tile.java

package loordgek.teslatest;

import net.darkhax.tesla.capability.TeslaCapabilities;
import net.minecraft.tileentity.TileEntity;
import net.minecraft.util.EnumFacing;
import net.minecraftforge.common.capabilities.Capability;
import net.minecraftforge.energy.CapabilityEnergy;
import net.minecraftforge.energy.EnergyStorage;

import javax.annotation.Nullable;

public class tile extends TileEntity {
    EnergyStorage energyStorage = new EnergyStorage(20000);
    Wrapper wrapper = new Wrapper(energyStorage);


    @Override
    public boolean hasCapability(Capability<?> capability, @Nullable EnumFacing facing) {
        return capability == CapabilityEnergy.ENERGY ||
                capability == TeslaCapabilities.CAPABILITY_CONSUMER ||
                capability == TeslaCapabilities.CAPABILITY_HOLDER ||
                capability == TeslaCapabilities.CAPABILITY_PRODUCER ||
                super.hasCapability(capability, facing);
    }

    @Nullable
    @Override
    public <T> T getCapability(Capability<T> capability, @Nullable EnumFacing facing) {
        if (capability == CapabilityEnergy.ENERGY) 
            return CapabilityEnergy.ENERGY.cast(energyStorage);
        
        if (capability == TeslaCapabilities.CAPABILITY_CONSUMER)
            return TeslaCapabilities.CAPABILITY_CONSUMER.cast(wrapper);
        
        if (capability == TeslaCapabilities.CAPABILITY_HOLDER) 
            return TeslaCapabilities.CAPABILITY_HOLDER.cast(wrapper);
        
        if (capability == TeslaCapabilities.CAPABILITY_PRODUCER)
            return TeslaCapabilities.CAPABILITY_PRODUCER.cast(wrapper);
        
        return super.getCapability(capability, facing);
    }
}

Wrapper.java

package loordgek.teslatest;

import net.darkhax.tesla.api.ITeslaConsumer;
import net.darkhax.tesla.api.ITeslaHolder;
import net.darkhax.tesla.api.ITeslaProducer;
import net.minecraftforge.energy.IEnergyStorage;

public class Wrapper implements ITeslaConsumer, ITeslaHolder, ITeslaProducer {
    private final IEnergyStorage energyStorage;

    public Wrapper(IEnergyStorage energyStorage) {
        this.energyStorage = energyStorage;
    }

    /**
     * Offers power to the Tesla Consumer.
     *
     * @param power     The amount of power to offer.
     * @param simulated Whether or not this is being called as part of a simulation.
     *                  Simulations are used to get information without affecting the Tesla Producer.
     * @return The amount of power that the consumer accepts.
     */
    @Override
    public long givePower(long power, boolean simulated) {
        return energyStorage.receiveEnergy((int) power, simulated);
    }

    /**
     * Gets the amount of Tesla power stored being stored.
     *
     * @return The amount of Tesla power being stored.
     */
    @Override
    public long getStoredPower() {
        return energyStorage.getEnergyStored();
    }

    /**
     * Gets the maximum amount of Tesla power that can be held.
     *
     * @return The maximum amount of Tesla power that can be held.
     */
    @Override
    public long getCapacity() {
        return energyStorage.getMaxEnergyStored();
    }

    /**
     * Requests an amount of power from the Tesla Producer.
     *
     * @param power     The amount of power to request.
     * @param simulated Whether or not this is being called as part of a simulation.
     *                  Simulations are used to get information without affecting the Tesla Producer.
     * @return The amount of power that the Tesla Producer will give.
     */
    @Override
    public long takePower(long power, boolean simulated) {
        return energyStorage.extractEnergy((int) power, simulated);
    }
}