500, it will take 500 per second out of storage and let units build full speed (as if your income/use ratio was 100%) until storage is empty. Some extra storage can help even out the "boom and bust" nature of the economy.
As far as storage is concerned, you want to build your first energy storage very early (after getting about 10 or so power gens). How many more you need beyond that depends on how good you are at balancing your energy income. If it is fluctuating a lot and quickly draining/filling as factories turn on/off and fabbers move around, you probably need more energy storage. Metal storage is a completely different story. Every bit of metal stored is a potential unit that could be in play. For example, having ~90k metal stored is equivalent to the cost of a nuke. This means you shouldn't be stockpiling metal at all because it is preferable to have the metal existing as a unit providing more income or damage potential than it is just existing as a number. That being said if you consistently find yourself at full metal with positive income, you might consider building some, but this is really only a short term crutch. In the longer term, you should be examining your playstyle and finding ways to avoid wasting metal. Advanced players generally avoid metal storage like the plague.